Roofs and terraces cause most of the water problems in Indian buildings, and they are the surfaces where waterproofing is most often done badly. This guide covers both — they are different jobs — from finding the cause to testing the finished work.
Roof or terrace?
A roof is a slab that sheds water and is rarely walked on. A terrace is a roof people use: tiled or bare, walked on, washed, furnished, draining at corners, meeting a parapet. The distinction changes the method, which is why they have separate guides — roofs, start to finish and terraces, start to finish — and separate service pages: roof, terrace.
1. Why it is leaking
Eight causes: thermal cracking, the parapet junction, failed old coating, ponding, blocked drains, construction joints, penetrations, and water arriving from elsewhere. Find yours before buying anything — the drip below rarely sits under the entry above.
2. Repairing what you find
- Crack repair — cut, clean, fill, seal. Filling "as found" is why repairs fail.
- Why leaks come back — and what a lasting repair actually consists of.
- Parapet junctions — coving, upstand and coping. The edge where most "treated" terraces still leak.
- Drainage: if water stands, falls are corrected before any coating. No chemistry cures a puddle.
3. Choosing the system
Five questions your roof answers — does the slab move, is it walked on, does water stand, what is on it now, how hot does it run. Then the chemistry families in acrylic vs cementitious vs polymer, and the forms in liquid vs membrane.
If what you have been offered is a tin of "roof paint", check what it actually is first: roof paint, roof coating and roof waterproofing are three different things and only one of them stops a leak.
4. Timing
This is dry-season work with a monsoon deadline — why, and what to inspect now. In the north plains the window is generous: October to March. The annual habit is the pre-monsoon checklist.
5. Doing it right
Ten mistakes that cause callbacks. The short version for roofs: dry surface, real preparation, details and junctions treated individually, full cure, and a water test before anyone declares success.
Tiled terraces work differently — the waterproofing sits under the screed, not under the tiles, and the layer order decides everything: what goes where under terrace tiles.
6. What it costs
Six cost drivers — surface condition, drainage correction, detailing quantity, system chosen, access and scale, and whether a test is included. Comparing bids on scope rather than rate is the whole skill.
Frequently asked questions
Can I waterproof a roof myself?
A sound, simple slab with no active leak — yes, carefully. An already-leaking roof or one with standing water deserves experienced hands.
How often should a roof be redone?
Every system has a service life, and no honest supplier states one number for all roofs. Inspect yearly; act on findings rather than on a calendar.
What do you need from me to advise?
Photographs of the roof surface, any cracks, the drains, and the damp inside — plus your city. That is usually enough for a first opinion via the roof page.