Chudley, R. and Greeno, R. (2006) Building Construction Handbook, 6th edn. Oxford: Butterworth-Heinemann


Books can be ordered from most bookshops or online from Amazon.

Before starting you should read the ‘Study Guide’ accessible from the link on the left.

12.1.1 Purpose & Requirements of Buildings
12.1.2 Structural Concepts
12.1.3 Components and Parts
12.1.4 Drawings
12.1.5 Site Investigation
12.1.6 Ground Stabilisation
 
 

12.1.1 Purpose & Requirements of Buildings

The purpose of a building is to meet certain criteria, this may be to provide a place of shelter, storage, work or leisure (to mention just a few) and in order to do this the building will need to exhibit certain physical characteristics. 

The physical characteristics will depend on the activities which are to be carried out and their relationship and location in respect to other buildings or activities.  Regardless of the use of the building it will need to perform to certain criteria that relate to the structural and environmental considerations. These requirements will be determined by legislation and the purpose and activities undertaken in the building.  In order to determine what these requirements are we need to consider the following factors:

Activities – this looks at what activities are to be carried out in the building as the design, layout and construction of a domestic building will be different from a hotel or a prison, although each is there to provide shelter and accommodation. Likewise for a factory we need to consider the amount of space needed as the size and spans of the building will depend on the type and methods of production which is dependent on the items being produced.

Form – this will be dependent on the type of building and its’ location, an office complex in a city centre is likely to be high-rise where if situation in a rural area it could be low-rise. 

Location – this will not only dictate the form but also the materials used a planning authority is unlikely to allow the construction of a building using materials that was not in keeping with the surrounding area.

Physical Requirements - the physical requirements of the building will need to consider the following:

All habitable buildings will consist of an envelope to provide protection to the inhabitants and their contents. In order to do this it needs to retain its structural integrity under all loads or forces that it is likely to be subjected to.

The form that the structure will take depends on a number of factors such as purpose and location as traditionally buildings have been constructed using locally sourced materials i.e. houses in Scandinavia were made of wood while those in Egypt would be constructed of mud bricks.

The way it is constructed is therefore dependant on type of materials and the structural concept that is used.
 
 

Task 12.1.1 Materials & Technology

Explain how the use of the building will determine the materials and technology that will be used in its construction.

 

 

 
12.1.2 Structural Concepts

These fall into:

Solid Structures where the walls act both to enclose and support. This means that the walls will have to be of sufficient thickness in order to accept the loads applied and transfer them to the foundations. The type of houses that we are probably most familiar with falls into this category and is illustrated below.
 

 
Skeletal (Framed) Structures consists of a framework which supports all loads and resists any imposed loads and transmits these to the foundations. This type of structure consists of a system of beams and columns which create a framework.

 

The frame itself does not provide the enclosing of the building so an additional system is needed, thus panels can be placed over this framework or between the external structural members in order to enclose it. Most people will be familiar with the framed building as illustrated below (This system will be looked at in Section 2 of this unit) though timber frame buildings also fall into this category.

 

 

 

Surface Structures are either made of thin structure of solid material which are curved to provide stiffness, such as reinforced concrete shell where it acts as both the supporting and enclosing element; or a thin flexible membrane structure stretched across supporting members. We will not be looking at these in this unit.

 

 

Task 12.1.2 Framed Construction

Explain the advantages of using a framed construction over that of a solid structure.

 

 
 
 

12.1.3 Components and Parts

The Structure, materials and components which make up a building can be classified as:

Primary elements - these make up the structure of a building and include:

 

Secondary elements - these are added to the building and do not provide structural support they are added to:

Examples of secondary elements are:

Building services are installed as first fix prior to some of the secondary elements and finishing works and also as second fix; they include: 

Finishing’s and fittings include:

 

These elements will be looked at in detail in the other sections of this unit or in Unit 11 Managing Building Services, though you should understand the basic concept and how they relate to each other. An introduction to components can be obtained from Chudley & Greeno Building Construction Handbook.

 

Task 12.1.3 Implications of using Defective Materials

Evaluate the implications of the use of defective materials in modern structures and in the repair and maintenance of traditional structures and buildings of historic interest.

 

 
 

12.1.4 Drawings
 
In order for the designers of a building to convey their requirements; a set of drawings are produced which enables the building to be constructed according to the designers original intentions.
 
Drawings are produced as a two-dimensional image depicting what the building, components or layout position will be.  Drawings can be put into the following categories:
 
Location Drawings This shows where the building will be and what it will look like and includes.
 

 
 
Location Drawing
 
 

Site Plan shows the location on the site relevant to roads, boundaries etc.

  

 
Site Plan
 
 

Floor Plans – show the layout of spaces indicating the size and shape of a room and location of the doors and windows etc.

 

Floor Plan
 
 

Elevations – shows a vertical view of the external view of the building.

 
 

 


 
Elevations
 
 
 

Sections  - vertical view of the building showing cross-section.  
 

 

 
Assembly Drawings 
 
These show how the building is constructed or assembled on site and provides details on how it is constructed. It shows the size and shape of the parts ie: how the roof section joins to the wall or the make-up of a window.
 
 

Assembly Drawings
 
 

Component Drawings 
 
These provide detailed information about the component and how it is to be made.
 
 
Scales used
 

Plans are usually drawn to scale, which means that they are drawn at a specific ratio relative to the actual size. The scale used will depend on the type of drawing. For example, site plans are often drawn at 1:100 or 1:200 while a floor plan may be drawn at 1:50. Detailed views could be 1:25.

 
Showing of Materials
 
Materials used are shown by a convention of hatching this is where each material has a different fill, examples being:
 

 

 
The way a window or door is hung and opens can also be shown as illustrated below. 
 

 

Side Hung window on left side
  
 

The main hatchings and symbols depicting an item on the drawing can be found in Building Construction by Chudley and Greeno and in Construction Site Studies by Foster though you should also consult British Standards which list all drawing symbols and abbreviations used.

 
 

Task 12.1.4 Drawings

List and briefly explain the drawings you would expect to be given before you commence a job and those which you will receive during the construction process.

 

 
 
 
12.1.5 Site Investigation

It is essential that before any building is designed a thorough understanding of the site and soil conditions onto which the building is to be placed are understood as this fundamentally affects the design of the building.

Sub-soil, sub-structure and superstructure must act together to maintain the stability of the building and cannot be taken in isolation. It is also essential for all parties to be aware of any challenges relating to sub-soil conditions before any work is planned as this will also have an effect on the likely costs involved.

Before reading through this sub-section you should play the video ‘Site & Soil Investigation’ to obtain an overview, you can then return and read the text ensuring that you understand all of the factors  and how they relate to the process of ensuring that the designer knows what the site and soil conditions are.

 

Objectives of Site Investigation

According to BS 5930, a site investigation is carried out to:

 

Preliminary Site Investigation

When the nature of the site is unknown the engineer usually makes a preliminary investigation of relevant information which is obtainable from such sources as:
 

1)  Mining authorities ‑ existing and future factors effecting ground movement.

