Contribute to Setting Out

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SETTING OUT

For measuring when setting out, builders may use a 30

metre setting out tape.

The tape measure can be either made of fabric or metal.

With constant use and pulling the tape tight a fabric tape

could tend to stretch which could give an incorrect reading.

Wipe all tapes clean after use and to maintain a metal tape,

lightly lubricate it with oil

 

SETTING OUT A 90 DEGREE ANGLE (SQUARE)

For ease of construction and to keep building costs to a

minimum the majority of buildings are made up of a collection of

squares and rectangles. Squares and rectangles all have

angles/corners at 90 degrees.

There are several ways to set out or check a right angle on site.  

BUILDERS SQUARE

 Never presume that the square is accurate. It may have been

made faulty or damaged through use or neglect.

To check a square for accuracy lay it on a flat surface and draw

round the 90 degree end. Totally reverse the square and place it on

the lines you have just drawn. If the square follows the lines, it is

accurate, if it shows different it is faulty.

3:4:5 METHOD

This method is also known as Pythagoras. A triangle having

sides measuring 3m, 4m & 5m, creates a perfect 90 degree

angle, at the corner. By using this method builders are able to

set out a square corner using just a tape measure.

A B

C

3m

5m

90 degrees

4m

SETTING OUT OTHER ANGLES

90 degree angles, and other angles, can also be set out using

optical equipment, such as a Site Square or a Theodolite.

Nowadays it is quite commonplace to use equipment

incorporating a laser beam and setting out buildings can now

be achieved with the use of satellite navigation.

SET OUT A 45° / 135° ANGLE(FROM POINT A)

 EQUIPMENT REQUIRED =

STRAIGHT-EDGE / BUILDERS SQUARECHALK OR PENCIL / TAPE MEASURE.  1.EXTEND WALL LINE XA TO B. 2.MEASURE ANY DISTANCE FROM A (600mm) TO FIND POINT B. 3.DRAW LINE BC AT 90° TO LINE XB (USE BUILDERS SQUARE OR 3:4:5 METHOD)  4.MEASURE FROM B TO C (600mm) – same distance as in Step 2. 5.JOIN POINTS A TO C. 6.LINE AC CREATES A 45° ANGLE WITH LINE BX & ALSO CREATES A 135° AT THE ANGLE AT CAX 

SETTING OUT OTHER ANGLES

C

135° 45°

AX

B

 

IN A SQUARE ALL THE ANGLES ARE 90°.BY DRAWING A LINE FROM CORNER TO CORNER THE ANGLES HAVE BEEN HALVED. 

SET OUT A 60° / 120° ANGLE (FROM POINT A)

EQUIPMENT REQUIRED =STRAIGHT-EDGE / CHALK OR PENCIL / TAPE MEASURE / TRAMMEL SET COMPASS OR LINE

STEP 1 

1. EXTEND LINE XA. 

USING A COMPASS SET AT ANY DISTANCE ((600mm) OR A PIECE OF LINE AND CHALK SCRIBE AN ARC TO CREATE POINT B.

STEP 1

1. EXTEND LINE XA.

USING A COMPASS SET AT ANY DISTANCE ((600mm) OR A PIECE OF LINE AND CHALK SCRIBE AN ARC TO CREATE POINT B.

X A

C

B

STEP 2 PLACE COMPASS POINT ON B, WITH COMPASS SET TO SAME DISTANCE, AND SCRIBE AN ARC, INTERSECTING THE PREVIOUS ARC TO CREATE POINT C

X BA

STEP 3 

DRAW A LINE FROM A TO C. THIS LINE CREATES A 60° & A 120° ANGLE TO THE BASE LINE  BY JOINING B TO C CREATES AN EQUILATERAL TRIANGLE. THIS SHAPE HAS ALL 3 ANGLES EQUAL TO 60° 

120° 60°

B A X

C

THE BUILDING LINEThis is an ‘imaginary’ line, determined by the Local Authority Highways Department. This line is usually a measurement taken back from a point on the highway – maybe the centre of the nearest road, the kerb line of the pavement, or a manhole in the roadway. Its’ function is for any possible future road widening; therefore to make sure that any new construction will be far enough back from the highway. Any infringement of this measurement could result in fines or legal proceedings to remove any construction in front of this set measurement. Contacting the Highways Dept. will position this line. Consider that if the construction faces more than one roadway, there could be more than one Building Line measurement required.

ROADWAY

KERB LINE

MEASURED BACK FROM KERB LINE

BUILDING LINE

No permanent part of the construction may overstep the Building Line. You may build up to the Building Line, behind it, but NOT INFRONT of it.

