Setting out a residential house

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:

  1. Clearing the site   of  vegetation and   top  soil
  2. 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.
  3. 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.
  1. 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.
  2. Establish the fourth corner by using same diagonal measurements and two tapes. Mark out the corner by fixing a peg on the spot D.
  3. Confirm the corners   have 90◦angle   and the diagonal are equal using the Try square and tape measure.
  4. 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.
  5. 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.
  1. 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.
  1. 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.
  1. Excavate the trench-This should follow the Jembes  marked out lines. Foundation excavation is done either manually or mechanically.
  1. 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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