How do Ottawa contractors handle expansion joints before applying epoxy

Handling Expansion Joints Before Epoxy Application in Ottawa

Ottawa contractors handle expansion joints by honouring them through the finished epoxy coating — meaning the joints are cleaned, filled with a flexible material, and then the epoxy is applied over the entire floor but the joint lines are re-cut through the cured coating afterward. This is the professional standard because expansion joints serve a critical structural purpose: they allow separate concrete sections to move independently with temperature changes and soil settlement. In Ottawa's extreme climate, where slabs experience temperature swings of over 65 degrees Celsius annually, these joints are actively working and must remain functional.

The process begins with thorough cleaning of every joint. Over years of use, Ottawa garage expansion joints accumulate road salt, dirt, oil, and debris that must be completely removed. Contractors use a crack chaser saw or angle grinder to widen and clean the joint edges, then vacuum out all loose material. Any old, failed joint filler — a common sight in Ottawa garages where freeze-thaw cycles destroy cheap caulking within a few seasons — is cut out and removed entirely.

Next, a backer rod (a compressible foam rope) is pressed into the joint to the proper depth, creating a controlled cavity for the sealant. The contractor then fills the joint with a flexible polyurea or polyurethane joint filler — never rigid epoxy. This distinction is critical in Ottawa. Rigid fillers crack when the slab sections move seasonally, while flexible polyurea compounds can stretch and compress through freeze-thaw cycles without failing. Quality joint fillers for Ottawa conditions should have an elongation rating of at least 300 percent. The filler is troweled flush with the surrounding concrete surface so the epoxy system can be applied smoothly over it.

After the full epoxy system is applied and cured (including base coat, flake broadcast or decorative layer, and clear topcoat), the contractor re-cuts the joints through the coating using a diamond blade set to the exact depth of the coating layers. This re-establishes the movement capability of the joint while maintaining a clean, finished appearance. Some contractors mark joint locations with tape before coating to ensure accurate re-cutting.

There are two types of joints to distinguish. Control joints (also called contraction joints) are the shallow saw-cut lines typically spaced every 8 to 12 feet in a garage slab — these can sometimes be filled and coated over without re-cutting in low-movement situations, though most Ottawa contractors re-cut them as a precaution. True expansion joints — typically found where the garage slab meets the house foundation, at the garage door threshold, or between the garage and a porch or walkway slab — must always be honoured and re-cut, as these joints accommodate the most movement.

Joint preparation and treatment in Ottawa typically costs $3 to $8 per linear foot, and a standard two-car garage usually has 20 to 40 linear feet of joints, adding $60 to $320 to the preparation cost. Some contractors include joint work in their overall preparation quote while others itemize it separately. Cutting corners on joint treatment is one of the fastest ways to guarantee coating failure in Ottawa's climate, so confirm this step is explicitly covered in any quote you receive. The Ottawa Construction Network directory at justynrookcontracting.com can help you connect with flooring professionals who understand proper joint treatment for our local conditions.

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