Building Components: Foundations, Concrete Work and Stairs — CSEC Building Technology
This topic covers some of the main building elements: foundations, concrete work and stairs.
Foundations
The foundation spreads the load of the building safely onto the ground to prevent excessive settlement. Types:
- Strip foundation — a continuous strip of concrete under a load-bearing wall.
- Pad foundation — an isolated base under a single column.
- Raft foundation — a large slab under the whole building (for weak soils).
Foundation depth depends on the soil conditions and the load.
Concrete work
- Formwork (shuttering) moulds and supports wet concrete until it sets.
- Concrete is placed, compacted (to remove air) and then cured (kept moist) so the cement gains full strength.
- Reinforcement is added where tension occurs (e.g. in foundations, beams and slabs).
Stairs
Parts of a stair:
- Tread — the horizontal part you stand on.
- Riser — the vertical face between treads.
- Landing — a level resting platform between flights.
- String — the sloping member that supports the steps.
Stairs must have a comfortable, consistent tread and riser size for safe use.
Method (strip foundation)
- Excavate the trench.
- Place any reinforcement and formwork.
- Pour and compact the concrete.
- Cure the concrete before building on it.
Exam tips
- Foundations spread the load to the ground; know strip, pad and raft types.
- Formwork moulds concrete; curing develops strength.
- Stair parts: tread (horizontal), riser (vertical), landing, string.
- Know the order of casting a strip foundation.