Column starter bars plumb, with 40 mm cover and correct laps
Columns start in the foundation. Starter bars — the steel left sticking up out of the foundation for the column that are out of plumb or short on lap are corrected by bending them into place — which is the crack you see at the first-floor slab five years later.
What to look at
- Plumb checked on two faces, before and after the pour
- Cover blocks on all four faces of the column cage
- Laps staggered between adjacent bars rather than aligned
How to check it yourself
Check starters plumb in both directions before the pour and again after. Cover to a column is not less than 40 mm under IS 456 cl. 26.4.2.1 — more in severe coastal exposure. Laps are the greater of 24d or 0.8Ld in compression and are staggered, not all made at the same level.
Where this comes from: IS 456:2000 cl. 26.4.2.1 (columns — nominal cover not less than 40 mm); cl. 26.2.5 (compression lap, the greater of 24 times the bar diameter or 0.8 times the development length) (indian standard or building code)
More foundation checks
- Photograph before this is covered
- Cover blocks in place — 50 mm to footing reinforcement
- Steel matches the grade and diameter on the drawing
- Concrete cured for at least seven days
- Rubble foundation: through bond stones at every course band
- Rubble foundation: hearting solid, chips under a fifth of the volume
- RCC footing: size and depth as designed, on the correct stratum
- Raft foundation: reinforcement laid in the order the drawing gives and not walked flat
- Pile foundation: pile records kept for every pile, not a sample
- Under-reamed piles: bulb formed at the designed depth
- Plinth beam continuous and tied into the foundation
- Backfill compacted in layers, not tipped in
- Damp proof course laid unbroken at plinth level