How to Read a Waterproofing Quotation: An 18-Point Audit Checklist

Most people comparing waterproofing quotations compare the totals. That is the one comparison that cannot be made reliably, because the totals describe different amounts of work. This checklist sets out the eighteen items a quotation should state, grouped by what each omission tends to cost.

Part one: the specification (points 1–6)

These six establish what is actually being applied. Without them, no comparison between two quotations means anything.

Point five is worth a moment. Multiply the stated coverage rate by the area and compare it to the total material quantity in the quotation. If the arithmetic does not work, the job cannot be delivered as written, and it is far better to establish that at quotation stage than at the second coat.

Part two: preparation and detailing (points 7–12)

• 7. Removal of existing layers. Is the failed coating being stripped, and by what method? A new system bonded to a delaminating old one fails with it.
• 8. Crack treatment. Are cracks being cut open, filled and reinforced, or coated over? Coating over a crack is not a repair.
• 9. Junction and upstand detail. How is the parapet junction treated, and to what height does the system turn up? Below 150 mm on a terrace is inadequate.
• 10. Penetrations. Are pipe collars and drain seals included by name? These are where most leaks originate.
• 11. Falls and outlets. Are ponding areas being corrected, and are the rainwater outlets being cleared and re-set below finished level?
• 12. Curing intervals. What time is allowed between coats, and does the programme actually accommodate it? Compressed curing is the most common programme-driven failure.

Points 9, 10 and 11 deserve emphasis because they describe where waterproofing fails in practice. Membranes and coatings rarely fail in the middle of a surface. They fail at the parapet, at the pipe, and wherever water was allowed to stand.

Part three: verification and commercial terms (points 13–18)

• 13. Water testing. Is a flood or ponding test included before handover, and is the result recorded? For a tank, is a 48–72 hour hold test included?
• 14. Thickness verification. Will dry film thickness be checked with a gauge, and are readings recorded?
• 15. Warranty term. Stated in years, in writing.
• 16. Warranty exclusions. Stated explicitly. A warranty with no listed exclusions has undisclosed ones.
• 17. Inclusions. Debris removal, scaffolding, water for curing, electricity, and making good tiles or plaster removed during the work.
• 18. Variation mechanism. What happens if more damage is found once the surface is opened up, and at what rate is additional work charged?

Point 18 is the one experienced clients insist on. Waterproofing frequently uncovers more than the inspection could see, and the difference between a professional contractor and a difficult one is whether that eventuality was priced and agreed in advance or becomes a negotiation halfway through.

Reading between the lines

Three patterns are worth recognising. A quotation that prices by area alone with no specification is a placeholder, not an offer. A quotation substantially below the market range for the named system is almost always short on preparation, coats or thickness, and the gap will appear later as a variation or as an early failure. And a quotation that includes a written warranty but declines to state its exclusions has exclusions it would rather you discovered after the money has moved.

None of this requires technical expertise to check. It requires asking for eighteen items in writing, and noticing which contractor is comfortable providing them.

Frequently asked questions

What should a waterproofing quotation include?

The system and brand, coat count, dry film thickness or coverage rate, preparation scope, crack and junction detailing, curing intervals, water testing, warranty term and exclusions, and who pays for debris, scaffolding, water and making good.

Should I accept a verbal warranty?

No. Ask for the wording before approving the estimate. A contractor unwilling to write the terms down at that stage is giving you information.

What is dry film thickness and why does it matter?

It is the cured thickness of the coating in microns, and it determines performance. The same product at half the specified thickness costs half as much in material and fails far sooner, and the difference is invisible once dry.