Waterproofing and painting checks in Kerala
A finish coat is only as good as what is under it. Preparation is what this stage hides.
The checks at this stage (7)
- Photograph before this is covered
What disappears at this stage: which waterproofing system your roof actually got, once the finish coat is on. 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.
- Ponding test passed before the waterproofing is covered
Waterproofing is the one layer whose failure is certain to be discovered and certain to be expensive. Once tiles or screed (the levelling layer under a floor finish) go over it, testing means removing them.
- Painting held until the surface is dry enough to take it
Paint applied over damp plaster or in monsoon humidity blisters and peels. The failure is blamed on the paint and paid for by the homeowner.
- Paint thinned only as much as the tin allows
This is the easiest money on your site to take. Paint thinned past what the tin allows spreads further, bills the same, and fails as patchy chalky walls two years later — by which time everybody blames the weather.
- Primer used, and the coats applied in the maker's order
Primer is the coat nobody sees and the one that decides whether the paint stays on. Skipping it saves a day and costs the whole finish.
- Putty kept thin — it is a filler, not a levelling layer
Thick putty is used to hide a wall the plasterer left uneven. It cracks and comes away in sheets, taking the paint with it, and the repair means stripping back to plaster.
- Walls checked for damp and for alkali before the first coat
New plaster is chemically alkaline and full of water. Paint applied over either lifts, blisters or discolours — and it will be your paint bill that is questioned, not the schedule that caused it.
What good work looks like
Three roof systems, one non-negotiable order
Coating systems brush or roll on over prepared concrete. Membrane systems torch or stick down, overlaps facing the water flow, over the same preparation. Whichever system: preparation first, primer where the system asks, and a flood test before anything covers it.
- Surface prepared and primed before the system goes on
- Overlaps lapped the right way, facing the run-off
- A flood test held and photographed before covering
- Membrane laid on a damp, dusty deck
- Skimpy overlaps that open with the first summer
- No protective screed - later work punctures it
IS 3067:1988 · IS 1346:1991 · IS 2645
An admixture is not a waterproofing system
Waterproofing compound mixed into concrete reduces how much water soaks in. It is a helper, not a roof system. On a Kerala flat roof, relying on the admixture alone is the cheapest option on the quote and the most expensive one on the ceiling.
- A dedicated membrane or coating over the slab
- The admixture used with a system, not instead of one
- The chosen system named in writing with its warranty
- A flat roof with only admixture in the concrete
- The quote line just says waterproofing, no system named
- No warranty because there is no system to warrant
IS 2645 - a compound spec, not a roof system
New plaster waits about a month for paint
Fresh plaster is wet and alkaline inside long after it looks dry. Paint it early and the alkali attacks the paint from behind - peeling and blistering that no warranty covers. About 28 days, then an alkali-resistant primer, then the coats.
- Plaster age confirmed from the dated record
- Alkali-resistant primer on, product in the photo
- Coats counted from dated photos, not memory
- Painting green plaster to hit a function date
- Skipping primer as an economy
- Coats claimed at billing with nothing to show
IS 2395 Parts 1 and 2:1994
Read the waterproofing warranty before anyone drills
System warranties run for years - and carry void conditions: wrong application, missing protection screed, later punctures. The follow-on trades are the usual killers. Get the warranty in writing and read what voids it before the next worker arrives on the roof.
- A written system warranty with the applicator's sign-off
- Void conditions read before follow-on work starts
- The protection screed actually installed
- A verbal warranty from the applicator
- AC and solar fitters drilling the membrane later
- The screed skipped to save one line on the bill
Manufacturer document - the named brand's own
Red flags and money traps
Waterproofing compound mixed into concrete is a helper, never the system. On a Kerala flat roof, the quote's cheapest waterproofing line is the one your ceiling pays for later. A real system has a name and a warranty.
Ask: Which system - coating or membrane - and where is its written warranty?
The difference between one coat and two is invisible on day one and very visible at billing. A dated photo as each coat goes on, and the empty containers kept, settle the count without an argument.
Keep: Dated per-coat photos and the empty cans - batch numbers included.
Every product has a stated dilution limit. Beyond it, coverage and washability quietly leave the wall. If the mixing bucket looks mostly like water, photograph it and ask for the datasheet figure.
The limit: The named manufacturer's dilution figure - not the painter's habit.
Manufacturers publish a maximum surface moisture and a minimum drying interval between coats. In the Kerala monsoon these are routinely ignored because the schedule is tight. Ask for the product data sheet and hold the coat.
Trade practice, not a code: Paint manufacturer application data sheets; established practice — no single IS clause fixes a site moisture limit for decorative painting
Putty fills hairline imperfections in a plastered wall. It is not there to straighten a wall that is out of true — that is a plastering problem and should go back to the plasterer. Run a straight edge over the wall before puttying starts; if the gap is more than a millimetre or two, the wall needs correcting, not filling.
Trade practice, not a code: Manufacturer application data sheets; established practice — putty thickness is not fixed by an IS clause