2)  Ordinance Survey ‑ land contours, rights of way, rivers, existing buildings. (Look at old maps ‑ pond in wrong place)

3)  Geological Central Record.

4)  Met Office ‑ frost hollows, prevailing winds and severity, rain fall.

5)  Water Authorities ‑ water tables, flood plains.

6)  Planning and Building Control. (tree preservation orders)

7)  Utilities ‑ gas, water, electricity, British Telecom, sewage.

8)  Listed and historical buildings.

Visual observations can give some information, i.e. the type and extent of vegetation (Willow trees like water, as do marsh plants) If no plants it could be an old tip. Talk to the locals. Names can give you a clue to what was there before, i.e. Water Lane.

Shrinkable clays give their own evidence in dry weather.

Look at buildings nearby to see if they show any signs of subsidence.

Local railway cuttings, quarries and excavations may give some information of the subsoil strata.

Note should also be made of access to the site for plant and materials considering roads, bridges and overhead cables.

 

Soil Mechanics

This provides the engineer with information on the properties of the soil which geology alone cannot provide. The information is obtained by the thorough examination of the site and the examination of soil samples in a laboratory.

 

Site Exploration

The aim is to provide a survey of the subsoil in order to find out the nature and disposition of the soil below ground level, and to obtain samples of the soil for testing in the laboratory

The exploration should be done at the same time as the preliminary design of the building; this prevents obtaining insufficient or unwanted data.

The extent of the exploration will depend on the size and type of structure, the nature of the site, and the availability of local geological information.

The exploration should be taken deep enough to include all strata likely to be significantly affected by the loading of the building. This depth will depend on the weight, size and shape of the loaded areas.

 

Methods of Sub Surface Investigations

Trial Pits

Traditionally used for site investigations up to about 3m deep, the deeper they are the more costly they are to carry out, in unstable ground close timbering or sheet piling may be necessary In most cases the sub soil can be investigated at the side of the pit in an undisturbed state, and samples can be easily removed for testing purposes. This method may also be used in the location of underground pipes and cables etc.

 

Plate Bearing Test

This can be carried out on the surface or in a trial pit: It simply consists of loading a steel plate of known area and recording the settlement over a period of time, bricks, concrete blocks or water may be used as a temporary weight.
 

Borings

Hand Boring – These may be used in reasonably soft soil in depths up to 6 to 9m. Unlined boreholes are cut with a post‑hole auger and extension rods. The auger is usually 100 ‑ 150mm in diameter and is turned by a tee‑piece handle.  Other types of auger allow the hole to be cut wider than the drill to allow liners to be inserted to prevent the bore hole falling in.

For depths greater than 9m boring tackle and winch is usually used. The boring is by hand but the raising of the auger and soil is done by winch. The hand rig is suitable for hole up to 200mm in diameter and up to 24m in depth. Anything deeper than this usually requires a power winch.


Mechanical Boring   ‑ this speeds up the process and facilitates easier boring, thus reducing cost when a large number of holes are required.

For penetrating very hard soil or rock various types of rotary drills may be used with hollow core‑bits for the recovery of sample cores. This method is known as Rotary Boring.

In gravel soils steel linings will be required to prevent the collapse of holes. The linings vary in length from 0.6 to 2m. They are screwed together and driven as the boring process continues.

 

Wash Boring – this is used in small grain soil such as sand exist, It consists of pumping water down a steel tube and out the bit. It returns via tubes up the bore hole carrying with it particles of the soil in suspension. This method is not suitable for obtaining a detailed section of the soil.

  

Shell or Percussion   ‑   this consists of a steel shell being dropped into the soil, forcing the soil into a cylinder. The cylinder is then withdrawn and the soil removed.

Two types of cylinder are available: With flap for non‑cohesive soil; and without flap for cohesive soil. Both incorporate a cutting edge. Cylinders are approx. 300mm in diameter and 1.5m long.

To aid the cylinders penetration and reduce friction the bore hole is flushed with water.

 

Headings        

 



These are less costly in undulating ground.

 

Penetration Test

Fairly inexpensive, based on the measurement of resistance to driving some form of probe into the ground.

 

Sounding Test

A development of the penetration test in which a tube with a retractable cone is driven to a predetermined depth: The inner cone is then forced into the strata and the resistance measured.

Vane Test
 

 

This is forced into the ground and twisted until the soil is sheared. The force required to twist the vane is directly related to the shear strength and bearing strength of the soil.

 

SOIL SAMPLES

Disturbed

These are brought to the surface by boring tools. The sub strata will be broken up, or even destroyed.

Care should be taken to ensure that the sample is representative of a certain size. Samples which have been water jetted should be allowed to settle in a trough thus forming a sludge.

Samples are placed in air tight containers of 0.5kg capacity with most of the air removed. The containers are numbered externally and labeled. Stone is placed carefully in crates to prevent damage during transportation.

 

Undisturbed

This tries to maintain the natural properties of the material so that quantative laboratory tests can be made. This is important for compressive and strength tests as strength properties can alter by disturbance.

To obtain soil specimens from bore holes a sampling tool/tube is used. This replaces the auger when each new stratum is reached and extracts an undisturbed core of the subsoil The tube is driven into the ground then rotated to break off the core, it is then removed and the ends capped with either wax or rubber to maintain the moisture content of the sample.

Undisturbed samples should be taken at each change of strata and at every 1.5 to 2m depth.

Where clay is exposed hand samples may be taken using a knife. Otherwise a core sample is taken.

         

Soil Classifications

In order to be able to judge the likely behaviour of any soil under load, it is necessary to be able to identify it so that it may be compared with similar soils, the behaviour of which is already known.

The physical properties of a soil which are most relevant to foundation designs are closely linked with the size and nature of the soil particles and with its moisture content.

 

Classification by Grain Size              (BS 1377:1967)

Clay :                     particles smaller than 0.002mm

Silt :                      particles between 0.002 and 0.06mm

Sand :                    particles between 0.06 and 2mm

Gravel:                  particles between 2 and 60mm

Boulders:               particles above 60mm

The size is established by sieving and sedimentation.

Sieving cannot be used for silts and clays so the particles are mixed with water and separated by sedimentation (the larger particles sink more quickly)

 

Basic Subsoil Classifications 

Rock ‑ a very wide strength range.

Cohesive Soil ‑ clay and silt

Consolidation (and therefore settlement) occurs as water is squeezed from the pore spaces. Shear strength is derived from cohesion between molecular particles; it is a fixed physical property independent of load. When loaded cohesive soils have a greater initial settlement and compressibility than non‑cohesive soils.

Non‑cohesive Soil ‑ sand and gravel

Shear strength is derived from friction between the sand or gravel particles ‑ this increases as pressure increases.  There is, therefore, less risk of shear failure.

Any settlement taking place will happen over a long period of time.

As there are more voids in non‑cohesive soils they are more permeable resulting in less volumetric change.

Made up Ground ‑ unsuitable until consolidated.

Peat ‑ unsuitable because it is organic and will therefore decompose.

 
 

Task 12.1.5 Site Investigation

Outline the things that a site investigation is looking to determine.

