Setting out is the step where the house on your drawings is marked on the real ground before digging starts. A surveyor or engineer finds the plot beacons, marks the building lines and setbacks your permit requires, then sets up timber profiles and string lines showing the exact position of every wall and column. Done carefully, it takes one to two days and costs little. Done wrong, it can put your house over a boundary, inside a road reserve, or out of square, and those mistakes are expensive or impossible to fix later.
Why does setting out matter so much?
Everything that follows is built on it. If the corners are in the wrong place, the foundation, walls, roof and even the septic tank and drains will be in the wrong place too. Common problems we are called to sort out include:
- A boundary wall or house built partly on the neighbour's land.
- A house too close to the road, breaking the building line on the permit.
- Rooms that are not square, so tiles, ceilings and kitchen units never fit properly.
- A floor level set too low, so water runs into the house in heavy rain.
What are beacons, building lines and setbacks?
| Term | What it means |
|---|---|
| Beacons | Survey markers (usually concrete pillars with a pin) at the corners of a surveyed plot, shown on the survey plan |
| Plot boundary | The legal edge of your land, running between the beacons |
| Building line | The line nearest the road that the front of the building must not cross |
| Setbacks | Minimum distances from the building to the side and rear boundaries |
| Road reserve | Land kept for current or future road widening, where you cannot build |
| Plot coverage | The share of the plot the building is allowed to cover |
Setbacks and coverage are set by the planning rules for your area and shown or referred to on your approved drawings and permit. They differ between councils and between residential, commercial and mixed-use zones, so always use the figures on your own approval. See our guide to the building permit process.
How is a house set out step by step?
- Confirm the beacons. A licensed land surveyor finds the beacons from the survey plan. If any are missing or disturbed, have them re-established officially before you build. See how to check a land title.
- Mark the building line and setbacks from the boundaries using a tape or a total station.
- Fix a baseline. Usually the front wall of the house, measured from the building line.
- Set right angles. Use the 3-4-5 method (a triangle with sides of 3 m, 4 m and 5 m gives a perfect right angle) or an instrument.
- Check the diagonals. In any rectangle, the two diagonals must be equal. If they differ by more than about 10 mm, adjust before going further.
- Build profiles. Timber boards fixed on pegs about a metre outside the building, with nails marking the wall centres and foundation edges. Strings stretched between them show where to dig.
- Set the levels. Establish a datum (a fixed reference height) and set the finished floor level, usually at least 150 to 300 mm above the surrounding ground, higher on flood-prone sites.
- Check again before concrete. Measure the trenches and the steel against the profiles before every foundation pour.
How do I choose the floor level?
The floor level decides whether rainwater flows away from your house or into it. Look at the road level, the neighbours' levels and where water flows during heavy rain. On low or flat sites, especially in parts of Dar es Salaam, raising the floor and the plinth is one of the cheapest ways to protect the house. See how to protect your building from flooding.
Who should do the setting out?
For the plot boundaries and beacons, a licensed land surveyor. For the building itself, your contractor's engineer or site surveyor, using the approved architectural and structural drawings. For simple single-storey houses, an experienced foreman can set out from the surveyor's marks, but the engineer should still check it. Setting out usually costs a small part of the total budget: a beacon survey might cost a few hundred thousand shillings, and the building setting out is normally included in the contractor's price. Fees vary by location and plot size.
Frequently asked questions
What happens if my house crosses the building line?
The council can refuse occupation, issue a stop order or require demolition of the part that crosses. It also causes problems when you sell or use the house as security for a loan.
Can I build right up to my boundary?
Usually not on the sides and rear of a residential plot. Check the setbacks on your approved drawings. Boundary walls are treated differently from buildings.
What if a beacon is missing?
Do not guess its position. Hire a licensed surveyor to re-establish it from the official survey records before you build anything near the boundary.
How accurate should setting out be?
For a house, corners should be within a few millimetres and diagonals within about 10 mm. Modern instruments make this easy.
Start your build in the right place
Vika Construction sets out every building with engineers and checks it before each pour. Contact us to plan your project.
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