Can I DIY pressure wash my Ottawa interlock driveway?

Yes, you can safely pressure wash your Ottawa interlock driveway yourself, but you need to use the right technique and pressure settings to avoid damaging the pavers or washing out the jointing sand.

Pressure washing interlock is more delicate than cleaning concrete or asphalt because the pavers are individual units held together by sand in the joints. Use a maximum pressure of 1,500 to 2,000 PSI with a wide-angle nozzle (25 to 40 degrees) to avoid blasting sand out of the joints or chipping paver edges. Start with lower pressure and increase gradually if needed. Hold the nozzle at least 12 inches from the surface and work systematically across the driveway.

Timing matters significantly in Ottawa's climate. The best time to pressure wash interlock is late spring (May to June) after winter salt and debris have been cleared but before summer heat sets in. This gives you time to reapply polymeric sand before fall freeze-thaw cycles begin. Avoid pressure washing during Ottawa's freeze-thaw season (November through March) as wet joints can freeze and cause paver displacement.

Expect to lose some jointing sand even with careful technique — this is normal and why pressure washing should be followed by sand replacement. After washing and allowing 24 to 48 hours to dry completely, sweep fresh polymeric sand into the joints, compact lightly with a rubber mallet or hand tamper, sweep excess sand, and activate according to manufacturer instructions with a gentle water mist. In Ottawa, plan to reapply polymeric sand every 3 to 5 years regardless, as freeze-thaw cycles gradually displace even properly installed sand.

Focus on removing specific problems rather than washing the entire driveway unnecessarily. Target oil stains, salt residue, moss growth in shaded areas, and accumulated dirt in low spots. For stubborn stains, pre-treat with appropriate cleaners — degreaser for oil, mild muriatic acid solution for efflorescence (white mineral deposits), and moss killer for organic growth. Always test cleaning products on an inconspicuous area first.

When to hire a professional: If your interlock driveway has widespread settling, loose pavers, or significant sand loss, address these structural issues before pressure washing. A professional can assess whether the base has failed or if simple releveling and sand replacement will solve the problems. Also consider professional cleaning if you have a large driveway (over 500 square feet) or premium natural stone pavers that require specialized cleaning products.