 

 
 


Laboratory Tests

A number of tests are carried out in the laboratory. These are:
 

1)  Soil Classification  (See above)


2)  Consolidation Tests  These enable time/settlement graphs to be drawn so that the rate of settlement and its total final amount can be forecast.


3)  Shear Strength Tests  This is an important group of tests as they indicate the load carrying capabilities of the soils. They are particularly significant in the case of plastic clays as, in these, shear strength is constant at a given moisture content: thus, if shear strength is exceeded, failure is likely.


4)  Chemical Analysis This will indicate the presence of harmful compounds in the subsoil/ground water: these compounds will usually be sulphates or acids. If present they will affect the choice of materials and/or methods; e.g. sulphate resisting or blast furnace cement in foundation concrete; use of separating membrane; use of non‑metallic pipes in acid soils.


5)  Moisture Content Tests  Done as part of the classification test, but also needed to forecast likely volume changes when building on shrinkable/swelling clays.

 

12.1.6 Ground Stabilisation

Before  any work can be carried out it may be necessary to control the ground water and to stabilize the ground. There are a number of ways of doing this and you are introduced to these in the video ‘Ground Stabilization’ video. To learn more about these you can consult the Building Construction Handbook recommended for this unit.

The most common way of stabilising the ground prior to construction work is by the use of Sheet Piling. You were introduced to this in the 'Ground Stabilisation' video although you will get a better understanding of it by watching the videos below. (Note: You can watch the videos full screen by clicking on the icon at the bottom right of the video once playing)

 

Task 12.1.6 Ground Water Control

Provide a brief overview of the methods that can be used to control the ground water and to stabilize the ground prior to construction.

 

 
 
Additional information

If you would like additional information you can visit the constructionsite unit in the column on the left.
 
 
 

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Section 2. Construction Technology

Learning outcome: On completion the learner will: Know the main elements relating to a building and how they relate to each other within a construction project.

 
 
Contents
   
 

12.2.1 Foundations

Foundations are required for a building in order to accept the loads imposed by the building and transfer those loads safely to the sub-strata. 

The type of the foundation used will depend on the building and the condition of the ground on which it is to be placed. You will need to be familiar with the types that are available and the situations in which each type is used.

Foundations must:

• Accept the loads and tension forces from the building structure, and divert and spread them over a large enough area to utilise the maximum allowable resistance of the subsoil.
• To with stand tensional and shearing forces generated by the tendency of the foundation to bend under the opposing forces of the concentrated load of the building from above, and the distributed resistance from the soil below.
• Avoid utilising unreliable or week ground by carrying loads to deeper sound strata or ensure the load is evenly distributed over sufficient area so that the bearing capacity of the soil is acceptable.
• Accommodate ground movement due to swelling or shrinkage which may alter the stresses within the foundation.
• Withstand attack from erosive elements within the soil.
• Be deep enough to be unaffected by climatic changes.
• Provide a level base on which building operations can commence.

 
Type depends on:

• Type of soil/ground
• Depth of suitable strata 
• Water table
• Sub-soil conditions, ie mining
• Heave
• Trees.

Types of Foundations

The following foundation types are in common use. Details relating to each can be found in the Building Construction Handbook recommended for this unit.

Strip
 
 
 
Reinforced Concrete Strip Foundation
 
 

 

 
Trench Fill Foundations
 
 
Pad or Slab Foundations

Stepped Foundations

 
 
Raft Foundations

 
Short Bored Piles


 

• Type of soil/ground
• Depth of suitable strata 
• Water table
• Sub-soil conditions, ie mining
• Heave
• Trees.

 
 
 

Piled Foundations

These are used to support loads transmitted to the subsoil by large buildings as it avoids the need to excavate to solid strata.

Piling should be considered if excavation in excess of 4m is needed.

Piles may be used in the following situations:

• Low bearing capacity of soil for considerable depth.
• High water table which would cause dewatering problems with excavated foundations.
• Compressible layers some distance below the surface.
• Sloping site or sloping strata making strata slip likely.

Considerations which influence choice of pile

• Insufficient area available for spread foundation (e.g. building fills site) but firm stratum and /or adequate skin friction available.
• Unacceptable amount of settlement with spread foundations even though they would not exceed safe bearing capacity.
• Shrinkable clay ‑ building must be founded 1 ‑ 2m down, piles may be the best method.
• Tension forces from overturning (wind or retained material) tension piles a solution.
• Lateral loads ‑ inclined piles can be used.
• Site access available limits rig size.
• Site surface bearing limits rig size unless improvement possible.
• Sloping site limits rig type unless site is first leveled.
• Restrictions above and below ground e.g. headroom.
• Effect on surrounding property and local environment e.g. noise, vibration.
• Programming needs. Foundation time affects total contract time.

 
Types of Piles

Piles function in four ways:

• By taking end bearing on a solid strata at low level.
• By supporting the load by skin friction ( or adhesion ) between pile surface and subsoil.
• By using a combination of the previous two methods.
• By consolidating existing subsoil. e.g. sand piles and vibro piles.

Piles may be: 

• Concrete
• Steel
• Timber

 

They may be classified by the way in which they transmit their loads to the subsoil or by the way they are formed. Thus, they can be classed as

• Precast
• Insitu

or, alternatively they can be

• Displacement ‑ here the pile displaces the soil.
• Replacement ‑ here the pile replaces soil which is excavated.

 

Precast or Preformed Piles

These are driven into the ground by using a pile frame with a heavy weight called a monkey, which is lifted to a specified height and then allowed to fall freely on to the pile head.

Alternatively the pile may be driven by a series of blows from a hammer resting on top of the pile and forced up and down by a steam or internal combustion engine. Driving is continued until the toe of the pile reaches a definite level, such as rock, or until a "set" is reached, i.e. a specific penetration for a given number of blows. Thus a pile may be specified to be driven to set of 25mm for 10 blows with a 3 ton monkey falling 1.2m.

The size of the pile is usually related to their length e.g. a 12m pile will be about 250mm square, while a 24m pile about 450mm square. 

A number of firms hold stocks of reinforced and pre-stressed concrete piles which is useful for a quick start to a job. Common sizes for normal loads are 300, 350, 400 and 450mm square.         

For heavy piling concrete piles are provided with cast iron shoes, because of the stresses induced in driving, the concrete grade and reinforcement must be adequate.

Circular and octagonal section piles may be used for longer lengths. For very long piles steel tubes, box sections or joists are sometimes used in place of concrete piles.


Advantages

• Pile inspection possible.
• Unaffected by ground squeeze.
• Not damaged by adjacent driving.
• Unaffected by water during placing.
• Immediate loading possible.

Disadvantages

• Lengthening difficult for one piece piles.
• Driving damage to pile expensive and may go undetected.
• Driving causes noise and possible damage to property.
• Soil displacement may move walls and alter levels.
• Reinforcement needs are largely governed by handling and driving stresses.

 
Insitu Piles

These can be either Driven or Bored.

Driven

In Driven piles a steel tube is driven into the ground either by a monkey or steam hammer. When it has reached the required depth a cape of reinforcement is lowered into it. The tube is then slowly withdrawn as concrete is placed to fill the hole made by the tube. Variations of this procedure include the use of a concrete tube, built up of sections which are left in place.


