Once you get hold of the approved architectural drawings, the next step is setting out the house on the construction site. To nail the problem for good, pay close attention to details in order arrive at the correct house position and orientation .Miss the bull’s-eye and what follows will be a house facing in the wrong direction , a house with walls out of alignment, a structurally weak building or a drainage nightmare.Ultimately you will be forced to shell out more money to correct the mess ,when it could have been avoided by care and foresight.
To set out a house you will need the following tools.
- Building plans
- Try Squares
- Two Tapes measure(20 metres)
- Profile poles/timber
- Setting strings
- Timber pegs(50mm square softwood with pointed end)
- Coloured spray/chalk /cement powder.
To keep the ball rolling, keep in mind that the position of the foundation is determined by external walls and internal load-bearing walls .Fire the first shot at decent housing problem by:
- Clearing the site of vegetation and top soil
- Establish the baseline which ideally should be the plot boundary. Give margin of at least one meter between the plot boundary and the external wall of the building.
- Set out the position of external corners of the front wall. Start with point adjacent to the plot boundary and measure out the width of building and mark out the two end points. Then knock down into these marked point the peg A and then peg B.
- Establish the third corner. Using two tapes, measure out the diagonal and straight side of the proposed building. Where the two points meet, mark it out and knock down upon the point the third peg C. Use the Try square to confirm the corner angle is 90◦.Also use the Pythagoras theorem to to confirm the dimensions of the diagonal are accurate, where (c) is the diagonal and (a) and( b ) the other two sides of the proposed foundation trenches.
- Establish the fourth corner by using same diagonal measurements and two tapes. Mark out the corner by fixing a peg on the spot D.
- Confirm the corners have 90◦angle and the diagonal are equal using the Try square and tape measure.
- Erect profile poles/timber to physically mark the outline of the building. The poles should be close enough to the proposed building lines to facilitate easy reach and use. A suitable distance is 0.6metres to 1 metre from the proposed foundation trenches.
- String the lines. Using nylon lines ,string the first line from one profile pole over the centre of the pegs in the row and onto the opposite profile pole. Repeat the procedure for every row. These lines marks the external face of the wall.
- Establish inner and outer edges of the foundation. Every profile pole is adjacent to the external wall. From this point measure an appropriate length (K) from the face of the proposed wall to the outer edges of the foundation. From the outer edge measure the width of the foundation and mark the inner edges on the profile pole. Repeat the procedure for all profile poles, checking the dimensions for their accuracy.
- Mark out the foundation lines using chalk, cement powder or aerosol paint marker. Using the outer lines as guides mark out the lines on the surface of the ground. When all the lines have been marked on the ground, physically marked the lines using a Hoe/Jembes by lightly digging along the lines. And then remove the strings by winding them up on a peg, taking care to leave profile poles in position for later use by masons.
- Excavate the trench-This should follow the Jembes marked out lines. Foundation excavation is done either manually or mechanically.
- Establish the level. Measure the foundation trenches depth and ensure they are level and of the same height. If the foundation trenches are not level, then a split course is necessary, which may waste funds and time. To ensure the foundation is level, either use a number of softwood staves fixed into the center of the trench with their tops at correct level or use a number of pegs fixed into the trench wall marking the correct level for the for the concrete.
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