If there's one place in the country where driveway sealing isn't optional, it's Ontario. Our freeze-thaw cycles are an asphalt destruction machine: water seeps into tiny surface pores, freezes, expands, and pries the driveway apart from the inside — over and over, all winter. Sealing is what keeps the water out. The question is when to do it, and how often.
The best time of year to seal in Ontario
Sealant needs warmth to cure properly. The sweet spot is late May through early October, when daytime temperatures reliably stay above 10°C and no rain is expected for 24–48 hours after application. Mid-summer is ideal — long warm days cure sealant fastest — but a dry September weekend works just as well and gets your driveway protected right before the winter that does the actual damage.
What you want to avoid is sealing too late in fall. Once overnight temperatures start dipping toward freezing, sealant cures slowly or unevenly and won't bond properly. If you've missed the window, it's genuinely better to wait for spring than to seal into cold weather.
How often should you reseal?
For most driveways in Milton, Oakville and Mississauga, every 2–3 years is right. Sealing more often than yearly doesn't add protection — it just builds up layers that can flake. Sealing less often than every 3–4 years leaves the asphalt exposed exactly when our climate is hardest on it.
One important exception: a brand-new driveway should not be sealed right away. Fresh asphalt needs to cure and release oils first. Wait at least one full year (some installers say two) after paving before the first seal.
Signs your driveway is overdue
- Fading: the surface has gone from black to grey. Grey asphalt is dried-out asphalt — the binder that holds it together is oxidizing away.
- Hairline cracks: small cracks are the entry points for water. Sealed early, they stay small. Ignored, they become the wide cracks and potholes that need expensive repair.
- Water soaks in instead of beading: after rain, a sealed driveway sheds water. If yours darkens and absorbs it, the protective layer is gone.
- Rough, pitted texture: loose gravel appearing on the surface means the top layer is breaking down.
Why proper prep matters more than the sealant
The difference between a professional seal job and a quick one isn't the bucket — it's the preparation. The surface needs to be thoroughly cleaned and fully dry, cracks filled, and oil spots treated so the sealant bonds instead of peeling. A rushed job over a dirty driveway looks fine for a month, then flakes off in sheets. When you hire it out, ask how the surface will be prepped; the answer tells you everything.