Advantages

• Length variation possible without waste.
• Tube excludes ground water.
• Enlarged end possible.
• Economical reinforcement.

 
Disadvantages

• Ground squeeze may damage pile.
• New pile may be damaged by soil movement from adjacent driving.
• Not suitable through water unless liner tube is left in.
• Not suitable in low headroom.
• Noise, vibration and soil displacement, as with precast: but noise not so pronounced if bottom driven type.

Bored

In Bored piles while the casting of the pile is done in much the same way, the tube is sunk into the ground by excavating the material inside it and by screwing or tapping the tube down. The tube itself is formed of short sections screwed together.

For tall buildings which impose a heavy load on the site, the use of large diameter bored piles has become common. Shafts up to 2.4m in diameter can be sunk to considerable depth and the bottom portion reamed out to an even greater diameter. These hole are then filled with concrete and act as columns which carry the load down to soil capable of taking the heavy overall loading.
 

Advantages

• Removed soil can be inspected and checked against subsoil investigations.
• No soil displacement.
• Little noise, no vibration.
• Use possible in 2m headroom.

Disadvantages

• Problems may occur with ground water.
• Concrete not placed under ideal conditions.
• Hole may cave in endangering nearby buildings.
• Excavated material must be disposed of, often involving double handling.

 

Pile Caps

With the exception of large diameter pile or short bored used in housing, piles are normally arranged in groups or clusters. Any load is then distributed over the group of piles by a reinforced cast insitu concrete pile cap.

Structural continuity is obtained by bonding the reinforcement from the piles in the cap, and by the penetration of the pile head into the cap.

The pile caps can be tied together by reinforced concrete beams, these beams can be used to carry walls.

 

Pile Testing

It is normal on a contract to form one pile which is to be tested by overloading it by at least 50% in order to confirm that the design and formation of the chosen pile type is adequate. This pile must be placed where it is representative of site conditions but yet will not be used or interfere with the finished building.


An over view of foundations can be found under multi-media in the column to the left.

 
   
 
 

12.2.2 The Building Envelope

 
Walls

The purpose of a wall is to:

• Enclose space and provide shelter, security and privacy
• Provide support for the upper floor and roof
• Strength and stability – it must be able to withstand all loads applied to it with the structure or loads such as wind.
• Provide resistance to the elements in that it should not be adversely affected by rain, snow, wind or sun and to be able to keep these from entering the building
• Be aesthetically pleasing – it must be acceptable to the occupants and conform to local planning requirements
• Be durable – it must be able to function for an acceptable measure of time without the need for excessive maintenance
• Provide thermal insulation by keeping the occupants comfortable and be able to meet the requirements laid down by the Building Regulations
• Sound insulation – resist the passage of sound within the structure
• Fire resistance – maintain the integrity of the building for a sufficient length of time to allow the occupants to escape to a place of safety in the event of a fire

 

Types of Walls

Walls fall into a number of types though the only ones we are going to look at in this unit are:

• Masonry - which can be:
  • Solid
  • Cavity
• Frame - you should be familiar with the method of construction of a timber frame.

 

Other factors you should be aware of are:

• Bonds – the way bricks or blocks are laid so that the joints are staggered to improve strength and structural integrity.
• Damp Proof Course/membranes (DPC/M) – used to prevent the ingress of moisture into the building.

 

Materials

The material used for walls will be determined by:

• Structural type of building – if the wall is to be load bearing or non load bearing.
• The requirements of the wall - the wall of a recording studio will need special emphasis on sound insulation; a building in an exposed position will need emphasis on weather exclusion and durability.
• Availability - a shortage or long delivery date for certain materials may exclude their use if the building is required quickly.
• Speeds of erection - wet trades normally take longer to construct a building than dry construction.
• Cost - this must not only consider the cost of the materials but also the cost of labour to construct the building.

 

Roofs

This is the part of the building which spans the external walls at their highest point; as it is part of the external envelope it must be able to achieve certain performance requirements.


Performance Requirements

• Weather exclusion. The roof covering must be able to resist the effects of wind, rain, snow, sun etc. in order to protect the occupants of a building, their possessions, and the building itself.
• Structural strength and stability. The means of supporting the roof covering must be strong enough to carry the weight of the covering and any imposed loads such as rain and snow; any workmen who may have to use the roof for maintenance, any storage vessels situated on the roof, and the effect of wind which can cause positive or negative pressures.
• Drainage. All rain falling on the roof must be removed in the most direct way so as to prevent the building from becoming excessively wet.
• Durability. As the roof is the most inconvenient to gain access to, the coverings should not be affected by moisture, frost, atmospheric pollution, and other harmful agents which would cause a failure of the weather-exclusion properties or lead to heavy maintenance costs. Design must cater for the effects of thermal and moisture movement.
• Thermal insulation. Warm air being less dense than cold air, rises, therefore in a heated building the greatest amount of heat loss occurs through the roof, unless suitable precautions are taken. The Building Regulations lay down a maximum coefficient of thermal transmittance for domestic roof construction so that the energy used for heating is not wasted.
• Lighting and ventilation. In large industrial buildings special measures may have to be taken to allow lighting and ventilation through the roof.
• Fire resistance. The roof must prevent the spread of fire from structure to another and maintain its integrity for sufficient period to allow the escape of the occupants.
• Appearance. This must harmonise with the surroundings in order to meet the requirements of the local planning authority. The Planning Authority will consider the shape of the roof, type and colour of covering.

Although there are a number of types of roofs which can be classified by shape, span or structural design we are only going to look at two in this unit:

• Pitched
• Flat

 
Pitched

This is when the slope in any plane exceeds 10o to the horizontal. There are a number of types of pitched roof and these can be seen in the two books below.

The makeup of the roof is governed by the load and span, while the pitch may be determined by the type of covering that is to be placed over the timber carcass.

The timber carcass may be formed in the traditional way or by trussed rafter and you should be aware of both of these types of construction; these can be seen in the book listed above for this unit.
 

Coverings

Pitched roofs can be covered with a number of materials these include slates, tiles, corrugated sheets and thatch.


Slates

Slates are usually made from natural slate and cover many older buildings. They are a dense material which splits into thin sheets.

The slates are secured to the timber battens using nails for each slate. The nails are made of galvanised iron, zinc or copper. The length of the nail will depend on the thickness of the slate.

The minimum pitch on which slates can be fixed is 25o. Slates are laid Double Lap.
 

Double lap roofing

Double lap roofing means that at any point of the roof there will always be two thicknesses of slate or tile covering that point. It will also be bonded so that no vertical joint is immediately above a vertical joint of the course above or below. In order to ensure that this requirement is maintained special tiles are required at verge, eaves, hip and valleys etc. Abutments are made water tight by means of flashings, and by the use of soakers fitted under the tiles. The lap will depend on the pitch of the roof and the exposure.

Tiles are now a more economical type of covering and are widely used. There are two main types:

• Clay tiles. These are either hand or machine made. They can be plain, or interlocking, and come in a variety of profiles and colours.
• Concrete tiles. Similar to clay tiles only made from concrete.

