Exterior Excavation Waterproofing · Kitchener

Exterior Waterproofing in Kitchener: Dig, Membrane, Drain

Exterior waterproofing is the expensive option and the only complete one. Everything else manages water after it has reached the wall. This stops it getting there. Whether your lot allows it is the first question.

Every basement wall in Kitchener was supposed to have this done when the house was built: a coating on the outside of the wall, drainage at the footing, and backfill that lets water fall to the tile instead of sitting against the concrete. In the 1960s and 70s that meant a thin coat of tar on a block wall and clay tile laid by hand, and after fifty years in Kitchener clay neither is doing anything. Exterior waterproofing is doing that job again, properly, with materials that will last as long as the house.

When exterior is the right answer

• Water is coming through the wall, not up through the floor. Damp block faces, water at the mortar joints, efflorescence and staining across a wall mean the wall is saturated. Only exterior work keeps it dry.
• The wall is block or stone. A block wall's cores fill with water and hold it. A stone wall's joints are open. An interior system catches what comes through; exterior stops it coming through at all.
• You plan to finish the basement. A dry wall is a better thing to build against than a managed wet one.
• The outside is reachable. Lawn or garden along the wall, no driveway, deck, porch, addition or neighbouring house in the way. This is what rules exterior out on many older Kitchener lots, and where it does, an interior system is the practical answer.

What the job involves

Locates. Gas, hydro, water, telecom and anything else buried along the wall are located through Ontario One Call before any digging. Private lines — sprinklers, a line to a garage or shed — are your job to point out.

Excavation. A trench is dug along the affected wall down to the bottom of the footing, wide enough to work in. Plants, steps and paving in the way come out. On a tight lot the soil goes on plywood on the lawn or into bins. Excavation near the Grand River or Schneider Creek may need a Grand River Conservation Authority permit.

Wall preparation. The wall is pressure-washed and scraped back to clean block, stone or concrete. Old tar is removed where it has failed. Holes, spalled block faces and open joints are patched with a cementitious parge so the membrane has a smooth surface. This is surface repair only; a wall that is bowing or has a structural crack is a foundation contractor's job and it is flagged, not membraned over.

Membrane. A rubberized asphalt or elastomeric membrane is applied across the whole wall from grade to the footing, and over the top of the footing, sealed at every pipe penetration. Sprayed or sheet, it is a continuous waterproof skin. Cracks that leak but are not moving are sealed under it.

Dimple board. A dimpled plastic drainage board goes over the membrane. It protects the membrane from the backfill and gives water an air gap to fall through to the tile instead of pressing on the wall.

Weeping tile. New perforated pipe is laid beside the footing in a bed of clear stone, wrapped in filter cloth to keep the clay out, and connected to the sump or to the storm connection, never to the sanitary sewer. If the existing tile on the rest of the house is sound, it is tied in; if it is not, that is the weeping tile conversation.

Backfill and grading. The trench is backfilled in lifts, clear stone against the wall and the original soil above it, and the surface is graded to fall away from the house. Downspouts are extended. Sod and plants go back where they can.

Kitchener block walls

The 1960s to 80s block foundations in Forest Heights, Stanley Park, Centreville and Country Hills are the walls most often waterproofed from outside. The block is porous, the cores fill with water, and by the time the basement is wet the whole wall is saturated. Exterior work dries the wall out over a season. On these houses the tile is usually replaced at the same time, because fifty-year-old tile in clay is rarely worth keeping.

Stone foundations

Exterior waterproofing of a rubble-stone wall downtown, in Cedar Hill or around Victoria Park is possible and often the best answer where the lot allows the dig. The wall is parged smooth before the membrane goes on, and the footing — if there is one — is found by hand rather than assumed. Loose stones found during the dig are a foundation contractor's work and the two trades coordinate; the membrane does not go on until the wall is sound.

Partial versus whole house

Often only one or two walls are wet — the side facing the neighbour's higher lot, the back wall under the patio, the corner where the downspout was. Waterproofing those walls and leaving the dry ones alone is a reasonable way to spend the money, provided the tile connects properly. Doing the whole perimeter is the complete answer and costs proportionally more. The quote prices both where both make sense.

What it does not do

Exterior waterproofing keeps water off the wall. It does not lower a high water table under the floor; that is a sump. It does not stop a wall that is bowing under clay pressure; that is structural. It does not fix a window well with no drain; that is its own job, usually done at the same time since the trench is open. The first visit sorts out which of those you have.

Frequently asked questions

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