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ROOF WASHING
Roof washing for the Twin Cities north metro
A no-pressure soft wash that kills the algae, moss and lichen streaking your shingles, using the method shingle manufacturers publish.
The dark streaks on so many roofs are not dirt, age or shade. They are Gloeocapsa magma, a living colony that feeds on your shingles. Glass House removes it with a no-pressure soft wash, the same method the major shingle manufacturers publish, and never pressure washes a roof.
Wooded lots, lakes and humid summers give roof algae everything it needs across Anoka County and the surrounding north metro. Left alone, it loosens the granules that protect your shingles and ages the roof years ahead of schedule, and Minnesota insurers now look harder at roofs than they once did.
ROOF WASHING WARRANTY
If treated growth returns, we re-wash the affected areas free in year one, and at half cost in year two.
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Insured to $2M
Owner-operated
Based in Ham Lake
BY THE NUMBERS
Why gentle roof washing matters in the north metro
25–50 yrs
is the length of GAF, Owens Corning and CertainTeed shingle warranties. All three publish a low-pressure cleaning method for roof algae.
300 psi
or less is what our soft wash runs at. A typical pressure washer runs 3,000 to 4,000.
Nearly half
of the Twin Cities' 31.6 inches of yearly precipitation falls in June, July and August, the peak of roof algae's growing season.
387
major hail events struck Minnesota in 2022, the third most of any state. Insurers have looked harder at roofs ever since.
Sources: GAF, Owens Corning and CertainTeed limited warranties; Climate of Minneapolis–Saint Paul, NOAA 1991–2020 normals; Insurance Information Institute, major hail events by state, 2022.
WHAT GROWS ON ROOFS
Roof algae is eating your shingles
It has a name: Gloeocapsa magma
Gloeocapsa magma is a cyanobacteria, usually called blue-green or black algae. It arrives as an airborne spore, often from a neighboring roof, and settles wherever a roof stays damp longest: north slopes and anything shaded by trees. Wooded and lakeside lots give it more of both.
Your shingles are its food
Asphalt shingles are made with a limestone filler, calcium carbonate mixed into the asphalt, and that is exactly what this bacteria feeds on. As the colony grows, it builds a dark outer shell to protect itself from the sun, and that shell is the streak you see from the street.
The granules start letting go
The granules on a shingle are its sunscreen, shielding the asphalt from UV light, and they are held in place by the asphalt and limestone layer. With the colony feeding and holding moisture against the shingle every day, granules loosen. Once they are gone, the asphalt dries out, cracks and curls years early.
Then moss, lichen and winter
The same damp shade invites moss, which holds water like a sponge and lifts shingle edges. Lichen roots into the surface and takes granules with it when it lets go. Then a Minnesota winter drives water under a lifted edge, where it freezes, expands and pries the shingle up further.
SOFT VERSUS PRESSURE
Two very different ways to clean a roof
Pressure washing cleans with force. Soft washing cleans with chemistry and rinses at very low pressure. On a roof, that difference decides whether the granules stay on your shingles.
THE QUESTION
SOFT WASHING (WHAT WE DO)
PRESSURE WASHING
Pressure at the shingle
50 to 300 psi, comparable to a garden hose
3,000 to 4,000 psi
What removes the growth
The treatment kills it where it lives
Force blasts at the surface
Your granules
Left in place
Blasted off along with the growth
Manufacturer guidance
Matches the cleaning method the manufacturers publish
Not the method any manufacturer publishes
The rinse
Often the next rain, the gentlest rinse there is
More high pressure
MANUFACTURER GUIDANCE
The shingle makers already wrote the instructions
Every major manufacturer publishes how to clean algae from its shingles, and none of them calls for a pressure washer.
GAF
A GAF technical bulletin calls for 4 gallons of water, 1 gallon of bleach and 1 cup of TSP, applied with a garden sprayer and left up to 20 minutes, then rinsed with low-pressure water. That is a diluted solution, a measured dwell time and a gentle rinse.
Owens Corning and CertainTeed
Both describe nearly the same process: 1 part bleach to 3 parts water, left about 15 minutes, then rinsed. A diluted solution, a short dwell and a gentle rinse is exactly what soft washing is, which is why our method follows their instructions.
ARMA
The Asphalt Roofing Manufacturers Association puts it plainly: do not use a power washer, or any type of brush or broom, to clean algae from the roof surface. ARMA also recommends that only trained professionals work on a roof, because a wet asphalt roof is dangerous underfoot.
