PRELIMINARY SITE WORK

Prepared by:Mr. B. ElliottBTCMS2011

• Accessibility

• History

• Climate

• Soil type

• Availability of

services

• Zoning

• Regulations

• Cost

• Topography

• Aspect

• Size

1. FACTORS AFFECTING THE CHOICE OF A BUILDING SITE.

EXPLANATIONS

• Cost – how reasonable is the cost per square

foot or meter of the chosen site. It is

normally associated with1. Level of development

2. Available amenities- health/educational facilities,

utilities, public transportation, recreational facilities

& shopping centers 3. Location4. Demand5. Zone6. topography

• Topography-the shape of the surface of the

land. This is sometimes referred to as

‘contour’ and can be: flat, undulating, gently

sloped or steeply sloped.

• Boundaries-this must be established and

supported by a survey drawing before the

actual size of property can be ascertained.

They are normally marked so they can be

easily identified or re-established. Reference

for these markers is called a datum.

• History-the study of pass events

associated with the use of the site:

Water (natural watercourse, springs or

flooding); Dump (whether the site was ever

used as a dump); Original topography (was

the land filled); Others problems (old

foundation, underground lines such as gas,

electric or telephone or trees recently

removed to accommodate construction.

• Ownership-certified by a deed (legal

document) must be established

before any final decision is taken

regarding sale/purchase of land.

Transfer can only be done between

rightful owner and purchaser.

• Shape – the shape of the lot (plot)

must reflect the proposed shape of

the structure within the framework of

the legal restrictions. E.g. Lot too

narrow, acute, sharp or too many

corners.

Proposed building

Legal limit

street

Limiting position

Maximum possible size of building

Street

LOT TOO NARROW

CORNER MAY BE TOO ACUTE/SHARP OR THERE MAY BE

TOO MANY CORNERS

• Soil Type – prior to designing the

foundation for a building the

properties of the subsoil must be

assessed. This includes:

1.suitability of the site for the proposed

project, and

2.classification of soil type (silt, sandy,

clayey, etc.)

• Accessibility – Is there easy access to

the site for the transport of materials

and other services. All lands not

adjoining a street or public pathway

requires some means of access. This

access influence movement to and off

site during the construction stage as

well as during occupancy.

• Zoning-the legal identification of the land for

specific use. It is categorized as:

• residential,

• commercial,

• industrial,

• Agricultural

The purpose of zoning is to assist land

developers or owners in recognizing land for

use as well as provide information or guidance

about the character of the neighbourhood

• Size - size of building lots are usually

specified in order to ensure that:

1.Legal requirements of setback and off set

distances are satisfied

2.The building should occupy the maximum

percentage of the total land area as specified

by the local authorities for the prescribed

zone.

3.A reasonable size of building is proposed.

Specifications are outlined in the planning regulations

LOT 3

Center of street

A – off set Distance

B – Front Set Back

C – Rear Set Back

B (5m)

A

3m

A

C

Figure showing setback requirements

2. REASONS FOR STRIPPING A BUILDING SITE

• Reducing instability of top soil

• The removal of all vegetation such as

bushes, trees and scrubs.

• The digging out and clearing away of tree

roots.

• The demolition of existing buildings

• The removal of soil to reduced level.

• Removing boulders, stones and rubble

• To remove termite nests

• To produce a sound and level platform

3. HOARDING

• Under the highway act a close boarded

fencing must be erected prior to the

commencement of building operations if

such are adjacent to a highway or public

footpath. Hoarding is part of the

temporary close boarded or open

boarded fence or barrier erected/installed

on a construction site

REASONS/PURPOSE FOR HOARDING

- Public protection

- Material/equipment protection

- Security

- Reduces vandalism

- Prevents interruption and interference

- safeguard the work in progress

- To keep out stray animals

- Safety

EXPLANATORY NOTES FOR REASONS GIVEN

• Public protection – to reduce the risk of

accidents by keeping activities on the site

away from outside persons. protect the public

from possible hazards from the site such as

dust, falling objects, moving equipment and

noise

• Material/equipment protection – to reduce

theft of materials.

• Reduces vandalism – prevents persons

from interfering or destroying items on the

site.

• Security – to ensure workers and

equipment are safe on the site as well as

protection against theft and vandalism of

materials and installations.

• Prevents interruptions and

interference – persons or animals from the

outside would not be able to distract

workers on the site.

• Safety – enclosing the construction area to

protect passers-by/public against injury

during any construction work. It assists in

guarding against litigation

• To keep out stray animals – to prevent

animals from falling into excavation trenches

or damage trenches.

