Everyone asks for a price per square metre; almost nobody gets a comparable one — because two waterproofing quotes rarely describe the same system. Instead of quoting a number that would be stale in a month, here is what actually moves the cost, so you can compare offers like a professional.
The six cost drivers
- Membrane grade and thickness — a 5 mm mineral-finished InsuUltra carries far more polymer-modified compound than a 3 mm underlayer; thickness is the biggest single material variable. (Thickness guide here.)
- One layer or two — premium roofs use a 3 mm base + 4 mm cap. Nearly double the material — and a substantially longer service life.
- Carrier and polymer — polyester carriers and SBS elastomeric grades (InsuPrene) cost more than fiberglass and standard APP — and earn it in demanding applications.
- Surface preparation — screeds to falls, crack repair and priming (Insucoat) are often invisible in cheap quotes and then billed as extras.
- Detailing density — a clean rectangular roof installs fast; one crowded with units, penetrations and upstands takes skilled hours. Details, not field area, consume the labour.
- Protection and accessories — below grade, protection boards before backfill; on roofs, termination profiles and sealants.
How to compare quotes fairly
Require every offer to state: product name and manufacturer, polymer type, carrier, thickness, number of layers, lap widths, primer, and what preparation and detailing are included. If a quote can’t name the membrane — for instance simply “bitumen roll 4 mm” with no manufacturer — you are not comparing products, you are comparing risks.
Material from the source
Buying membranes factory-direct from Insutech — manufactured in Egypt since 1987, CE-marked, 38 million m² annual capacity — removes import layers from the material side of your cost. Request a project quotation with your areas and application, and our team prices the exact system, not a generic roll.