Expansion joints

The place waterproofing is most often lost.

Joint replacement, sealant renewal and proper termination detailing — the small percentage of a deck that causes most of the leaks.

Request a site assessment Call (236) 873-2580

The work

Joints move, and sealant has a service life.

An expansion joint exists because the structure needs to move. That means the material in it is being cycled constantly, and unlike the membrane either side of it, it is a wearing component with a service life measured in years rather than decades.

When it fails, it does not leak politely across the deck. It delivers water directly to one line, which is why the classic symptom is a persistent drip in the same stall or the same office ceiling tile while the rest of the parkade looks fine.

Replacement means removing the old sealant and backer completely, cleaning and often re-profiling the joint faces, priming, installing correctly sized backer rod, and tooling the new sealant to the right hourglass profile. Sealant squeezed into a dirty joint over the old material is a six-month repair.

Typical sealant life: 5–10 years
Backer: Correctly sized, closed cell
Profile: Tooled hourglass
Common symptom: One persistent drip line

Detail

Termination detailing is the other half of the job.

Wherever a membrane meets something that is not the deck — a curb, a column, a wall, a drain, a joint — there is a termination, and that is where systems fail. Getting these right is unglamorous, invisible when done well, and the difference between a deck that stays dry and one that does not.

When we quote a membrane we quote the detailing explicitly. If you are comparing quotes and one is noticeably cheaper, this is the first place to look for what has been left out.

Questions we get

Straight answers.

Can you just top up the old sealant?

No. New sealant will not bond reliably to aged, dirty or already-failed sealant, and a top-up traps the failure underneath where you cannot see it. The old material comes out.

How do we know the joint is the leak?

The pattern usually tells us: joint leaks track a straight line and appear in the same place every time it rains, while membrane failures produce more diffuse staining. Where it is genuinely ambiguous we can water-test a section.

Can joints be done without replacing the whole membrane?

Yes, and often that is exactly the right scope — if the field of the deck is sound and the joints have simply aged out, replacing joints alone is a fraction of the cost of a full re-membrane and buys the deck years.