Washing the exterior of a house is more than just pulling out the hose: the right method depends on the type of siding, and using the wrong pressure setting costs more than the dirt it removes. Brick can’t handle more than 400 lb/in² at the nozzle, whereas dirty vinyl cleans up very well at low pressure with the right detergent.
Key points to remember
- The surface material dictates the method, never the other way around: brick, vinyl, aluminum, wood, and stucco do not have the same tolerance for pressurized water.
- Maximum 400 lb/in² on brick, using a fan nozzle set at 25 to 50 degrees and held at least 12 inches from the surface, according to the Brick Industry Association’s technical note.
- Pre-wetting is done at less than 100 lb/in², and the cleaning solution is applied at between 30 and 50 lb/in²: it’s the product that does the work, not the spray.
- Mold needs water and nutrients to grow, which explains the black streaks on shaded, poorly ventilated building facades.
- An annual wash is part of preventive property maintenance, just like cleaning the gutters and inspecting the caulking.
- Two or more stories: The work should be entrusted to a professional equipped to reach these areas without using an unstable ladder.
On vinyl, rinsing is done from top to bottom at low pressure.
Why Should You Wash the Exterior of Your House?
A dirty exterior coating isn’t just a cosmetic issue. The green or black film that forms on the north-facing side traps moisture against the material, and that trapped moisture is exactly what mold needs to grow, as the Government of Quebec points out. On vinyl siding, this layer accelerates discoloration. On wood, it damages the finish, and a damaged finish allows water to seep in.
CAA-Québec also includes inspecting siding and caulking on its spring maintenance checklist: poorly secured materials, peeling finish, signs of mold, and whitish efflorescence deposits. An annual cleaning is the perfect time to spot these issues before they require costly repairs. This follows the same logic as Écohabitation’s comprehensive maintenance schedule: small, regular steps rather than a big bill.
Pressure Washing vs. Gentle Washing: The Real Difference
High-pressure washing relies on the mechanical force of water. It works best on concrete, pavers, low walls, and parking lots, where nothing is likely to be dislodged by the water jet.
Gentle cleaning works differently: a cleaning solution does the chemical work; you let it sit, then rinse with low pressure. This is the recommended method for walls, because pressurized water sprayed upward can seep behind the siding and into the structure. Our article on choosing between gentle washing and pressure washing details the edge cases.
Rinsing pressure guidelines based on the coating.
Which method should be used for each type of flooring?
| Coating | Recommended method | Avoid at all costs |
|---|---|---|
| Brick and Stone | Cleaning solution applied at low pressure, rinsing at 100 to 400 lb/in² | Over 400 lb/in² at the nozzle, concentrated jet nozzle |
| Vinyl | Gentle cleaning, soft brush, rinse from top to bottom | Water jet directed upward under the planks |
| Aluminum | Mild detergent and low-pressure rinsing | Abrasive products that dull the painted finish |
| Wood and Engineered Wood | Low-pressure cleaning in the direction of the grain | High pressure that lifts the fibers and opens up the finish |
| Acrylic plaster and stucco | Gentle washing only, extended contact time | Any pressure that dislodges the aggregate |
| Concrete, pavers, stairs | High-pressure cleaning with a rotating nozzle | Failing to rinse sand joints |
The specifications for brickwork are not a matter of contractor preference. The Brick Industry Association’s technical note, “Cleaning Brickwork,” is explicit: use a 25- to 50-degree fan nozzle, held at least 12 inches from the brick, maximum pressure of 400 lb/in² measured at the nozzle, pre-wetting at less than 100 lb/in², and application pressure between 30 and 50 lb/in². As for vinyl, compliant products must meet the ASTM D3679 standard described in the Vinyl Siding Institute’s installation manual: a durable material, but one designed to be installed in overlapping panels, and therefore susceptible to damage from a poorly aimed spray.
The right time of year
On the North Shore, the optimal window extends from the thaw until the first frosts. Spring washes away the salt, calcium, and sand that have been sprayed onto walls and driveways during the winter. Fall removes pollen, grass clippings, and organic deposits before they spend the cold season stuck to the siding.
| Period | Priority | Why Now |
|---|---|---|
| April through May | Walls, entryway, stairs, windows | Winter de-icing salt residue and efflorescence to be removed |
| June through August | Deck, patio, furniture, fences | Quick drying and ideal temperature for the products |
| September through October | Siding, gutters, soffits | Final cleanup before the first frost; leaves need to be removed |
| November through March | Do not wash walls | Risk of water freezing in joints and cracks |
One thing that’s often overlooked: gutter washing and cleaning should be planned together. A clogged gutter will cause water to run down the wall, and in just one downpour, it will leave the same mark you just cleaned away.
