Indian Standards for Waterproofing: A Practical Guide to IS 3067, IS 2645, IS 456 and IS 3370

Indian Standards are referenced constantly in waterproofing quotations and rarely read. This guide sets out what the four most relevant codes actually cover, so that a reference to them in a specification means something specific rather than serving as decoration.

The four codes that matter

IS 3067: the execution code

This is the code that speaks to how waterproofing is laid rather than what it is made of. Its value in a specification is that it establishes a benchmark for the detailing that determines whether waterproofing succeeds — junctions, upstands, treatment at penetrations, and the drainage arrangements that keep water moving off the surface.

Because it is a code of practice, it does not tell you which product to use. What it gives a client is a reference point: a specification stating that work shall comply with the relevant provisions of IS 3067 creates an obligation about the standard of detailing, which is precisely the area where cheap work cuts corners.

IS 2645: what it does and does not cover

IS 2645 is a product specification for integral waterproofing compounds — the liquids and powders dosed into concrete, mortar and plaster to reduce their permeability. It sets requirements and test methods for those admixtures.

Its limitation is the more important point. The code covers the admixture. It has nothing to say about membranes, waterstops, joint treatment or detailing. A quotation that offers “IS 2645 compliant waterproofing” for a basement is describing one component of a system and calling it the system. The right response is to ask what is happening at the construction joints, what membrane or coating is being applied, and how penetrations are being detailed.

IS 456: the substrate you are waterproofing

IS 456 governs plain and reinforced concrete generally, and three of its concerns bear directly on waterproofing outcomes: durability requirements for different exposure conditions, minimum cover to reinforcement, and permissible crack widths.

Cover matters because inadequate cover is the underlying cause of most reinforcement corrosion, and corroding steel spalls concrete off from behind — taking any waterproofing with it. Where a survey finds spalling with exposed rusted bars, that is an IS 456 issue before it is a waterproofing issue, and it dictates the sequence: repair the concrete to sound condition, treat the steel, reinstate the section, and only then waterproof.

IS 3370: liquid-retaining structures

For water tanks, reservoirs, sumps and treatment structures, IS 3370 is the governing code. It is a design code for structures that must retain liquid, which brings it into direct contact with waterproofing decisions: crack width control, joint arrangements, and the testing regime for a completed structure.

The practical implication for a client is the acceptance test. A liquid-retaining structure is proven by filling it and holding the level, and if a tank waterproofing quotation does not include a hold test of 48 to 72 hours with the result recorded, it is omitting the only objective evidence that the work succeeded.

How to reference standards usefully

Three practices make code references meaningful rather than ornamental:

• Reference the code and the requirement. “Detailing at upstands and penetrations shall comply with the relevant provisions of IS 3067” is enforceable. “IS compliant” is not.
• Ask which code applies to which element. A tender covering a terrace, a tank and a basement engages different codes for each, and a bid that cites one code for the whole scope has not thought about it.
• Ask for the product data sheets. Standards compliance for materials is demonstrated on the manufacturer’s documentation, not by assertion in a quotation.

None of this requires engineering knowledge. It requires asking which standard applies to which part of the work, and noticing whether the answer is specific.

Frequently asked questions

Which IS code applies to roof waterproofing?

IS 3067, the code of practice for waterproofing of buildings — covering execution and detailing rather than products.

What does IS 2645 cover?

Integral waterproofing compounds for cement mortar and concrete. Only the admixture, not the wider system.

Are IS codes mandatory?

Voluntary unless made contractual or required by bye-law. Referencing them in a tender is what gives them force on a private project.