Roof Cleaning and Soft Washing in the Waltham Area
Roof algae is the most common thing we get called about, and it is also the thing homeowners most often get talked into handling the wrong way. A pressure washer will take the streaks off. It will also take a meaningful share of your protective granules with them, and on a roof that is already ten or fifteen years old that trade is not worth making. We soft wash instead, which means low pressure and a cleaning solution that kills the organism at the root so it does not come straight back.
Before and after pair of the same roof slope, shot from the same spot. This is the highest-converting image on the site.
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- Waltham based
- MA HIC #130145 · MA CSL #093926
- Fully insured, workers' comp on file
- Soft wash methods approved for asphalt shingles
- Se habla español
What the black streaks actually are
Gloeocapsa magma, a blue-green algae that arrived in New England decades ago and has been spreading since. It feeds on the limestone filler used in modern asphalt shingles. It travels by air, which is why one house on a street getting streaked usually means the neighbours are next, and it settles heaviest on north-facing and shaded slopes where the roof dries slowest. Under the mature tree canopy across Belmont, Weston and Lexington, that is most roofs.
Beyond how it looks, the algae mat holds moisture against the shingle surface. Sustained dampness shortens shingle life and gives moss somewhere to establish, and moss lifts shingle edges and lets water track underneath.
Soft washing versus pressure washing
Pressure washing a roof
Pressure washing a roof means driving water at the surface hard enough to dislodge material, and shingles are not built for it. The Asphalt Roofing Manufacturers Association guidance on cleaning asphalt shingles is consistent on this point, and some manufacturer warranties are explicit that high-pressure cleaning voids coverage.
Soft washing
Soft washing runs at roughly garden hose pressure with a cleaning solution that kills algae, moss and lichen at the root. We rinse gently, we pre-wet and rinse the surrounding plantings, and we mask off anything sensitive before we start. It takes longer than blasting it. It is also the reason the result lasts and the roof does not pay for it.
What a roof cleaning looks like
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We walk the property and look at the roof, the gutters and the plantings underneath, and give you a written price before anything happens.
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Plantings and shrubs get pre-wet and covered. Downspout runoff gets managed.
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The solution goes on at low pressure and is given time to work.
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Gentle rinse, then a second pass on any heavy areas.
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We clear the debris that comes down, check the gutters, and walk the finished job with you.
How long does it last
On most roofs in this area, three to five years before streaking is visible again. Heavily shaded roofs with overhanging limbs are at the shorter end of that. If you want to stretch it, trimming back branches that keep the roof damp does more than anything else. We can also install zinc or copper strips at the ridge, which release a small amount of metal in rainwater and slow regrowth on the slopes below.
When cleaning is not the answer
If the shingles are curling, cupping, losing granules in quantity, or the roof is past twenty years old, cleaning it is putting money into something that needs replacing. We hold a Massachusetts Construction Supervisor License and we do roof replacement as well, so we have no reason to sell you a wash on a roof that is finished. We will tell you which one you are looking at.
Roof repair and replacementRoof cleaning cost in the Waltham area
[FILL WITH REAL RANGES. Do not publish invented pricing. Once the client gives real numbers, state a range by roof size and pitch and say plainly what moves the price: steep pitch, multiple stories, heavy moss, difficult access.]
This placeholder is deliberate and is on the gaps list. Either it gets real numbers before launch or the whole section comes out.
Frequently asked questions
Will soft washing damage my shingles?
No. Soft washing runs at roughly garden hose pressure and uses a cleaning solution to kill the algae rather than force to remove it. High pressure washing is what damages shingles, because it strips the protective granules, and some manufacturer warranties are explicit that it voids coverage.
Is the cleaning solution safe for plants and pets?
We pre-wet and cover plantings before any solution is applied and rinse thoroughly afterward. Keep pets indoors while we are working and until the surfaces have dried.
Do you need to get on the roof?
Only where the slope and the condition of the shingles allow it safely. Soft washing is done at low pressure and most of it can be reached from ladders and from the ground, which is part of why the method is easier on the roof than pressure washing is.
How long does the job take?
Most single-family roofs are a same-day job. Steep pitch, multiple stories, heavy moss and difficult access all add time, and we tell you what to expect when we give you the written price.
Do you clean moss as well as algae?
Yes. The same low-pressure solution kills moss and lichen at the root along with the algae. Moss matters more than algae does structurally, because it lifts shingle edges and lets water track underneath.
What time of year is best for roof cleaning in Massachusetts?
Anywhere from late spring through fall, once temperatures are consistently above freezing. Summer is when algae streaking is most visible, and fall pairs naturally with gutter cleaning before winter.
Get a free roof cleaning estimate
Tell us the town and roughly how old the roof is. We give you a written price, and if the roof is past the point where cleaning helps we will tell you that instead.
Prefer to talk it through? Call (508) 745-9333.
Se habla español. Puede llamarnos o escribirnos en español.