 

Plain Tiling

Plain tiles are laid double lapped as for slates. They should have a minimum pitch of either 45o for handmade tiles or 35o for machine made. Concrete tiles are cheaper than clay though are heavier which can mean larger roof members.

The tiles have a slight camber to prevent water entering by capillary action.

A variety of special tiles are available for hip, ridge and valleys.

The tiles have a slight camber to prevent water entering by capillary action.

A variety of special tiles are available for hip, ridge and valleys.

 

Single lap roofing

This consists of the tiles overlapping at head, base and side. The side lap is determined by the pattern of the tile, though the head lap should not be less than 75mm. These can be used on pitches above 15o, with different types of patterns being used on different pitches.

Tiles are nailed at eaves, hips and ridge and every 4th or 5th row up the slope of the roof.

   


12.2.3 Floors

You should now be able to find your way around the publications listed so see what you can find out about floors. You will have the choice of the following pages to select from:

• Timber
• Ground bearing slabs
• Pre-cast concrete

 

Hollow Block and Precast Floors                        

In certain clay soils the use of solid concrete floors can create difficulties due to ground movement. In order to get round this precast floors can be used which are supported by the walls and therefore do not rest on the soil. This provides a space between the ground and the floor, which can accommodate any ground heave that may result, without effecting the floor.

Pre-cast ground floors may often be specified where:

• the water table is high
• there are aggressive chemicals in the ground
• the ground is likely to heave
• the ground quality is poor and large volumes of hardcore might be required
• the site slopes steeply

 

Beam and Block

One of the most widely used methods is the Beam and Block this is manufactured by a number of companies under different trade names, though the principle is the same.        

It consists of lightweight prestressed concrete joists (which can be easily handled by two men) spanning between the walls to a maximum of 4.5m: Standard building blocks are then used to infill between the joists (See Figure 1 & 2 below).  
Once the blocks are laid the floor can either be grouted and then a 50mm sand and cement screed laid over the grouted floor; or, to eliminate wet trades and increase its insulation value, a minimum of 20mm expanded polystyrene board can be laid directly over the floor (See Figure 3). This should be covered with a 1000 gauge polythene vapour barrier and finished with tongue and groove chipboard.

Alternatively the chipboard can be supported by timber battens placed over polythene, which has been placed on the floor.

The fire resistance of floors constructed by this method is 2 hours.
 
 
Advantages of Beam and Block Flooring Systems

• Easy to handle, quick to install. A three man gang can normally complete up to 200m2 of floor a day.
• Construction not effected by weather, can be laid in freezing conditions.
• Draught proof, rot proof, damp proof and fire resistant
• Reduced preparation, simply remove top soil and vegetable matter prior to fixing floor. Over site concrete not normally required.
• Eliminates backfill and compaction, and reduces the risk of ground heave problems.
• Immediate working platform.
• Cost effective.
• Quality Assurance.

 
The finishes for pre-cast floors are much the same as those for ground bearing concrete slabs. The two most common are the screed and the floating chipboard/strand board floor. In upper floors in flats an important issue which needs to be considered is resistance to impact sound. This normally requires some form of floating floor.

 
 
   
 
 
 
12.2.5 Prefabrication within Construction 
 
Prefabrication may be considered as the assembly of buildings and structures or more usually of their components at a facility (usually a factory) remote from their final position; most components can be preformed; it is the degree of completion of prefabricated units which determines overall advantage or limitations of prefabrication. Prefabrication  can range from an integrated door set to a completed building.
 
Prefabrication requires meaningful design co-ordination from all personnel involved in the design and build process and usually results in the standardization of  form and materials.
 
Many systems of construction are based upon system building and prefabrication and it should not be considered that prefabrication is limited to buildings; many of largest structures such as bridges and dams are prefabricated or part prefabricated to aid on site construction. Services may be incorporated into prefabricated units. 
 
Prefabrication is not a modern innovation it has always been part of the construction process but it is the advent of modern machinery for moving and lifting components on site and the modernization of machinery and factory production techniques which have promoted and enabled the prefabrication of large and integral units.
 
The ‘izations’ are fundamental in the development of prefabrication the list will include:

• Standardization of components and systems
• Rationalization of components. -  Limiting the components used within the production process or required on site.
• Mechanization of production on and off site - machines and robots   
• Industrialization of the production process – a factory environment.
• Computerization of production techniques within mechanized production.

 
All combined with:
 
Research and Development of existing systems and production methods to increase the effectiveness and efficiency of the ‘izations’ 
 
Examples of the advantages of Prefabrication within construction include: 

• The factory programme and construction site can work together in ensuring production is co-ordinated to use ‘Just in Time’ delivery. 
• Components produced by machinery and computer control have a high degree of accuracy.
• Workmanship and consistence of the product are improved.
• Prefabrication removes many of the constraints due to weather conditions.
• Repetitive construction should result in familiarization with the product and working practices resulting in increased productivity.
• Labour can be trained within the system thus skilled labour is not always required.
• Waste should be minimized due to production techniques. 
• Improved Health, safety and welfare within the factory and by familiarization with the product.
• Method statements and risk assessments will become standardized and better understood by the operatives.
• Improvement in on site programmed times.
• The quality of the product is improved.

 
 
Examples of the disadvantages of prefabrication include: 

• Larger often heavy components must be transported and erected using mechanical means. 
• Machinery must be matched to the components to be erected and must be available when required.
• Co-ordination of delivery and erection must be well managed or suitable storage provided.
• Mistakes in production are repeated many times before they are recognized on site which is costly.
• The detail drawings must be accurate to ensure that production teams can work from them.
• It is more difficult to use prefabricated components within, and when meeting with, existing structures. 
• Issues can arise with the carbon footprint when components are transported over long distances. 
• High initial cost in establishing the production facility, specialist equipment and machinery. 

 
   

 

12.2.5 Internal Finishes

This consists of internal walls, floors, stairs, ceilings, joinery and finishes.

Internal walls are used to divide up the internal space. Walls can be of solid construction such as blocks or timber stud partitions or proprietary systems. These are then covered with a wall board such as plasterboard which are then finished by coats of plaster or by the use of a dry lining system. Finishes will depend on the use of the building with consideration being given to the function of the room i.e. a lounge may be papered or painted whereas a bathroom may be tiled.

Floors were looked at above although the finish to the floor will, once again, depend on the function of the room, which will dictate if it is to be finished with tiles, timber veneer or carpeting.

Ceilings can be boarded and plastered or suspended ceilings, the latter being used for commercial buildings as they allow for service runs to be placed for easy access yet hidden from view.

Details of these and other items can be found in Section 6 of the recommended book for this Section specified above.

 

12.2.6 External Works

During the construction of a building, consideration will need to be given to the arrangements for bringing services to the building and for the removal of soil and waste. This will involve the construction of service runs and the means of getting people and vehicles to the site resulting in the need for roads and footpaths.

On completion work will be carried out to landscape the site ensuring it is aesthetically pleasing prior to the hand over to the client.


   
     
  
 

---

Section 3. Management of Construction

Learning outcome: On completion the learner will: Know how to ensure the project meets requirements.
 
