WATstop interior waterproofing
Water coming through the basement wall?
Seal it from the inside. WATstop is a three-part epoxy-cement that rolls onto bare concrete and holds back 139.6 psi of water pressure. Two coats now, paint over it in two days.
Why interior waterproofing is different
The water is on the wrong side of the wall
Waterproofing usually goes on the outside of a foundation, where the ground water presses the coating onto the wall. In a finished basement you're working from the inside, and the same pressure is now trying to push the coating off. That force is called counter-thrust, and it's the number that matters for an interior job.
WATstop is rated to 9.5 atmospheres of counter-thrust pressure. That's 139.6 psi, the push of a column of water over 300 feet tall standing behind your wall. It bonds to concrete at 2.5 N/mm² and rides out 50 freeze-thaw cycles unchanged, so a Canadian winter doesn't reopen the problem.
A weekend-sized job
How it goes on
Mix in the bucket
Stir the cement part into water until it's a smooth paste, add the resin, then the catalyst. Everything comes pre-dosed in one kit, and you have about 2 hours of working time per mix.
Roll on two coats
First coat onto bare concrete, masonry or even old tile. Second coat within 24 hours. A short-hair roller or a trowel both work; it dries in 5 to 12 hours. At the wall-to-floor joint and in the corners, press Safety Joint Roll into the fresh first coat and let the second coat cover it completely.
Make it a wall again
Paint, plaster or tile go straight over WATstop 24 to 48 hours after the last coat. The problem disappears and the room goes back to being a comfortable space.
Coverage calculator
How much do you need?
Based on 2.0 kg per m² for full waterproofing and 1.0 kg per m² for a vapour barrier, applied in two coats. Rough or very porous surfaces take a little more, so round up if you're between sizes. Joints take one metre of Safety Joint Roll per metre treated; each roll carries 20 m (about 65 ft).
Two sizes, one product
Pick your bucket
WATstop 5 kg
$206.99
- Full waterproofing: about 27 sq ft
- Vapour barrier: about 54 sq ft
- The right size for one problem wall
WATstop 10 kg
$319.99
- Full waterproofing: about 54 sq ft
- Vapour barrier: about 107 sq ft
- The better value per square foot
Safety Joint Roll
$96.40
- Elastic non-woven polyester tape for the wall-to-floor joint and corners
- 20 m roll, 15 cm wide: about 65 linear ft
- Pressed into the first coat, covered by the second
Water actively running in? Call us first.
A damp or seeping wall is exactly what WATstop is made for. A crack that's moving, or water streaming in while it rains, earns a conversation first because sometimes WATstop is the whole fix and sometimes it's the last product that goes on. Five minutes on the phone saves you a return. 1-866-326-8321
Do your homework