The brick is back-filled at a pressure between 100 and 400 lb/in², never more.
The Most Costly Laundry Mistakes
There are four common mistakes that keep cropping up at the properties we inspect. Aiming the spray upward under vinyl siding or soffits: water gets in but doesn’t come out. Cleaning in direct sunlight: the detergent dries before it has a chance to work and leaves streaks. Using a bleach-based product without protecting the vegetation, which burns the hedges and flower beds at the base of the wall. And working from the bottom up, which causes dirt to run down onto surfaces that are already clean.
The fifth mistake isn’t a technical issue—it’s a matter of height. A ladder leaning against a wet surface, a hose that recoils with each trigger pull—and you can quickly lose your balance. Working from the ground remains the best preventive measure whenever possible. Health Canada also reminds us that exposure to mold is a home health issue, not just an aesthetic one; its documentation is available on the Health Canada website. For building-related aspects, CMHC’s guides cover preventive maintenance of the building envelope.
What a Professional Service Can Make a Difference
Three things, specifically. First, the concentration: the solution is tailored to the surface and its condition, which isn’t possible with a consumer-grade bottle. Next, access: second-story walls, cornices, and surfaces above a downspout can be reached using extension equipment, not by climbing a ladder rung. Finally, protecting the vegetation and surrounding structures, which are pre-wetted and rinsed rather than allowed to absorb the product.
An exterior cleaning professional also documents what they see while working: oil stains on the driveway, cracked caulk around the windows, stone joints that need to be repointed, early signs of mold on the north wall, and roof granules accumulated in the gutter. This inspection is often just as valuable as the cleaning itself, because it alerts you to damage before it gets worse.
Safety is part of the service, not an option: safety harnesses, protection of adjacent surfaces, and products recommended by coating manufacturers. The result is high-quality work that restores the property’s appearance without subjecting it to further damage. The final rinse is always done from top to bottom, at low pressure, keeping the surface wet until the very end. This is also the best time to wash the windows: they’re already wet, and the frames are clear. For an entire house, see our full range of exterior maintenance services.
When it comes to water consumption, a gentle, well-executed wash uses significantly less water than a prolonged high-pressure wash on the same surface—a principle of efficiency documented by the EPA’s WaterSense program. Less pressure, more contact time, less water.
Frequently asked questions
How often should you wash the exterior of a house?
Once a year is sufficient for most properties. Shaded facades, homes surrounded by mature trees, and properties along salted roads benefit from a second treatment in the fall.
Can pressure washing damage my siding?
Yes, if the pressure and nozzle are not appropriate. On brick, exceeding 400 lb/in² at the nozzle or bringing the spray wand within 12 inches can erode the mortar and the facing.
Do you need detergent, or is water enough?
Water alone removes dust, but not algae or mold. A cleaning solution applied at low pressure, with sufficient contact time, is what actually eliminates the biofilm.
Does washing kill mold on the exterior walls?
Cleaning removes what is visible. To prevent the stain from reappearing quickly, you must also address the source of the moisture: an overflowing gutter, water running toward the foundation, or vegetation growing against the wall.
How much does it cost to have the exterior of a house washed?
The price depends on the square footage, the type of flooring, the number of floors, and the severity of the stains to be treated. Exterior cleaning is always priced based on a quote provided after an on-site inspection of the property. Our maintenance services are also available as an annual package.
Can I clean my house myself?
For a single-story bungalow, yes—using low-pressure equipment and the right cleaning solution. However, as soon as you need to work at heights or touch the masonry, the risk of damage and falls makes it necessary to hire a professional service.
Ready to restore your property to its former glory?
Squidgee Cleaning services clean exterior siding, windows, and gutters on the North Shore, in Laval, Blainville, Terrebonne, and Bois-des-Filion. Request a quote, and we’ll determine the best method for your siding. Contact us or learn more about our annual maintenance packages.
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