 
 
 
Contents
   
 

 

12.3.1 Ensuring products and materials meet the needs of the project

One of the main factors in ensuring that the products and materials meet the needs of the project is through the process of Quality Control. It is important that you are able to interpret and understand quality requirements relating to the products and materials in order to ensure that they meet the needs of the project. The information relevant to quality will come from a number of sources and the site manager will need to ensure that any work carried out conforms to the requirements specified. It will also enable liaising and discussing quality control matters with other members of the construction team, these will include the Architect, Civil Engineer, Clerk of Works, site staff, tradesmen etc.

The client demands that the finished products, which includes materials and workmanship is of an appropriate acceptable standard which conforms to their requirements.

Companies can spend substantial amounts of time and money carrying out work which is unacceptable to the client, this results in additional time and expense putting things right. By reducing this you will improve profitability and improve competitiveness.

 

Clients’ (Customers’) Requirements

The client will expect that the completed project conform to their requirements.

Quality is not just concerned with production but all of the processes that involve a business; consequently it will apply equally to people within your own organisation and those receiving a service from you so it is appropriate to look at all everyone who is in receipt of your services as a customer. The way to achieve this is to:

• Understand the requirements of your customers
• Understand the internal process which enables you to meet these requirements, and
• Develop a system and culture that ensures errors are eliminated.

 
Companies spend substantial amounts of time and money doing the wrong things and putting things right after they have gone wrong. By reducing this you will improve profitability and improve competitiveness.

 

Customers' Requirements

These are divided into two key areas:

1. Defined requirements - these must be met by the delivered product or service. They are often specified in the contract and may include some or all of the following:

• size, weight, colour, texture
• functions, reliability, response times and facilities required
• packaging, labelling, delivery time and methods
• cost and payment arrangements
• support required
• response time to failures.

These are the basic requirements for each product or service. They are the minimum client requirements which must be met if a product or service is to be considered satisfactory.


2. Implied requirements - these are unstated, but create an overall perception of your business in the eyes of the client. It is the little things that show you care for your customer. These include:

• Keeping them informed
• Consideration for their convenience
• People responding to enquiries/problems.
• Visitors made to feel welcome
• Professional correspondence
• Meetings are punctual
• Information is available if the client has a query.

 
 
 

12.3.2 Ensuring the project meets the designed objectives and requirements

Ensuring that the project meets the designed objectives and requirements relates to two aspects:

• That it is able to function and provide the facilities that the client requires
• It meets all the statutory requirements.

 

Facilities

This is mainly the responsibility of the designer although the site manager must ensure that the building is produced according to the specification provided

It is imperative that what is required and the quality requirements are conveyed to all the members of the team and that all workers fully understand the standards that are demanded. These standards relate to:

• Appearance. The appearance must be acceptable to the client according to the use of the building and the people that will be using it. If the building is to be a 5* hotel it will need to be more aesthetically pleasing than if it is to be used for storage. This is the area where most disagreements can occur as what look good to one person may not to another.
• Performance. The project must be able to perform to the standard that is required of it. If it can’t do that it is not acceptable. It must be ‘fit for purpose’.
• Structural soundness. This is a case of either it is or it is not and obviously it must be structurally sound.
• Dimensional accuracy. Tolerance will be determined which will depend on client requirements or working practice. These are easy to assess.

 

Requisites

This must consider:

• Performance – Considers what it must do.
• Reliability – It must be able to perform for a reasonable period of time without failure.
• Conformance – This is the degree to which specification is met.
• Durability – This is the length of time a product lasts before it needs to be replaced.
• Serviceability – looks at the service that the product gives, the amount of repair that may be needed and the time taken to repair.
• Aesthetics – This is how the product looks and feels.
• Perceived quality – This can be subjective judgement that results from image.

It is essential that all craftsmen are appropriately trained and qualified and also that they are briefed as to what the client requires. Failure to ensure that this happens can lead to work not being accepted and the redoing of work. It can also result in litigation something which it is advisable to avoid. All these will result in costs which can reduce the profit for a contract.

Ensuring that the work is of an appropriate quality is the job of all people involved in the construction process. Each worker should be aware of what is acceptable and any work that does not meet that standard must be redone. The way it is monitored is through the supervisors, site managers, clerk of work and architect/project manager.

 

Statutory Documents and Requirements

A number of statutory documents exist in order to ensure that work is produced according to specified standards. Therefore the site manager will need to be familiar with the following documents in order to ensure that quality is of a required standard according to law, although this is a minimum standard and the standards will vary according to the type of work and client requirements, all of which are set out in the contract documents. Although not statutory documents in respect that they are legislation they are legal documents which are enforceable by law as they form part of the contract in the carrying out of the work. The documents below will provide information and lay down the requirements with regard to quality:

• Building Regulations
• British Standards
• Agrément Certificates
• Contract Documents
• Contract Drawings
• Technical Specifications
• ISO 9000

 


Building Regulations

The Building Regulations have developed over the years to ensure the safety of those who come into contact with buildings.

The Building Control Officer will inspect the work during the course of construction in order to ensure that it complies with the requirements. Alternatively, for housing developments the National House Building Council (NHBC) may be used as the approved inspector (someone qualified to carry out the task of confirming that the building is constructed according to the Building Regulations).

Inspection of the work must be carried out by an Approved Inspector who must be informed 48 hours prior to commencement of work. S/he will then require 24 hours notice to inspect at the following stages:

• Excavation for foundations
• Foundation concrete placed
• Damp-proof course in position
• Oversite fill material in position
• Drains laid
• Drains back filled

 

This will ensure that the work meets the required standard. The inspector may use visual inspection to confirm compliance or they may, as in the case of drainage, carry out tests.

If an Approved Inspector is used S/he will submit an initial notice to the Local Authority with the drawings and evidence of insurance. If the Local Authority accepts the notice it becomes the Approved Inspectors not the Local Authority who are responsible for the enforcement of the regulations. On satisfactory completion the Inspector issues a certificate to the developer and the Local Authority.

 

British Standards Institution (BSI)

This was set up in 1929 to co-ordinate the efforts of all manufacturers and people associated with the use of products. It lays down standards for the improvement, standardization and simplification of all materials. It also lays down standards of quality and dimensions.

There are five kinds of documents produced by the BSI which are:

1. British Standards – These were initial product specifications, but now they include schedules, methods of testing, basic data. The standards are laid down to ensure that quality, performance and usability of components are met, and also lays down preferred forms of a product and properties of a finished article, and method of testing for verifying that the standard has been achieved. There are BS standards for most of the functions and products related to the construction industry.
2. Codes of Practice – These are recommendations for good practice to be followed during design, manufacture, construction, installation and maintenance with regard to safety, quality, economy and fitness for purpose.
3. Draft Documents – These are used before British Standards are issued where firm standards cannot be issued due to the lack of information on the introduction of a new idea of subject. They are intended to be used for a limited period until sufficient data is collected to enable experience, knowledge and usage to contribute to the production of a British Standard.
4. Published Documents – These are publications used until sufficient information is obtained; they are normally used for subjects which cannot fit into other group categories.
5. Drafts for Comment – These are issued when the BSI is convinced that a subject is important enough to provide resources to look into the preparation of a BS. Anyone can request a new standard and the Institution will then produce a number of drafts for comments. Once these have been considered a British Standard can be introduced.

