Waterproofing covers the membranes, coatings, and drainage work that keep water out of places it shouldn't be: basement walls and slabs, foundation exteriors, below-grade parking structures, balconies, and flat or low-slope roof decks. In Mississauga, where clay-heavy soil and freeze-thaw cycles put steady pressure on foundations, this often overlaps with roofing work, especially on flat roofs and roof-to-wall transitions where leaks tend to start. We've listed 119 businesses in this category, ranging from small basement-waterproofing crews to larger contractors who handle both roofing and below-grade systems.
What the work actually involves
Interior fixes like sump pumps and interior drain tile handle symptoms but don't stop water from reaching the wall. Proper waterproofing usually means excavating to the footing, repairing cracks, applying a rubberized or bituminous membrane, and installing exterior weeping tile before backfilling. On roofs, it's about torch-on or self-adhered membranes, proper flashing at parapets and drains, and slope that actually moves water to a scupper or drain instead of pooling.
What to check before you hire
Ask for the membrane brand and warranty terms in writing, not just a verbal promise. Find out whether the crew pulls permits when excavation is involved, and whether they've handled your specific problem before (a wet basement corner is a different job than a leaking flat roof deck). Get a written scope that separates labour, materials, and any drainage or grading work, since vague quotes are where costs creep.
How we score contractors
Our ranking weighs verified reviews, licensing and insurance, years doing waterproofing specifically (not just general roofing), and responsiveness to quotes. Full details are on our methodology page. For a ranked shortlist that includes waterproofing-capable roofers, see our best roofing contractors in Mississauga guide.
