Basement Waterproofing Membrane Explained: What's Under Your Foundation

A basement waterproofing membrane is the single most important component of an exterior waterproofing job. Cheap out here and the whole system fails in a decade.

What a membrane actually does

It's a thick, flexible, waterproof layer applied directly to the outside of your foundation wall. Its job: stop liquid water from contacting the concrete.

Common types

**Asphalt-based dampproofing** (the cheap stuff). What builders sprayed on most pre-2000 Markham homes. Brittle. Cracks within 10–15 years. Technically not waterproofing — it's "dampproofing."

**Rubberized membrane** (modern standard). Thick rubber-asphalt coating, trowelled or sprayed. Flexible, self-healing for small punctures, lasts 30+ years.

**Sheet membrane**. Pre-formed rubber sheets adhered to the wall. Excellent quality, more labour-intensive.

What we use

Heavy-duty rubberized membrane plus a high-impact dimple board. Combined system carries our written workmanship warranty.

Get a free inspection in Markham

If you've noticed dampness, cracks, or musty smells in your basement, don't wait. We offer free on-site inspections across Markham, Unionville, Cornell, Berczy Village, Cathedraltown, Markville and Thornhill — and our work is backed by a written workmanship warranty.