Under-reamed piles: bulb formed at the designed depth
Applies only if your house has an under-reamed pile foundation.
Why — act while you have leverage
Under-reamed piles — piles with a widened bulb at the bottom are the standard answer to black-cotton and expansive soils across much of India. Their whole capacity is in the bulb — a pile bored without one is a plain pile pretending.
What to look at
- Spoil volume increasing as each bulb is cut
- Bulb depth logged per pile
- The number of bulbs matching the drawing
How to check it yourself
The under-reaming tool is run at the designed depth and the operator confirms the bulb has formed. Spoil volume rises noticeably when a bulb is cut — watch for it. Number and spacing of bulbs follow the design, not the driller's habit.
Where this comes from: IS 2911 (Part 3):1980 — Under-reamed piles (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
- Plinth beam continuous and tied into the foundation
- Column starter bars plumb, with 40 mm cover and correct laps
- Backfill compacted in layers, not tipped in
- Damp proof course laid unbroken at plinth level