• Control – to reduce the movement of

workers and avoidance of unwarranted

interruptions and distractions. Activities

should be carried out with minimum

inconvenience. The movement of supply

vehicles and the receipt of goods should be

planned and controlled at all times.

SITE ACCESS

• Access to the site is usually by a pair of

gates. Typically, the entrance should be 12

feet to16 feet (3657.6mm to 4876.8mm)

in width. The gates are normally hung to

open inwards so that they do not obstruct

the foot path or public highway.

• Barricades are normally put around a site

to prevent unwanted access.

• Signs are placed at strategic points for

proper directions to wanted and unwanted

personnel.

• Lights provide illumination at nights to

prevent accidents or unwanted access.

TO ALIGN A TEMPORARY FENCING.

• Plumb the two posts at either end of the

fence, stretch two builders lines between

one near the top and the other near the

bottom of the posts.

• The post should be positioned upright in the

hole after which you should use a spirit level

to ensure that it is vertical.

• The appropriate spacing for the postholes

is between 1.8m and 3m centers

• The depth of a post into the ground should

be 600mm for fences up to 1.2m in

height.

• The depth of the post into the ground

should be 750mm for fences up to 1.8m in

height

4. LAYOUT SIMPLE BUILDINGS/STRUCTURES

• In laying out of a simple building, you

must be conversant with the legal

considerations as well as the actual

layout practice.

LEGAL CONSIDERATIONS

• This is necessary to avoid genuine mistakes

and possible mistakes. Such considerations

involve:

i. Boundary lines – the survey map will show

the actual size of the lot by identifying the

boundary lines. During layout, the first set of

distances (measurements) would be

developed from these lines.

ii. Codes and regulations – (see “size” in

factors affecting choice of site)

iii. Permits - this refers to the written consent

granted by the local authority. Permission is

normally required by a contractor before

the start of any construction works.

iv. Building Line – this is a line measured

from the center of the road which no part of

the building should exceed.

METHODS

• Considering the actual layout of the building,

it is necessary to be conversant with the

tools and equipment before actually

beginning with the layout.

• Tools & Equipment – tools and equipment

used for laying out buildings vary according

to the builder’s resources, as well as nature

and scope of the project. These tools

normally include:

i. For squaring corners – Builders square,

framing square, 3,4,5 or 6,8,10 Pythagoras

method (using tape measure), optical

square or site square.

ii. Measuring – measuring tape or chain

iii. Elevations – line & plumb bob, aqua level,

laser level, spirit level, line level, surveyor’s

level

iv. Identification – stakes and sledge hammer

TECHNIQUE FOR LAYING OUT

• The most essential aspect of a simple

layout is establishing the corners of the

proposed building.

• Building corners – a copy of the plot plan

for the building should be available before

layout is approached.

a) Find out the distance from the site

boundary to the building line on the

working drawings. A line is first

established from the set back distance

to the front of the property line.

b) Use the tape measure to measure the

same distance from the site boundary to

the location of the building line on the

ground.

Select a corner on the ground to be

corner “A”

c) The corner is then identified and

staked using the off set distance from

the side property line.

d) Repeat the same step to place a peg in

the ground for corner “B”

STEPS USED IN LAYING OUT OF A BUILDING

Step 1:

• Locate profile boards (or batter boards) at

approximate floor level height, using a spirit

level/line level and chord line, to ensure that the

profile board around the entire perimeter are

accurately levelled. Profiles must extent a minimum of

2’ outside building dimension.

Step 2:

• On these profile boards the shape and exact

dimensions of the building will be marked.

Step 3:

• Mark the positions of walls, foundations and

ensure squareness. Locate the position of wall

and foundation on first set of profiles, marking

with pencil, nail or saw cut.

 Step 4:

• Locate second and subsequent walls and

foundations using lines and:

• Mason’s square

• Builder’s square

• The 3:4:5 method

Step 5:

• To mark out the foundation, locate lines in

the position marked on the profiles for

foundation.

• Use a trail of sand, spray paint or other

suitable material to mark out the position

of foundation on ground in preparation for

excavation.

Marking out foundation (single nail) and wall width (double nail) on batter board.

Marking out foundation (single nail) and wall width (double nail) on batter board.

• The 3:4:5 method: any combination of the ratio

will ensure a square corner. Example, using a long

tape and setting out triangle with sides e.g. (15’ x

20’ x 25’)

•  To check the accuracy and squareness of the

laying out (setting out), the diagonal method

may be used.

  To do this, use a long tape to measure both

diagonals. Their measurement should be the

same. If they are not, re-check the squareness of

each corner and the measurement of each wall

length.

