Foundation checks in Kerala
Steel, cover blocks and termite treatment disappear the moment concrete is poured. Look, photograph, then pour.
The checks at this stage (14)
- Photograph before this is covered
What disappears at this stage: the steel, cover blocks and termite treatment, once concrete is poured. It cannot be inspected again without breaking something, so the photos taken now are the only record that will ever exist. Skipping this stays on your handover record permanently.
- Cover blocks in place — 50 mm to footing reinforcement
Cover is the only thing between your steel and the water in the ground. Too little and the bars rust, swell and split the concrete from inside; you will not see it for years and cannot fix it when you do.
- Steel matches the grade and diameter on the drawing
Substituting a smaller diameter or a lower grade is invisible once concrete covers it, saves the contractor real money, and is exactly the swap a homeowner cannot detect later.
- Concrete cured for at least seven days
Concrete gains its strength from water, not from time. A footing that dried out in its first week is permanently weaker than the number on the design, and no later curing recovers it.
- Rubble foundation: through bond stones at every course band
A rubble wall without through stones is two thin walls leaning on each other. It stands until the ground moves, then splits down the middle — and nothing about the finished plinth shows whether they were laid.
- Rubble foundation: hearting solid, chips under a fifth of the volume
Filling the middle of a rubble wall with chips instead of stone is the cheapest way to build it and the hardest to see. The wall settles unevenly for years afterwards.
- RCC footing: size and depth as designed, on the correct stratum
A footing cast smaller than designed, or founded higher than designed, carries less than the building asks of it. Both are invisible the moment backfill goes in.
- Raft foundation: reinforcement laid in the order the drawing gives and not walked flat
A raft carries the whole house on one slab. Its top steel matters as much as its bottom, and top steel trodden down during the pour is a raft that behaves like a thinner one.
- Pile foundation: pile records kept for every pile, not a sample
On filled or backwater land the piles are the building. A short or defective pile is undetectable afterwards, and the record made on the day is the only evidence that ever exists.
- Under-reamed piles: bulb formed at the designed depth
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.
- Plinth beam continuous and tied into the foundation
The plinth beam (the concrete band the walls start from) is what stops the walls above from moving independently of the foundation below. Broken at a doorway or cast without laps into the columns, it is a decorative band of concrete.
- 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.
- Backfill compacted in layers, not tipped in
Loose backfill settles. The floor over it sinks, the plinth cracks, and the fix is to break out the floor you have just paid to finish.
- Damp proof course laid unbroken at plinth level
The DPC is the layer that stops ground water climbing your walls. Broken at one doorway, it lets damp into the whole run — and the stain appears on a painted wall a year after you moved in.
What good work looks like
Anti-termite treatment, done before covering
A chemical barrier is applied to every soil surface that will later be covered - trench bottoms and sides, plinth fill, the wall edge - before the covering goes down. Done after concrete is laid, it is useless. Never sprayed in rain or on waterlogged soil.
- A dated record naming chemical, strength and litres used
- Treatment done immediately before concrete or fill goes over it
- The outer wall edge and wall-floor line included
- Spraying during rain or onto wet soil
- The treated barrier dug up by later work
- Treatment done after the base concrete - too late to matter
IS 6313 Part 2:2022
Cover blocks - the small blocks that save your steel
Small blocks hold the steel away from the shuttering so concrete wraps it fully - that concrete skin is what stops rust. Near the coast the required cover is thicker and the concrete grade higher than inland. Measure to the outermost steel, the stirrup.
- Blocks of the right thickness, closely spaced on all faces
- Steel nowhere resting directly on the shuttering
- Thicker cover used near the coast, not the inland habit
- Blocks missing or too few, steel sagging onto the form
- Cover measured to the main bar instead of the stirrup
- Thin inland-style cover used on a coastal site
IS 456:2000 Cl. 26.4, Tables 16 and 5
Where one pour ends and the next begins
Planned joints go at low-stress points shown on the drawing. Before the next pour, the old surface is roughened, cleaned of the weak top skin, and wetted - so the new concrete grips instead of just leaning on it.
- Joint positions planned, not wherever the mixer stopped
- Old surface hacked rough, cleaned and wetted before the pour
- Pour sequence discussed before pour day
- Random cold joints where work simply halted
- New concrete poured on the smooth, dusty old surface
- Joints landing at the most heavily loaded spots
IS 456:2000 Cl. 13.4 and Cl. 11
Red flags and money traps
Treatment sprayed onto wet or waterlogged soil is treatment wasted - the code itself forbids it. A crew that treats in drizzle to keep the schedule has spent your money on nothing.
If raining: The treatment waits. A day lost here is cheaper than termites in year five.
Anything wrong beneath a pour - missing blocks, short laps, missed treatment - converts from a ten-minute fix into breaking hardened concrete. The pour is the point of no return; treat pour morning as inspection morning.
Rule: No pour starts until your checks and photos are done. Ever.