Building Construction Techniques and Components
This domain checks that you can name each building component, state its function, and quote one dimensional rule a site inspection would verify. Questions typically show a component description and ask for its name, or give a floor height and ask for stair geometry.
Components from bottom to top
- Foundation: transfers load to soil; shallow forms include isolated and raft footings, deep forms include piles.
- Plinth: the built-up portion between ground level and floor level; plinth level is the datum for the DPC.
- DPC: a continuous 20 mm cement mortar 1:2 layer with waterproofing compound at plinth level, lapped at junctions and never broken for door thresholds without a sill.
- Bonds: English bond alternates full header and stretcher courses and is the strongest; Flemish bond alternates header and stretcher within one course; a queen closer sits next to the quoin header.
- Lintel: spans an opening with 150–200 mm bearing each side; the chajja above it throws rainwater clear of the wall.
- Load path in framed construction: slab to beam to column to footing.
- Staircase: rise 150–190 mm, tread 250–300 mm, and 2R + T between 600 and 640 mm.
Worked example
Floor height 3.2 m, chosen rise 160 mm, gives 3.2 ÷ 0.16 = 20 risers. Using 2R + T = 620, tread = 620 − 320 = 300 mm. A single flight of 19 treads would run 5.7 m, too long, so use two flights of 9 treads each (2.7 m per flight) with a 1.2 m mid-landing: overall going 2.7 + 1.2 + 2.7 = 6.6 m.
Traps that cost marks
Treating risers and treads as equal in number; forgetting the DPC or allowing it to be interrupted under a door; placing a header at the quoin without the queen closer; measuring stair length including the landing as if it were a tread; confusing a lintel with a beam.