For homeowners doing it themselves, those bulletins are the recipe. A wet, treated roof is slick, however, and falls hurt far more homeowners than chemicals do. Without a secure position to work from, that is the moment to call a professional.
HOW WE WASH ROOFS
Chemistry does the work. Pressure never touches your shingles.
01
Walk-around first
Every online quote is verified in person. Carson looks over the roof, the growth and the landscaping below before any work starts, so the mix suits your roof and any concerns are raised with you before the wash.
Roofs receive a stronger mix than siding, because shingles are porous, plus a surfactant, an additive that helps the mix cling. Time and the weather then finish the job.
CARSON'S FIELD RULE
If the algae turns brown, it is coming down. If it turns black, it is going to come back. That color change is what Carson watches for after the treatment goes on.
02
Protect the landscaping
Plants, shrubs and lawn beneath the drip line are soaked with water before and after the treatment. Any drift that lands on wet leaves is diluted to the point of being harmless, which is how landscaping comes through a roof wash well.
03
Apply as a fine mist
The treatment goes on as a fine mist at 50 to 300 psi and coats the growth completely, with enough surfactant to hold it on the shingles. Nobody scrubs, brushes or blasts your roof at any point.
04
Let the rain rinse it
On many roofs the treatment is left on and the next rain does the rinsing, the gentlest rinse possible for the granules. Each rain reactivates the treatment, so the growth keeps dying and releasing and the roof keeps brightening for weeks after we leave.
05
Photos and a receipt
Every job ends with a walkthrough of the finished roof and before and after photos attached to your receipt, so you can see the result and keep a record of the work.
WHY INSURERS CARE
Minnesota roofs are getting a closer look
Heavy hail years changed things
Minnesota had the third most major hail events of any state in 2022, and the August 11, 2023 Twin Cities storm caused an estimated $1.5 billion in damage. Carriers have been stricter about roofs ever since.
More inspections before renewal
More insurers now inspect a roof before renewing a policy, especially a roof over 10 to 15 years old. Some also ask for documentation from a contractor before they will continue covering an older roof, so a record of maintenance has real value.
Reviews from above
Much of that review happens from the air. Satellite and drone images are run through software that flags roofs that look worn, and from above, a streaked, mossy roof looks neglected, even when the shingles underneath are sound.
A record of maintenance helps
Regulators in some states have told insurers that streaking alone is not grounds to drop a policy, but no homeowner wants to argue that point with a letter in hand. A clean roof, with photos and a receipt from a professional cleaning, shows the roof is being cared for.
Sources: Insurance Information Institute, major hail events by state (2022); Minnesota DNR State Climatology Office, August 11, 2023 hail and winds.
HONEST EXPECTATIONS
What a roof wash can and cannot do
Roof washing typically lands at 70 to 90 percent improvement when we leave, and the roof keeps brightening over the following weeks as the growth dies off and each rain reactivates the treatment, so the result is best judged a few weeks after the wash.
Lost granules do not return
A roof that has been streaked for years has already lost granules to the algae. Washing stops the damage, but it cannot put granules back, so that roof will not look factory-new. We say so at the walk-around, before any work is quoted.
It is not a roof repair
A wash does not fix shingles, flashing, ventilation or drainage, and some staining or regrowth risk can remain until those are corrected. If we notice something that needs a roofer, we photograph it and show you, because Glass House cleans roofs and does not repair them.
Moss and lichen release slowly
Moss and lichen die with the treatment, but they do not always let go right away. Thick moss can take longer to release after it dies. Lichen roots into the shingle, so where it has grown for years, bare spots can remain once it lets go. We point those areas out before the wash.
PRICE AND WARRANTY
What roof washing costs, and what backs it
YOUR ROOF WASH, AT A GLANCE
NORTH METRO
Roof washing
$800–$1,600
No-pressure soft wash for algae, moss and lichen
Service Plan member on a Preferred day
From $560
25% member rate, plus 5% on a Preferred day
Roof Washing Warranty
Included
Free re-wash of affected areas in year one, half cost within two years
Walk-around and photos
Included
Concerns raised before we start, and a photo record after
Weather reschedules
Always free
Moved to a new date when it is too wet or windy to work safely
BY HOME SIZE
Home size
Roof washing
Up to 2,000 sq ft
$800
2,001–3,000 sq ft
$1,200
3,001–4,000 sq ft
$1,600
Over 4,000 sq ft
Priced by Carson
Typical 2,000–4,000 sq ft home
$800–$1,600
Roof washing typically runs $800–$1,600 — $800 for a 2,000 sq ft home and $1,600 for a 4,000 sq ft home. Yours depends on the home, so Carson confirms the exact price after he looks at it.
