Should I pressure wash my house before painting the exterior in New Brunswick?

Yes — pressure washing before exterior painting is essential in New Brunswick, and skipping it is one of the most reliable ways to guarantee early paint failure. Paint simply will not bond properly to a surface covered in dirt, algae, mildew, chalked old paint, or salt residue, and NB's climate gives every one of those problems a chance to develop.

New Brunswick's Maritime humidity and relatively mild summers create ideal conditions for algae and mildew to colonize exterior walls, particularly on north- and east-facing surfaces in shadier spots. Shediac, Miramichi, and Saint John waterfront homes often have a greenish film of algae across their clapboard or vinyl siding by late summer. That biofilm is alive, and if you paint directly over it, the new paint acts as food and the mildew grows right through it within a season. A thorough pressure wash with a mildewcide cleaner — or a mix of one part bleach to three parts water — kills and removes the growth before you ever pick up a brush.

Chalking is another NB-specific concern worth mentioning. Older acrylic and alkyd exterior paints break down under UV and weathering, leaving a chalky, powdery residue on the surface. You can test for it by running your finger firmly across the wall — if it comes away with a white powder, you have chalking. Paint applied over significant chalking will delaminate as the chalk continues to release from the substrate. A good pressure wash strips that layer away and reveals solid, clean paint underneath that new coatings can bond to.

Practical approach for NB homeowners: Rent or hire out a pressure washer capable of 1,500 to 2,500 PSI. Higher pressure is not always better — too much force on cedar shingles, older clapboard, or softened wood can raise the grain, drive water deep into the wood, and damage siding. Keep the wand moving, hold it at an angle rather than perpendicular to the surface, and work from top to bottom. After washing, add a mildewcide rinse or TSP (trisodium phosphate) wash for walls with visible mildew. Then — and this is the part NB homeowners most often rush — wait a minimum of 48 to 72 hours before painting, longer if the weather is cool or overcast. Wood must get below 15% moisture content before paint goes on. A 0 moisture meter from any hardware store will confirm when you're ready.

If the job involves a two-storey home, significant mildew, or heavy chalking across the full exterior, hiring a professional who will pressure wash, treat, rinse, and prep the surface before their crew starts painting is money very well spent. The quality of the wash determines the quality of the paint job that follows it.

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