It's common to receive waterproofing quotes that read almost identically — a product name, an area in square metres, a total price — and assume the choice comes down to whichever number is lowest. In practice, the price per square metre is one of the least informative numbers on the page, because it says nothing about substrate preparation, joint detailing, or which of the several systems covered in this hub is actually being proposed.

A properly scoped quote should specify the exact system (cementitious, liquid-applied polyurethane, bituminous sheet, or a hybrid combination), the number of coats or layers, how joints, corners, and penetrations will be detailed — this is where most real-world failures start, not in the middle of a flat surface — and what surface preparation is included, since a membrane applied over an unprepared, damp, or poorly cleaned substrate is very unlikely to perform to its rated life regardless of product quality.

It's worth asking directly whether the quoted system suits the actual water exposure the structure will face: hydrostatic pressure below ground calls for a different specification than damp resistance above ground, as covered separately in this hub, and a quote that doesn't distinguish between the two is a warning sign rather than a simplification.

Warranty terms are the other detail worth reading closely — what's covered, for how long, and whether it covers materials only or materials and workmanship together. A lower price paired with a shorter or narrower warranty usually reflects a real difference in confidence about how the job will hold up, not just a discount.