Housing Society Terrace Waterproofing — A Guide for Committees

A society terrace contract is one of the larger maintenance spends a committee approves, and it is unusually easy to get wrong — because the cheapest quotation is very often the smallest scope.

Start with a structural view, not a quotation

Before inviting bids, get the terrace inspected and documented: where the leaks are reported inside the building, where moisture actually shows on scanning, the condition of the existing layer, and the state of outlets and parapet junctions. That report becomes your tender scope.

Without it, every contractor scopes the job differently and the quotations are not comparable.

What the tender document should specify

• Exact system and brand, with the number of coats
• Dry film thickness in microns, or coverage per kg per sq ft
• Surface preparation: crack cutting and filling, removal of the failed layer, cleaning method
• Treatment of parapet junctions with a coving fillet
• Re-collaring of all pipe penetrations
• Outlet cleaning and re-detailing
• Curing time between coats
• Flood test before handover, with the committee present
• Warranty term and precisely what it covers

Comparing bids fairly

Put quotations side by side on the specification above, not on the total. A bid that is 30% lower and silent on preparation is not cheaper — it is a different, smaller job that will need redoing.

Ask each contractor for the material technical data sheet for the system they are proposing. A contractor who cannot produce one is not specifying a system, they are quoting a coating.

During the work

Nominate one committee member as the point of contact. Ask for the material bags or containers to be retained on site so consumption can be checked against the quoted coverage — this is the simplest possible protection against under-application, and it costs nothing.

The flood test is not optional

Insist that the terrace is flooded and held for the specified period before final payment, with committee members present. It is the only practical proof the system works, and it must happen before the final instalment is released, not after.

Warranty realities

A warranty is only as good as the entity behind it and the clarity of what it covers. Get the term, the covered area and the exclusions in writing on the agreement itself — not verbally, and not only on the quotation.