Topic 3 of 4 · Form 3
Floors and roofs
Roofs protect the building from weather and must be strong, waterproof and well drained.
Notes for this topic 1 file, in order
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Floors
- Solid ground floor: hardcore (compacted rubble), blinding (sand), damp-proof membrane, concrete slab, then screed and finish (tiles, polished cement).
- Suspended timber floors and reinforced concrete upper floors for multi-storey buildings.
Roofs
Roofs protect the building from weather and must be strong, waterproof and well drained.
- Flat roofs: concrete slab with waterproofing; slight fall for drainage.
- Pitched roofs: lean-to (mono-pitch), gable and hipped roofs.
Roof structure
Timber or steel trusses carry purlins, onto which roofing sheets or tiles are fixed. Wall plates spread the load onto walls. Roofs are tied down with hoop iron or wire to resist strong winds.
Roof coverings
Corrugated iron or IBR sheets (light, quick), concrete or clay tiles (durable, good insulation), and thatch (cool, cheap but a fire risk).
Gutters and downpipes
Collect rainwater and lead it away from foundations, or into tanks for harvesting.
Exam tip: Always mention tying roofs down – wind uplift damages many roofs in storms.
Check yourself
- List the layers of a solid ground floor from the bottom up.
- Name two types of pitched roof.
- Give one advantage and one disadvantage of thatch.
Show answers
- Hardcore, blinding, damp-proof membrane, concrete slab, screed/finish.
- Any two: lean-to, gable, hipped.
- Advantage: cool and cheap; disadvantage: fire risk/needs frequent maintenance.
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