  

Agrément Certificates

The British Board of Agrément is a government sponsored organisation which is also financed by the manufacturers of new products. The manufacturers obtain an independent test certificate from the Board which will when approached will test the product. The certificate is widely recognized and accepted by industry.

 

ISO 9000

ISO 9000 is:

• An internationally accepted standard relating to a quality system. Also known as BS5750 in Britain or EN29000 in Europe.
• It is a formal management system which is adapted by individual companies to meet their needs.
• It has been broken down into a number of headings to enable it to be easily and efficiently implemented.
• It is flexible enough to enable it to be implemented by any type of organisation.

 
 
 


Eco, green, low carbon construction
 
Eco, green, low carbon; are all terms used to describe (sometime incorrectly) technology or processed of production which substantially reduce the need for power created from the use of fossil fuels.
 
All aspects of fossil fuel use is included in determining eco- friendly construction criteria; this will also consider the transportation of materials using fossil fuels which will result in a negative impact on the environment by the production of carbon dioxide and similar harmful emissions. 
 
Eco-friendly forms of construction recognise the negative affect that many traditional buildings and structures have on the environment and the excessive demands they can place on fossil fuels. The ideal eco-friendly building would have no harmful effect on the environment and be resource neutral; a building which meets this criteria throughout its materials production, on site construction and working life would be difficult to produce; however the overall objective of eco-friendly construction is to produce a form of construction with materials which are locally sourced and renewable and once the building is complete relies on renewable sources of energy without reverting to any form of fossil fuels.
 
The reader will be familiar with many of the innovations now in popular use in order to reduce dependence on fossil fuels and thus reduce or prevent emissions which are harmful to people and the environment. These include:

• Solar Panels
• Water conservation and recycling
• Efficient and extensive insulation
• Bio-fuels from renewable sources
• Water based paints and finishes
• Low energy lighting

 
 
The sources energy by means which produce of low carbon emissions may be considered as:

• Nuclear power
• Wind power
• Solar power
• Geothermal power
• Tidal power
• Hydro-electric 

 
However whilst they do not consume fossil fuels in the production of energy many of the above will consume large amounts of energy during the manufacturing and construction phases and require maintenance and repair during their working life. 
 
In reality the advantages and disadvantages of all forms of energy conservation and the reduction of carbon emissions requires a balance to be achieved between all aspects of manufacture, transportation, cost in construction, cost in use and eventual recycling and decommissioning.   
 
Within building construction the Building Regulations state minimal requirements.
 
Other topic areas directly related to green technology include:

• Sustainability
• Waste management
• Re-cycling
• Pollution and contamination - reduction and prevention
• Climate change 
• Protection of the natural environment
• Earth rammed structures.
• Straw bale construction.
• Re-cycled car tyre structures.

   



12.3.3 Managing remedial work


Identifying and Correcting Defects

Part of the system to monitor the quality of work is to identify the areas where defects can occur and to instigate measures which address the problems that can result in these areas. It also involves the assessment and rectification of any faults that are found. They key thing is that all quality standards meet the requirements specified in statutory documents and in the contract.

 

Conforming to Contract

A number of clauses in the Conditions of Contract have an influence in the way that work is carried out and the quality of the finished project.

The contract will specify that the work must comply with all statutory regulations and the specification of the work should result in a building that achieves the required standards and quality. The contract also provides for inspection of the work, goods and the materials both on and off site. The contractor is responsible for ensuring that competent tradesmen are employed.

A clause covers levels and setting out of the work and for the uncovering of work for inspection if the architect feels that is necessary.

 

Setting out

In order to set out correctly the architect should provide the contractor with all the necessary information in order to set out correctly. This will be in the way of dimensioned drawings and levels. Provided the dimensions are correct, the contractor is responsible for ensuring the building is set out correctly and he would be liable for any errors.

 

Work, Materials and Goods

This clause in the contract ensures that the quality of materials and workmanship will conform to the contract bills and relates to the information contained in the BofQ. The contractor must, if required to do so, prove that the materials being used are in accordance with the specified requirements.

Proof of materials can be shown by producing invoices or by tests which would be specified in the contract bill. If the architect requires tests which are not specified in the contract bills these must be carried out by the contractor, the cost of which would be added to the contract sum.

The architect has the power to request the inspection or test of any part of the work up to the issue of the final certificate. This may require the contractor to open up the works for inspection or testing. The cost of opening up the work will be borne by the contractor if the inspection or tests show it is not in accordance with the contract. If it is in accordance then the cost will be added to the contract sum.

The architect also may require materials that do not conform to the contract to be removed from site and be replaced by those that do, the cost of this would be borne by the contractor. There is no time limit for defect materials to be discovered.

 

Check Lists

One of the most common and efficient ways of ensuring that work is produced to an acceptable standard is through the use of check lists. These enable all work to be assessed against a standard and to require action if it does not meet those standards. This will also provide the documentation to enable the process of remedial action to be monitored and managed.


 
 
 

12.3.4 Legislation Controlling Buildings of Historic Interest
 
A number of pieces of legislation exist in order to protect buildings of historic interest.  This may be due to their historic implications or type of construction.
 
 
Heritage Legislation

• Ancient Monuments and Archaeological Areas Act 1979, as amended by the National Heritage Act 1983 
• The National Heritage Act 1983 established the Historic Buildings and Monuments Commission of England, more commonly known as English Heritage / National Heritage Act 2002 
• Planning and Compensation Act 1991
• The main legislation concerning archaeology in the UK is the Ancient Monuments and Archaeological Areas Act 1979. 
• This Act, building on legislation dating back to 1882, provides for nationally important archaeological sites to be statutorily protected as Scheduled Ancient Monuments. 

 

Ancient Monuments
 
Ancient Monuments are structures of special historic interest or significance, and range from earthworks to ruins to buried remains. Many of them are scheduled as nationally important archaeological sites. 
 
If any ancient monument could in any way be affected by proposed development, advice from English Heritage should be sought as soon as possible. 
 
 

The Schedule of Monuments
 
'Scheduling' is shorthand for the process through which nationally important sites and monuments are given legal protection by being placed on a list, or 'schedule'.  English Heritage takes the lead in identifying sites in England which should be placed on the schedule by the Secretary of State for Culture, Media and Sport.  Scheduling is the only legal protection specifically for archaeological sites. A schedule has been kept since 1882 of monuments whose preservation is given priority over other land uses. The scheduling of a monument means that permission is required for works affecting that monument.  It is an offence to damage a scheduled monument.
 
 

Which sites are monuments?
 
The word 'monument' covers the whole range of archaeological sites. 
 
Scheduled monuments are not always ancient, or visible above ground. There are over 200 'classes' of monuments on the schedule, and they range from prehistoric standing stones and burial mounds, through the many types of medieval site - castles, monasteries, abandoned farmsteads and villages - to the more recent results of human activity, such as collieries and wartime pillboxes.
 
