Interlock fails in a predictable order, and almost every expensive repair we are called to could have been a cheap one eighteen months earlier.
The failure sequence
- Joint sand washes out. Rain, snowmelt and pressure washing carry it away. The gaps between pavers start to look dark and open.
- Weeds and ants move in. An empty joint is a planter. Roots and tunnelling loosen things further.
- Pavers start to rock. With nothing locking them laterally, individual stones shift under a car tyre.
- Edges drop. Once the perimeter loses support, whole sections settle — and now you are lifting and relaying, not maintaining.
Stages one and two are inexpensive to fix. Stage four is a rebuild. The entire economics of interlock maintenance is about not letting it get past stage two.
What sealing does and does not do
Sealer is a surface treatment. It locks polymeric sand in place, slows staining, resists oil, and holds the colour against UV fade. Those are real benefits and worth paying for.
What it does not do is fix a base problem. Sealing over hollow joints, or over pavers that already rock, buys you a season of looking better while the underlying failure continues. If a contractor quotes sealing without mentioning the joints, they are quoting the easy half of the job.
A proper job, in order
- Pressure clean the surface and flush the joints out completely.
- Treat efflorescence and organic staining before anything is sealed in.
- Re-sand with polymeric sand, worked fully into the joints.
- Let the surface dry — usually overnight.
- Apply a breathable, non-yellowing sealer.
The drying step is the one that gets skipped when a crew wants to finish in a day. Sealing a damp surface traps moisture and produces a cloudy white haze that is genuinely difficult to reverse.
Timing in this climate
Sealing needs dry weather and workable surface temperatures, which in the GTA means roughly May through mid-September. New interlock should go through a full season before its first seal so it can cure and release its efflorescence. After that, most driveways here want re-sealing every three to four years — sooner on a south-facing slope that takes full sun and heavy salt.