Power Washing in Stow: what's different here
Homes near Assabet River and under the tree cover around Stow grow mildew fast on shaded walls and decks. On Stow jobs, from Stow Center and Lower Village and beyond, we soft-wash siding and roofs at low pressure and save high pressure for concrete only.
About 60% of homes were built before 1980 and 22% before 1940; median year built 1974 (ACS 2020-2024 5-year). Stow homes from around 1974 often have older, more brittle vinyl or aluminum siding and aging pressure-treated decks, which call for soft washing and low pressure along the grain.
Apart from mill villages at Rock Bottom (Gleasondale) and Assabet Village (now Maynard), Stow was mostly sparsely settled farm and orchard land until the 1950s.
The modern butternut squash was developed in Stow in 1944, and part of the town's former WWII army munitions land is now the Assabet River National Wildlife Refuge.
Signs you need this service
- Green algae or mildew on the north and shaded sides of the house
- Black streaks running down an asphalt shingle roof
- A gray, slippery deck or fence
- Dark, stained driveway, walkway or patio pavers
- Exterior painting or deck staining coming up soon
- Spider webs, pollen and grime around windows and soffits
- Getting the house ready to list for sale
What PSI should I use to pressure wash siding, a deck or a driveway?
Match pressure to the surface. Vinyl siding needs soft washing or low pressure with a wide fan tip aimed level; softwood decks about 500–1,200 PSI along the grain; composite decks no more than the maker allows (Trex caps at 3,100 PSI with a fan tip at least 8 inches away); concrete about 2,500–3,500 PSI with a surface cleaner.
These are typical working ranges used in the trade, not a substitute for the manufacturer’s instructions, which always come first. Pressure is only half the story: the nozzle angle and the distance from the surface matter just as much. A 0° or 15° tip held a few inches from cedar can cut furrows into the wood at pressures that would be harmless with a 40° tip held a foot away.
For vinyl, the siding industry association (PEPA) says to hold the wand at eye level and never aim the stream upward, because that forces water behind the panels, and it notes some manufacturers limit pressure or don’t allow power washing at all. For mildew it suggests a mix of 30% vinegar and 70% water.
- Vinyl and painted siding: soft wash or low pressure, wide fan tip, wand level
- Pressure-treated pine and cedar decks: about 500–1,200 PSI, 25–40° tip, with the grain
- Composite decking: per manufacturer; Trex allows up to 3,100 PSI with a fan tip ≥ 8 in away
- Concrete driveways and walks: about 2,500–3,500 PSI with a rotary surface cleaner
- Asphalt shingle roofs: no pressure washing at all
What is soft washing, and when is it better than pressure washing?
Soft washing uses low pressure, close to a garden hose, plus a cleaning solution, usually diluted sodium hypochlorite with surfactant, to kill algae, mildew and lichen before a gentle rinse. It is the right method for asphalt roofs, vinyl and painted siding, stucco and cedar shingles, where high pressure damages the surface or drives water into the wall.
Pressure washing removes dirt by force; soft washing removes the organisms that cause the green and black staining, so the house stays clean longer. On the shaded north side of a New England house, where mildew comes back every year, soft washing usually lasts noticeably longer than a high-pressure rinse.
Cleaning solutions are diluted to the minimum strength that works, and we protect plantings by soaking them before and rinsing them after. Runoff is kept away from storm drains and ponds as much as the site allows.
Can you pressure wash an asphalt shingle roof?
No. The Asphalt Roofing Manufacturers Association warns that high-pressure washing is likely to damage asphalt roofing and should not be used for any purpose. It strips the protective granules and can void shingle warranties. Black algae streaks are removed by applying a diluted bleach solution at low pressure, letting it work 15–20 minutes and rinsing gently.
The ARMA guidance also says not to scrub or brush the shingles, since friction loosens granules, and not to use other chemicals without the shingle maker’s approval. Wet roofs are slippery, which is why ARMA encourages hiring professionals. Algae streaks are cosmetic; a roof with curling or missing shingles needs a roofer, not a wash.
What should never be pressure washed?
Skip high pressure on asphalt roofs, windows and screens, electrical meters, outlets and AC coils, old brick and soft lime mortar, stucco, cedar shingles and any painted surface with loose paint on a pre-1978 home, which may contain lead. These need soft washing, hand cleaning or a different trade altogether.
Lead paint is the big one in older Massachusetts neighborhoods. State lead-safe renovation rules apply when paid work disturbs more than 20 sq ft of painted exterior surface on pre-1978 housing, and blasting off peeling paint is exactly that kind of disturbance. We clean sound paint at low pressure only; if the paint is failing, the right next step is exterior painting prep done with lead-safe work practices, not a pressure washer.
- Asphalt shingle roofs (soft wash only)
- Windows, screens and window seals
- Electric meters, outlets, light fixtures and AC condenser fins
- Old brick, soft lime mortar and stucco
- Cedar shingles and clapboards at high pressure
- Loose or peeling paint on pre-1978 homes (possible lead)
When is the best time to power wash a house in Massachusetts?
From late spring to early fall, on days above freezing day and night. Spring washing removes winter grime and the pollen that feeds mildew, and early fall washing cleans up before winter. Wash decks a few days before staining and siding about a week before painting, and give wood at least 48 hours of dry weather first.
Avoid washing in direct midday sun on hot days, which dries the cleaning solution before it works and can leave streaks. Plan around pollen season too: washing right after the heaviest pollen drop in late spring gives a cleaner result that lasts.
How the job works, step by step
- Walk-around and test spotWe check the siding type, loose or peeling paint, the age of the house (pre-1978 paint is treated as possibly lead), outlets, light fixtures and plantings, then test the method on a small hidden area.
- Protect the house and yardWe close windows, cover outlets, fixtures and meters, move furniture and pre-wet plants and shrubs so they don’t absorb cleaning solution.
- Apply the cleaner at low pressureFor mildew and algae we apply a diluted cleaning solution with a low-pressure soft-wash system and let it dwell, typically 10–20 minutes, without letting it dry on the surface.
- Rinse at the right pressureSiding is rinsed top-down with a wide fan tip, wand held level, never aimed up under the laps. Decks get low pressure along the grain; concrete gets a rotary surface cleaner for an even, stripe-free finish.
- Final rinse and walkthroughWe rinse plants, windows and walkways again, put everything back and walk the job with you. Wood is left to dry before any stain or paint goes on.
What it costs in Massachusetts
These are typical ranges reported by Angi for pressure washing a house in the Boston area. Decks, roofs and hardscapes vary with size, material and condition; your final price comes from a free estimate.
| Job | Typical MA range |
|---|---|
| Average house wash (Boston area) | ≈ $403 |
| Most house washes (Boston area) | $293 – $519 |
| House washing per square foot | $0.13 – $0.65 / sq ft |
| Driveway (national typical range) | $100 – $500 |
| Deck, fence, patio or roof soft wash | Quoted by size on site |
Source: Angi — Cost to pressure wash a house in Boston, MA