ZIMSEC O Level · Building Technology and Design · Form 3, Form 4
Water supply
Pipes (PVC, copper, galvanised steel) bring cold water from the main or a tank; geysers or solar water heaters supply hot water. Stopcocks control the supply.
Drainage and sanitation
- Waste pipes from sinks and baths, and soil pipes from toilets, have traps (water seals) to stop smells.
- Drains slope towards a sewer or septic tank; inspection chambers allow cleaning.
- Ventilated improved pit (Blair) latrines are used in rural areas: the vent pipe with fly screen removes smells and traps flies.
Finishes
- Plastering: cement-sand plaster on walls, then painting.
- Floor finishes: tiles, polished screed.
- Ceilings: boards fixed to brandering.
- Paint: protects surfaces and improves appearance.
Estimating and costing
Measure quantities from plans and multiply by unit prices.
Worked example: A wall is 6 m long and 2.5 m high. About 50 bricks are needed per square metre of half-brick wall. How many bricks are needed?
Area = 6 × 2.5 = 15 m²
Bricks = 15 × 50 = 750 (add about 5% for breakages ≈ 790)
Exam tip: Always add an allowance for waste in estimates.
Check yourself
- Why do drains have traps?
- State the purpose of the vent pipe in a Blair toilet.
- A wall area is 20 m². How many bricks are needed at 50 per m², before waste?
Show answers
- The water seal stops bad smells (and gases) from entering the building.
- To remove smells and trap flies at the screen.
- 1 000 bricks
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