THE BUILDING LINE

SETTING OUT A RECTANGULAR BUILDING

Setting out is required to locate the position of a building on the

ground. The setting out determines the positions of the walls,

which in turn determine where the ground is to be excavated

and the concrete poured, to create the foundation trenches.

 

EQUIPMENT REQUIRED:-

DRAWING / 30M TAPE / 3M TAPE/ STEEL SETTING

OUT PINS / LUMP HAMMER

STEP 1 AFTER DETERMINING THE POSITION OF THE BUILDING LINE, SET OUT USING STEEL PINS AND BUILDING LINE TO POSITION THE FRONTAGE LINE (AB) OF THE NEW BUILDING STEP 2 DETERMINE ONE OF THE FRONT CORNERS (A) AND SET LINE (AC), SQUARE TO THE FRONTAGE LINE.

FRONTAGE LINE

C

A

B

D

STEP 3 MEASURE THE LENGTH OF THE BUILDING ( A – B) AND ESTABLISH POINT B. STEP 4 ERECT LINE BD, MAKING SURE THE ANGLE AT B IS 90 DEGREES.

C

A

CHECKING THE DIAGONALS

STEP 5 MEASURE THE WIDTH OF THE BUILDING, A-C & B-D. POSITION A LINE FROM THESE 2 POINTS TO COMPLETE THE RECTANGLE.

D C

B A

STEP 6 TAKE A MEASUREMENT FROM CORNER TO CORNER (A - D & B - C). WHATEVER A – D MEASURES THEN B – C MUST MEASURE THE SAME. IF BOTH DIMENSIONS ARE THE SAME THAT MEANS THAT EACH CORNER IS PERFECTLY SQUARE. IF DIMENSIONS DIFFER THEN THE SETTING OUT PROCESS MUST BE RE-CHECKED FOR FAULTS. STEP 7 AS A FINAL CHECK, RE-CHECK ALL THE DIMENSIONS FOR ACCURACY

D C

B A

The next process is to erect CORNER PROFILES, set back from each corner.

As shown above, timber pegs are driven into the ground and a timber profile board nailed across.

SETTING OUT LINE

PROFILE BOARD SIZE APPROX. 75mm x 30mm

TIMBER PEGS APPROX. 50mm x 50mm

STEEL SETTING OUT PIN

SETTING OUT LINE

CORNER PROFILES

Because the steel setting out pins will need to be removed for excavation

of the building, each timber corner profile, because it is set back, can

remain in position whilst the building foundations are removed/excavated.

 

The setting out lines are extended from the steel setting out pins and the

positions of each line marked onto the profile board. When the bricklayer

begins to set out the external walls he/she can attach the lines onto the

relevant marks, without the need for having to set out the building again.

 

THE POSITIONING OF SETTING OUT PROFILES FOR A TYPICAL BUILDING

The setting out profiles are set back from the building so that they will not get hit by machinery working on the excavation. If excavation was to be carried out by hand the profiles could be positioned closer to the works.

 When the foundation concrete has set the original setting out lines are fastened to the setting out profiles, once again. The bricklayer now needs to transfer the lines positions onto the concrete foundation.  This is achieved by carefully plumbing down where the lines travel and marking this onto the concrete. These marks represent the positions of the walls from above ground to below ground.

LINES PLUMBED DOWN AND POSITIONS MARKED ON TO THIN SMEAR OF MORTAR. BRICKWORK CAN THEN BE SET OUT, BELOW GROUND LEVEL, IN THE CORRECT POSITION.

LEVELLINGInitially all four corners of a building will have to be built up to the same level.

This is usually firstly achieved for the horizontal damp proof level, which is generally 150 mm, above

finished ground level.

All buildings have a levelling DATUM point. This datum would be shown on the working drawing and it

is quite often the ground floor finished floor level, shown as F.F.L. More often than not this level is

usually the same as the D.P.C. level.

 

 

To find the F.F.L. / D.P.C. level of a proposed new building it may be necessary to transfer a level from

a datum elsewhere, possibly a long way away. This would be one of the first tasks to be done on a

construction site and a surveyor would set up the SITE DATUM or TEMPORARY BENCH MARK.

 

site datum or temporary bench mark is a point

where all levels, either above ground, or below

ground are initially taken from. can be a length

of steel angle iron set firmly into the ground and

surrounded by concrete. to protect the datum

from damage, by plant, it would be positioned

away from activities and surrounded by a fence.

Symbol relating to a datum point

 For greater distances more accurate devices are required, such as :- 

DUMPY LEVELQUICK SET LEVELTILTING LEVEL (AUTOMATIC) THEODOLITE LASER LEVEL