Waterproofing products sort into four working families — acrylic, cementitious, polymer-modified and admixtures — and the right one follows from the surface, not the brand. Know what each family is good at and most product confusion resolves itself.
The four families
Acrylic coatings
Liquid-applied films that cure elastic. Their virtue is movement: they stretch over hairline cracking, which exposed roofs do constantly as they heat and cool. Natural home: roofs, terraces and exposed walls. Their limit: they want a dry surface to cure on and they are a film — surface preparation decides them (the roof sequence).
Cementitious coatings
Cement-based slurries that bond into concrete and cure rigid. Their virtue is bond and tolerance of damp substrates; their limit is rigidity — they do not bridge moving cracks. Natural home: water tanks, sumps, bathroom floors before tiling, basements.
Polymer-modified systems
Cement chemistry with polymer flexibility added — the middle path, and the workhorse of Indian construction. More movement than pure cementitious, more bond than pure acrylic. Natural home: bathrooms, balconies, terraces under protection, general building waterproofing.
Admixtures
Added into concrete or mortar while mixing, so the material itself resists water from the start. Their moment is construction; they are prevention, not cure, and no admixture in the slab excuses skipping surface protection on an exposed roof.
Shortlisting by surface
| Surface | First family to consider | Why |
|---|---|---|
| Exposed roof / terrace | Acrylic or polymer-modified | Thermal movement needs elasticity |
| Bathroom under tiles | Polymer-modified or cementitious | Bond under tile adhesive, damp-tolerant |
| Water tank interior | Cementitious | Bond, rigidity, immersion service |
| Basement walls | Cementitious / polymer-modified | Damp substrate, ground contact |
| New concrete work | Admixture + surface system | Resistance built in, protection on top |
The question that beats the chart
Chemistry narrows the field; the surface's own condition picks the product. Cracks, ponding, old coatings and damp history all shift the answer, which is why we ask for photographs before naming a product — send yours, and see what we supply for the roof-and-building case.
Frequently asked questions
Can acrylic go over old cementitious coating?
Over sound, clean, compatible coating, often yes — over failing coating, nothing works. The old layer's condition governs.
Is one family simply the strongest?
No. Each is strongest on its own ground and mediocre off it — a tank coated in roof acrylic and a roof done in tank slurry both fail, in opposite ways.