WAYS TO SAVE
Fall Promo, through November 30
Free gutter cleaning with a house washing or a roof washing, applied automatically. One offer per quote, so it does not combine with the flash sale; you get the bigger one.
Service Plan members
25% off any other work, holiday lighting included
Preferred day
Another 5% off on top of any other saving, up to 25% in all
Veterans
10% off any service
Seniors 65 and older
$50 off
Same-day neighbors
15% off for both households
Three projects together
10% off
Discounts don't combine — you receive whichever single saving is largest. Then a Preferred day can take another 5% off, up to 25% in all (Service Plan members aren't capped).
This season’s flash sale is shown at the foot of every page.
GUARANTEES
What backs the work, word for word
These are printed word for word on your quote, your work order and your invoice.
INCLUDED
Roof Washing Warranty
If treated organic growth returns within the first year, we re-wash the affected areas free. If it returns within two years of service, we re-wash at half cost.
INCLUDED
Satisfaction Guarantee
If we are not satisfied with the outcome of your window cleaning, gutter cleaning, house washing, or roof washing, you will not be charged.
INCLUDED
Workmanship Standard
If we miss an area or leave normal cleanable residue, tell us and we'll re-clean or touch it up. Our guarantees cover the cleaning result — not repairs, replacements, permanent stains, or conditions that can't be safely corrected through cleaning.
WHAT IS INCLUDED
What a roof wash includes and leaves out
A roof wash kills the growth on your shingles and backs the result with a warranty. Repairs always belong to a roofer.
INCLUDED
In every roof wash
• A no-pressure soft wash of the whole roof, at 50 to 300 psi
• Black algae streaks, moss, lichen, mold and mildew treated
• Plants wet down before and after
• Growth that keeps releasing, so the roof brightens for weeks
• Warranty: affected areas re-washed free in year one, half cost in year two
NOT INCLUDED
Outside a roof wash
• Pressure washing, brushing or scrubbing shingles, ever
• Shingle, flashing, ventilation or drainage repair
• A factory-new look, since lost granules do not return
• Gutter cleaning, unless added to the visit
• Work on a roof too steep or wet that day
EQUIPMENT AND METHODS
The method the shingle makers publish
The soft wash system delivers the treatment as a fine mist at 50 to 300 psi, with a reach of about 85 feet. The roof mix is around 6% sodium hypochlorite with a little surfactant, so it clings to the shingles. On many roofs the rain does the rinsing and keeps the treatment working for weeks, which leaves an even finish.
SAFETY AND CARE
Safe for your shingles, and for everyone below them
A roof is the most dangerous place we work and the easiest surface to damage, so these rules do not bend.
ON THE ROOF
Traction and dry footing
On the roof, Carson wears roofing-specific traction footwear and uses a harness when conditions call for it, and nobody walks on wet shingles. If a roof is too steep or too wet to work safely that day, the job is rescheduled, and weather reschedules are always free.
LADDERS
Weight kept off the gutter edge
Every ladder carries padded standoffs, so the gutter edge never takes the ladder's weight and nothing marks the exterior. Levelers keep the base steady on soft or uneven ground, and ladders are set at a 4 to 1 angle and tied off above two stories.
WASPS
Active nests stop work
Wasp and hornet nests are often found under the eaves, right where a ladder meets the roofline. An active nest makes that area unsafe, so we complete everything else and tell you exactly what was skipped. Our policies ask homeowners to have nests treated before we arrive.
FAMILY
Kids and pets are welcome
Children and pets are welcome at home during a roof wash, and there is no need to keep them inside. We ask only that they stay clear of the ladders and the area below the eaves while the treatment goes on.
THE OWNER
Why Carson follows the shingle makers' method
Glass House is owned and run by Carson Brenny, with no crews, subcontractors or handoffs. He grew up in Ham Lake, went to Blaine High School and has worked full-time in exterior cleaning since 2020. He quotes your roof, treats it himself and walks the finished job with you.