Scheduling is applied only to sites of national importance, and even then only if it is the best means of protection 
 
 

Criteria for National Importance
 
Decisions on national importance are guided by criteria laid down by the Secretary of State for Culture, Media and Sport, covering the basic characteristics of monuments. They are:

• extent of survival 
• current condition 
• rarity 
• representivity, either through diversity or because of one important attribute 
• importance of the period to which the monument dates 
• fragility 
• connection to other monuments, or group value 
• potential to contribute to our information, understanding and appreciation 
• extent of documentation enhancing the monument's significance

 

The Effects of Scheduling
 
A monument which has been scheduled is protected against disturbance or unlicensed metal detecting.  The Secretary of State must be informed about any work which might affect a monument above or below ground, and English Heritage gives advice to the Government on each application. 
In assessing each application the Secretary of State will try to ensure that damage done to protected sites is kept to a minimum.
 
Written consent must always be obtained before any work can begin. 
 
 
Alternatives to Scheduling
 
Even nationally important sites are scheduled only if this is the best means of protecting them. 
In town and city centres, the best way to protect sites - from building development and road schemes - is to use the system of local authority control over planning applications. 
 
Buildings and standing structures of historic interest, especially if they are or can be made usable, are generally best protected by listing, where the emphasis is on continuing active use
 
 
Listing
 
Listing is used to protect the best of our architectural heritage.  When buildings are listed they are placed on statutory lists of buildings of 'special architectural or historic interest' compiled by the Secretary of State for Culture, Media and Sport under the Planning (Listed Buildings and Conservation Areas) Act 1990, on advice from English Heritage. Listing is not intended to fossilise a building.
 
A building's long-term interests are often best served by putting it to good use, and if this cannot be the one it was designed for, a new use may have to be found.  Listing ensures that the architectural and historic interest of the building is carefully considered before any alterations, either outside or inside. 
 
All buildings erected prior to 1700 and substantially intact are listed. Most buildings constructed between 1700 and 1840, although some selection does take place.  The selection process is more discriminating for buildings erected since 1840.
 
 
Criteria used to determine Listing

• architectural interest: all buildings which are nationally important for the interest of their architectural design, decoration and craftsmanship; also important examples of particular building types and techniques, and significant plan forms 
• historic interest: this includes buildings which illustrate important aspects of the nation's social, economic, cultural or military history 
• close historical association with nationally important buildings or events 
• group value, especially where buildings comprise an important architectural or historic unity or are a fine example of planning (such as squares, terraces and model villages)

 
The older and rarer a building is, the more likely it is to be listed. 
 
 
Grading
 
Listed buildings are graded to show their relative importance:

• Grade I buildings are those of exceptional interest 
• Grade II* are particularly important buildings of more than special interest 
• Grade II are of special interest, warranting every effort to preserve them

 
 
The Control of Development
 
A Listed building is immediately protected by law, and any changes to it must first receive listed building consent. Any alterations must respect the character of the building, and that the case for its preservation is fully taken into account when any redevelopment proposals are considered. 

The system of listed building consent is a flexible one: over 90% of applications result in permission being granted. The owner of a listed building has to apply for listed building consent to the local planning authority. 

Local authorities have control over minor changes to listed buildings, but have to notify English Heritage (EH) when they first receive applications affecting buildings of outstanding national interest, normally those listed Grade I and II* English Heritage advises local planning authorities and the Secretary of State for the Environment, Transport and the Regions on the most important applications. Some authorities also let EH know of applications involving full or partial demolition of Grade II buildings. They must also notify EH of proposals involving their own buildings. 
 
 
Conservation Areas
 
The first conservation areas were created in 1967, and there are now over 8000 conservation areas in England. Character of these areas does not come from the quality of their buildings alone. Conservation areas give broader protection than listing individual buildings: all the features, listed or otherwise, within the area, are recognised as part of its character. 
 
 
   
 

12.3.5 Systems to sign off the completed work.


Assessing, Recording and Resolving Work Problems

It is normal to have some form of procedure which will assess the work carried out. This will involve periodic checks as the work progresses and on completion such as ‘snagging’. The procedure will have predetermined factors to look at which will be recorded on an assessment form. In the event of something not being acceptable a procedure will be in place to bring it to the attention of the person responsible in order that they can rectify it.

It is always worth considering why the work is not acceptable and then at how the problem can be rectified. Some common problems are listed in the table below together with suggested solutions.
 

Common Quality Problem	Suggested Solutions
Staff make mistakes because they have not been probably trained.	Ensure that everyone knows what their job is and how to do it.
Different people make the same product in their own way, causing variations in product quality.	Adopt best practice in doing a job and constantly use it.
People produce the wrong goods because they are using an out-of-date specification.	Ensure that everyone uses the current version of a document
Mistakes are made because the right person wasn’t involved in a decision.	Specify who will be responsible for quality.
Different departments do not talk to each other.	Ensure communication and co-operation between staff.
People don’t see quality as their responsibility.	Place responsibility for quality on those who produce the product.
Faulty products are delivered to the customer.	Carry out proper inspection checks.
When found, mistakes go uncorrected, and the same mistakes are regularly made.	Analyse product faults, correct them, and try to prevent them happening again.

Quality Plans

A quality plan can be produced to define:

• working methods and procedures
• standards for deliverables
• standards for supervision and review
• project checkpoints
• user involvement.

The plan is used to improve and assure the quality of the project and will involve the following:

• Setting Objectives. Set out what you want to achieve and the standard of quality that you expect from the product or service that you are trying to produce or the initiative that you are undertaking.
• Assessment. Determine how these objectives will be assessed and how you will confirm that the requirements have been achieved. The objectives should be Specific, Measurable, Achievable, Realistic and Timely (SMART).
• Quality plan: The plan puts in place quality assurance processes to ensure that the desired quality is achieved and tests to provide evidence. Quality planning should demonstrate that the outputs meet the objectives and criteria in a straightforward and neutral way.
• Implementation: This lays down what is to be done, by whom and when.
• Evaluation: Measure the success of what you set out to do. For a project or programme, this tends to relate to achievements, outcomes, what was learned and how this changes things.

Management must give a clear lead on setting standards and in ensuring that they are attained. This is particularly important when incentive schemes, based on output, are employed.

 

Handover of Project

Prior to hand over of the project the contractor will need to ensure that all the work is completed to the satisfaction of the client and that all necessary tests and approvals have been obtained.

The process then involves the client or his representative walking round the project to confirm that they are satisfied with the product or to point any any items which the contractor will need to rectify.


 
 
 

 

You have now completed Unit 12, and you should complete the assignment and send it to info@gatesmacbain.co.uk.

When submitting your assignment you should ensure that it meets all the requirements set out on the Submitting Assignments page, which is accessible from the Student Area or towards the top of the column at the left of this page.

If it does not conform in all respects it will be returned to you and not sent for assessment resulting in delay. ALL questions must be answered in your own words.  Any indication of plagiarism will mean that the assignment will fail and be returned to you.
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You will be notified as soon as it has been assessed, which will then enable you to continue.




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