Interior Drainage System · Kitchener
Interior Basement Waterproofing in Kitchener
An interior system does not stop water reaching the wall. It catches it at the footing and takes it away before it reaches the floor. That is a smaller promise than exterior work, and for a lot of Kitchener basements it is the right one.
Half the wet basements in Kitchener cannot be fixed from outside. The wall is under a driveway, a deck, a porch, an addition, or a metre from the neighbour's house. The basement is finished and the owner would rather open a strip of floor than dig up the lot. Or the water is coming up through the floor rather than through the wall, and no amount of membrane on the outside will change that. For all of those, the answer is an interior drainage system.
How it works
A strip of the concrete floor along the affected walls is cut out and removed, about a foot wide, down to the top of the footing. A perforated drain channel or pipe is set in clear stone beside the footing, below the level of the slab, and sloped to a sump pit. Weep holes are drilled into the bottom course of a block wall so the water sitting in the cores drains into the channel instead of through the face of the wall. A dimpled plastic membrane is fastened to the wall from the channel up to a chosen height — often full height on stone or badly saturated block — so any water coming through the wall runs down behind it into the channel rather than onto the floor. The floor is then poured back in concrete, and the membrane is hidden behind the finished wall. A sump pump takes the water out and discharges it outside, to grade, away from the house.
The whole thing is inside. Nothing on the lot is dug. On a straightforward wall it is a job of days.
Where it is the right answer in Kitchener
- Block walls under driveways and decks in Forest Heights, Stanley Park and the east-side subdivisions, where the wet wall is the one the car sits on top of.
- Stone basements downtown, in Cedar Hill and around Victoria Park, where water comes through the joints and up through a thin old floor, and there is no footing or tile to connect to outside. A full-height membrane on the stone with the channel at the base is the standard approach, and the hard cement parging that traps water in the stone usually comes off first.
- High water table lots near the Grand River, Schneider Creek and Strasburg Creek, where the water is under the slab and the system's real job is getting it to the sump before it comes up through the floor-wall joint.
- Finished basements where opening a strip of floor and the bottom of the wall is far less disruptive than excavating outside.
- Semis and close-set houses in the older neighbourhoods where the outside of the shared or near wall cannot be reached.
What it does not do
It is worth being plain about this. An interior system leaves the wall wet on the outside. The block or stone still takes on water; the system just makes sure the water goes into the channel and not onto the floor. That is fine for a basement that needs to be dry and usable. It is not the same as a wall that is dry, and it is why exterior work is recommended where the lot allows it and the wall is the source. It also does nothing for a wall that is bowing or a crack that is moving. Those are structural, a foundation contractor's trade, and they are dealt with before a membrane goes over them.
The sump is part of the system
Every interior drainage system needs somewhere to send the water. In Kitchener that is a sump pit and pump discharging to grade outside, not a floor drain into the sanitary sewer, which the city does not allow for foundation water. The pit is set at the low point of the channel, the pump is sized to the flow, and on a lot where the water table rises in spring a battery backup pump goes in beside it. Discharge goes well away from the wall, onto the lawn or to a storm connection where one exists, and not onto the neighbour's lot.
Finishing after the system
Once the floor is poured back, the basement can be framed and finished. The stud wall is set off the membrane so it stays dry, and nothing is fastened through the membrane below the channel. A few things are worth planning: an access hatch to the sump, a route for the discharge line, and leaving the bottom of the wall reachable if the basement has a history of anything worse than seepage.
Interior on one wall, exterior on another
A lot of Kitchener houses end up with both: exterior on the back wall where the garden allows the dig and the wall is saturated, interior on the side wall under the driveway. The channels and tile connect to the same sump. The first visit walks the whole perimeter, inside and out, and the quote sets out which wall gets which method and why.
Frequently asked questions
Does an interior system actually stop the leak?
It stops water reaching the floor. Water still comes into the wall from outside; the channel at the footing and the membrane on the wall catch it and send it to the sump. For a usable, dry basement that is what matters. If you want the wall itself dry, that is exterior work, where the lot allows it.
Can it be installed in a finished basement?
Yes. The bottom of the finished wall and a strip of flooring along the affected walls come out, the system goes in, the floor is poured back, and the wall is rebuilt off the membrane. It is far less disruptive than opening the lot, which is one reason it is chosen.
Will the system handle a bowing block wall?
No. The membrane and channel manage water; they do not hold a wall. A horizontal crack with the wall leaning in is a structural problem for a foundation contractor, and it is braced or rebuilt before a membrane goes over it. If that is what the first visit finds, you are told so.
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