THE DIAGONAL METHOD for checking squareness of building

3:4:5 method for checking squareness of corners

Setting up profiles for a L-shaped building

Profiles

Figure showing profile/batter board

Sloping sites

• When laying out on sloping site or

obstructed lands, all measurements should

be level. Pegs, stakes or posts are

positioned on, or driven into, the ground to

act as intermediate measuring stations.

Ideally, batter boards should be

constructed from the highest elevation

point.

stake

Leveled tape

Measure distance

Profile board

Projected distance

Plumb bob

stake

Ground level

• Site office – normally provided for large

projects to house the general foreman and his

clerical staff as it is the communication center.

It also assists in the daily administration of the

project.

• Changing room and sanitary facilities – to

ensure the cleanliness of the workers and the

worksite

• Workshop – to assist carpenters, steel benders

and other trades men in their work.

5. REASONS FOR TRMPORARY SHELTERS

• Tool & Equipment storage- trades men

are normally required to carry and secure

their own tools. The main contractor for

expediency and for special purposes may

find it necessary to carry a supply of

special tools and equipment which would

be available to the workmen. It also

carries other items that can only be

released on special issue such as locks,

paints and small tools.

• Material storage – this is provided to

protect materials from theft or damage. Such

store would carry materials such as

reinforcing steel, rough lumber, tiles and

cement.

• Store room – to store and organize materials

• Warehouse – use for the storage of delicate

components and fittings such as doors,

windows, light fittings, receptacles, electrical

and plumbing appliances etc.

6. PURPOSES OF TEMPORARY SERVICES

• Temporary services relate to the provision

of utilities for the purpose of facilitating

construction activities as well as providing

conveniences for workers such as toilet

facilities, drinking water and adequate

lighting. These supplies normally include

gas, water, compressed air, electricity and

telephone.

Conveniences• These include conveniences for personnel and work

process.

Personnel

Provision under the factories act allows for provision of

certain conveniences for workers. Temporary services

assist in the provision of drinking water, adequate

lighting and toilet facilities. Drinking water and toilet

facilities should be positioned for quick access thus

reducing idle time.

Work processes

• Utilities supplied to the site can be used to

drive (power) plant and equipment or

provide ingredients for preparing certain

materials. Examples of supplies used for

driving plant and equipment are:.

• Telephone – to order material, emergency,

communication.

Work processes CONT’D

• Water – mixing concrete, drinking, washing

hands, sanitary purposes, bathing

• Gas and oil – turbine and hydraulic tools

and equipment, heating

• Electricity – electric tools, machines and

equipment, lighting for site in the night

• Heat – asphaltic processes

• Air – use to operate pneumatic tools

and equipment, spray painting,

excavating and compacting

Communication

• Communication includes physical and verbal

contact between the agencies and processes

during the life of the project. Factors to be

considered in communication are temporary

roads for access to the site and storage areas,

as well as possible telephone or two way radio

contacts for placing orders and dealing with

routing administration and contingencies

which are important.

TEST YOUR KNOWLEDGE

Obj. 1. List THREE factors to consider when selecting a

building site

Obj. 2. State THREE reasons for stripping a building

Obj. 3. State FOUR reasons for hoarding a building site, and

write brief explanatory notes on any THREE of the reasons.

Obj. 4. Name and sketch TWO methods of checking for

squareness when setting out a building.

site.

Obj. 4. Explain (with the aid of sketches,) how

a. To install profile boards when setting out a building

b. Squareness should be checked after setting out a small

building

Obj. 5. State ONE purpose for EACH of the following

temporary shelters on a building site

a. Site office

b. Sanitary facilities

c. Storeroom

Obj. 6. Explain the purpose of EACH of the

following temporary services on a building site.

a. Water

b. Electricity

c. Telephone

d. gas

1. The first task in setting out a structure is usually toa) Clear the siteb) Establish the building linec) Establish the non-bearing walld) Provide a ground-water drainage

2. Top soil is removed from a building site because it isa) A good practice to back-fill the areab) Necessary to dispose of water quicklyc) Unsuitable for building foundationsd) Difficult to do construction work in water

3. Which of the following factors influences house design?i. Availability of land for buildingii. The nature of the buildingiii. The closeness of services

a) I and II onlyb) I and III onlyc) II and III onlyd) I, II and III

4. The site drawing above shows the batter board labeleda) Ib) IIc) IIId) IV

5. The purpose of hoarding is to providea) office accommodationb) site securityc) stepped foundationsd) ground support

6. The drawing above shows the layout for the corner of a house. If the corner is square, then XY is

a) 15b) 20c) 25d) 30

Multiple choice answer

1. A2. C3. D4. D5. B6. A