Process of setting out a Building.
1.Students will first identify the site plan which shows the building footprint. Before the work begins, the students need to be able to identify that the architectural plans are stamped by the County Government for approval. This is because if the drawings are not approved, it’s the masons working on the site who are usually picked up and locked in police cells for working on a building that has not been approved as in the case of Kenyan building bye laws.
2.After this identification, the students can then read out the building footprint in relation to the plot boundaries.
In the drawing above, the left side of the building is at exactly the edge of the plot boundary. The top and bottom part are offset from the land plot boundary.
The markings using nylon strings will mark out the foot print as shown in the picture above.
- Using a nylon string, students can measure out the dimensions as shown on the architectural drawing then direct the string on one side to mark the building extents, offsetting and starting to measure from one end of the boundary wall.
- The other perpendicular building footprint extents are then pulled out and measured from the initial long section string to mark the footprint extent.
5.Using white lime powder, the building footprint is marked and is now ready for excavation.
For small sized buildings, manual labour is used to excavate.
For larger buildings, use of excavator machinery is more appropriate.
Once the top soil is excavated until stable ground or rock, a more detailed setting out of the internal wall partitions of the buildings can commence.
Once the top soil is excavated until stable ground or rock, a wooden formwork , made out of pine timber, is erected at the edges of the excavation. This forms the support of the nylon strings that are used to measure out the more detailed setting out for the interior walls.
Procedure for setting out.
1.Erection of Sawn timber formwork for foundation.
Once the soil is excavated till stable ground or rock, a 2inch by 2 inch cypress or pine timber post of around 3 feet is driven into the ground on one end of the corner of foundation at ground level.
2.Other pieces are driven into the ground in a spacing of approximately 4 feet apart until the extreme end of the foundation.
- A 4 inch by 1 inch cypress or pine timber plank is used to horizontally join all the 2inch by 2 inch posts till the farthest end.
- This is repeated for all extreme edges of the foundation.
This 4inch by 1inch timber plank is what will be later used to support nylon strings that will be dimensioned as per the architectural drawing internal wall.
- Once the timber formwork is erected around the foundation edges at the ground floor on all sides, the actual setting out where drawings are read from the architectural plan and interpreted and marked using nylon strings on the timber formwork can begin.
- See internal walls in the picture above. In some buildings, there will also be columns such as in the picture above, which will also be marked in the same manner.
- After this marking, excavation of the internal walls and column footings is the next step.
Francis Gichuhi kamau