House Washing Before Painting: Why Prep Cleaning Makes the Paint Last
A new coat of exterior paint is only as good as what is underneath it. Paint over dirt, algae or chalky old paint and it cannot grip properly, so it starts peeling and flaking long before it should. In the Lower Mainland, where algae and grime build fast, prep cleaning is not optional if you want the job to last.
Here is why the wash matters and how it fits into a painting project.
Paint bonds to clean, sound surfaces only
Exterior surfaces here carry a film of algae, dust and pollution, and older painted surfaces develop a chalky layer as the old paint breaks down. New paint applied over any of that bonds to the film, not the wall, so it lets go early, peeling, blistering and flaking within a season or two instead of lasting years.
Washing removes the algae, grime and loose chalk so the fresh paint grips the actual surface. It is the single biggest thing you can do to make an exterior paint job last, and it is invisible once the paint is on, which is exactly why it gets skipped by anyone cutting corners.
The right wash for the surface
The method depends on what you are painting. Siding, stucco and wood get soft washing, which lifts the growth and grime without forcing water behind the surface or damaging it. Concrete and masonry can take pressure washing. The point is the same either way: a clean, sound surface for the primer and paint to bond to.
The surface also has to dry properly before painting. Trapped moisture under fresh paint causes blistering, so the wash is timed to leave enough dry days before the painters start.
Fitting it into the project
The order is simple: wash first, let it dry, then paint. If there are repairs to do, siding, trim or caulking, those come after the wash and before the paint. Coordinating the clean a few days ahead of the painters keeps the whole project on schedule.
Whether you are painting yourself or hiring it out, booking the prep wash is cheap insurance on a paint job that costs far more. A couple of photos and your home's size are enough for a free quote on the wash.