A roof protects everything beneath it: the walls, the ceilings and the people inside. It is also one of the most expensive parts of a home to replace, which is why Carson follows the method the shingle manufacturers publish, and why he says plainly when streaking has already cost a roof its granules.
IN CARSON'S WORDS
“It's my neighbors' homes: their biggest investment, one of the places they spend the most time, and where the people they care about most live. It's something everyone should enjoy, and I believe that.”
Carson Brenny, owner
✓
Follows GAF, Owens Corning and CertainTeed guidance
✓
Roof Washing Warranty: a free re-wash in year one, half cost in year two
✓
Photos and notes on anything seen up there
NORTH METRO TIMING
When to wash, and how often
JULY TO SEPTEMBER
Prime roof washing
Growth is active and easy to kill, and summer rains keep reactivating the treatment after we leave, so the roof keeps brightening.
SPRING & FALL
Still roof weather
Our exterior season runs March 1 through November 15, and roofs can be washed throughout it, with bookings taken well into the fall.
WINTER
No washing
Roofs are not washed in freezing weather. When ice builds up at the roof edge, we remove ice dams with steam only.
HOW OFTEN
Every few years
A soft wash every few years keeps most roofs streak-free. Wash sooner under heavy tree cover or on the water, such as Coon Lake, Crooked Lake or the Rice Creek Chain of Lakes.
Between washes, trim branches that shade the roof or drop debris on it, keep gutters clear so the eaves do not sit wet, make sure the attic vents, and have the roof looked at once a year. When replacing a roof, ask for algae-resistant shingles.
WHERE WE WORK
Roof washing across Anoka County and the north metro
Glass House is based in Ham Lake and washes roofs throughout Anoka County and the Twin Cities north metro, from wooded acre lots to lake homes and newer subdivisions.
Each city page covers the local conditions that affect your home. The surrounding north metro is served as well, and we travel farther for a small trip fee.
ROOF WASHING QUESTIONS
Roof washing FAQ
What are the black streaks on my roof?
They are Gloeocapsa magma, a blue-green algae (a cyanobacteria) that arrives as an airborne spore and feeds on the limestone filler in asphalt shingles. The black color is a protective shell the colony grows against the sun. It is not dirt or age, and it settles where a roof stays damp longest, such as north slopes and shaded areas.
Will roof washing affect my shingle warranty?
Not the way Glass House does it. GAF, Owens Corning and CertainTeed publish their own methods for cleaning roof algae: a diluted bleach solution, a short dwell and a low-pressure rinse. That is soft washing, which we do at 50 to 300 psi. Pressure washing strips the protective granules, and no manufacturer's published method calls for it.
Why is there a clean stripe under my chimney?
That clean strip below chimney flashing or a metal vent comes from copper and zinc washing down in the rain, and the algae cannot live in it. Algae-resistant shingles use the same idea, with copper granules that release a little each time it rains. If you are replacing your roof, ask for them.
Does it kill moss and lichen?
Yes, along with algae, mold and mildew. Thick moss can take a little longer to let go after it dies, and lichen roots into the shingle, so old lichen can leave bare spots where it grew. We point those areas out at the walk-around, before any work starts.
Is it safe for my plants?
Yes. The landscaping is soaked with water before and after the treatment, so any drift lands on a wet surface and is diluted to the point of being harmless. If you have prized plants or a pond, tell us when you book, and we will take extra care around them.
How long will my roof stay clean?
Every few years is typical, and roofs under heavy trees or near water grow back sooner. The Roof Washing Warranty covers treated growth that returns: we re-wash the affected areas free in year one, and at half cost in year two. Trimming overhanging branches and keeping gutters clear also slows the return.
Can I do it myself?
You can follow the manufacturer's bulletin, but a wet, treated roof is slick, and falls are the real danger. ARMA, the roofing manufacturers' association, recommends leaving roof work to trained professionals. Whatever you decide, never use a pressure washer on shingles, because it strips the granules that protect them.
What does it cost?
Roof washing typically runs $800–$1,600 — $800 for a 2,000 sq ft home and $1,600 for a 4,000 sq ft home. Yours depends on the home, so Carson confirms the exact price after he looks at it. The Roof Washing Warranty is included with every roof wash.
Fully insured to $2M
Owner-operated
Locally owned in Ham Lake
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