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ROOF CLEANING

The Asphalt Roofing Manufacturers Association is blunt about this: never use a power washer on an asphalt shingle roof, because it strips granules and shortens the life of the whole system. Their published method is a chemical one, left to dwell for 15 to 20 minutes and rinsed gently. Metro Mobile Pressure Washing cleans shingle, metal, and tile roofs across Fort Washington, MD by soft washing, the low-pressure approach that their own guidance describes. It is the only method we use.
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THE ONLY SAFE ROOF CLEANING IS THE GENTLE KIND.

Every roof we are called to has already been quoted by somebody with a wand and a ladder. That approach removes the streaking, and it removes a measurable share of the granules protecting the shingle along with it. The roof looks better for a season and ages faster for the rest of its life.

Solution and dwell time do the same job without the cost. The growth is treated where it sits, the rinse is gentle, and the surface of the shingle stays exactly as the manufacturer built it.

  • Low-pressure soft washing only
  • Method consistent with published roofing guidance
  • Beds, shrubs, and downspout outlets protected
  • Moss addressed before it lifts shingle edges
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ROOF CLEANING

THOSE BLACK STREAKS ARE ALIVE.

The dark stains running down a roof are not soot, dirt, or age. They are a cyanobacteria called Gloeocapsa magma, feeding on the limestone filler in the shingle and spreading downward with every rainfall. That is why the streaking always runs from the ridge toward the eave, why it appears on one plane before another, and why scrubbing at the color achieves nothing lasting at all.

THE EASTERN SEABOARD IS WHERE THIS GROWTH THRIVES.

Roof algae is most widespread in warm, humid regions, and the mid-Atlantic sits squarely inside that description. Between summer humidity, mature tree canopy, and the shade it casts across the northern roof planes, streaking on homes around Fort Washington is close to inevitable rather than unlucky. What varies is only how soon it appears and how far it spreads. Cleaning it is maintenance, not vanity.

WE TURNED DOWN ROOF WORK RATHER THAN WASH A SHINGLE HARD.

More than once a homeowner has asked us to just run pressure over the roof and be done. We have declined, explained why, and occasionally lost the job to someone who agreed. That position has not changed in 26 years, because a roof is the most expensive surface on the building and there is no undoing granule loss once it happens. Would you rather yours simply lasted longer?

WHY CHOOSE US FOR ROOF CLEANING.

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GRANULES THAT STAY ON THE SHINGLE
The mineral surface is the shingle's protection against sunlight. Cleaning that removes any part of it trades a cosmetic improvement for real service life, which is a poor bargain on a roof.
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A ROOF THAT LOOKS ITS ACTUAL AGE
Streaking makes a sound 10-year roof read as a tired 20-year one from the street. Removing it puts the appearance back in line with the condition, which matters most when selling.
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MOSS GONE BEFORE IT LIFTS EDGES
Moss is the growth that genuinely causes damage, curling shingle edges and raising the risk of blow-off in high wind. Dealing with it early is maintenance rather than repair.
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NOTHING THAT PUTS COVERAGE AT RISK
Shingle warranties cover defects, not damage from improper maintenance. Using the method the manufacturers describe keeps that distinction on your side of the line rather than the insurer's.
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PLANTS AND DOWNSPOUTS PROTECTED
Everything that comes off a roof travels into the gutters and out at ground level. Runoff gets managed and beds get soaked, so the landscaping does not pay for the roof looking better.
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STREET APPEAL FROM THE TOP DOWN
A roof occupies a large share of what anyone sees when they look at a house. Clean shingles change the impression of the whole property more than most owners expect.
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our services

OUR ROOF CLEANING WORK

Roofing materials behave differently and grow different things on them, so the treatment changes with the surface. These are the roof types and problems we handle most often across residential and commercial buildings.
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Shingle Roof Soft Washing

ASPHALT SHINGLE

The standard residential job, handled entirely at low pressure with a dwelling solution. Coverage has to be complete across each plane, since a missed band shows up clearly once the surrounding area brightens.
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Algae and Black Streak Treatment

STREAK REMOVAL

Targeted treatment of the vertical staining running down from the ridge. The solution addresses the organism itself, which is the only reason the result holds beyond a couple of rain events.
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Moss and Lichen Removal

NORTH SLOPES

Shaded planes carry the growth that actually damages a roof. Moss gets treated and allowed to die back rather than scraped off, because pulling it away takes shingle surface with it.
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Metal and Tile Roof Cleaning

METAL AND TILE

Standing seam, corrugated metal, and tile all clean differently from asphalt and tolerate different chemistry. Coatings and finishes get accounted for before anything at all is applied to the surface.
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Flat and Low-Slope Roof Cleaning

LOW SLOPE

Membrane and modified roofs on commercial buildings and additions, cleaned with attention to seams and drains. Ponding areas and drain baskets get checked while we are up there doing the work.
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Roof Edge, Valley, and Overhang Cleaning

ROOFLINE

Valleys, eaves, overhangs, and the first course above the gutter collect debris and growth first. These edges are visible from the ground and they are exactly what a rushed job leaves behind.
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THE WORD ON OUR WORK

WHAT OUR CLIENTS SAY.

Roof work draws the biggest reaction of anything we do, because the change is visible from the end of the street. Several customers have told us neighbors asked who did it within days, which is a compliment and a referral in the same sentence.
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FAQ

FREQUENTLY ASKED QUESTIONS.

Roof cleaning attracts more misinformation than any other exterior service, so these answers stick closely to what roofing manufacturers themselves publish. The short version is that gentle wins.

    Is it a good idea to pressure wash a roof?

    No. Roofing manufacturers state plainly that a power washer causes granule loss and can lead to premature failure of the whole roof system. Low-pressure soft washing achieves the same appearance without taking anything off the surface of the shingle.


    What causes black streaks on roof shingles?

    A cyanobacteria that feeds on the limestone filler in asphalt shingles. It spreads downward with rainfall, which is why the streaks always run toward the eave and appear worst on the shaded planes that stay damp the longest.


    Does algae actually damage shingles?

    Roofing manufacturers say there is no scientific evidence that algae harms asphalt shingles, so the case for removing it is appearance. Moss is a different matter entirely and does cause genuine physical damage by lifting the shingle edges.


    What is the best way to remove moss from a roof?

    Treat it chemically and let it die back and weather off, rather than scraping or brushing. Physical removal takes granules with the moss, and a pressure washer does considerably more harm to the roof than the moss ever did.


    How long does roof soft washing last?

    Commonly a few years, though it varies widely with shade, tree cover, and how much sun the plane gets. Manufacturers are clear that any cleaning is temporary and that the discoloration can eventually come back on its own.


    Will roof cleaning void my shingle warranty?

    Warranties cover manufacturing defects, not damage caused by improper maintenance, so the risk lies in the method. Metro Mobile Pressure Washing soft washes every roof in Fort Washington, MD for exactly that reason, and never any other way.


    What is the best time of year to clean a roof?

    Mild, dry weather in spring or fall, when the solution can dwell without evaporating too quickly and there is no rain forecast for the day. Extreme heat and freezing conditions both work against the treatment doing its job.


    What do professionals use to soft wash a roof?

    A diluted sodium hypochlorite solution with surfactants that help it cling to a sloped surface. Metro Mobile Pressure Washing follows published roofing guidance on dwell time and gentle rinsing on every roof we treat across Fort Washington, MD.

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    HOW WE WORK

    FROM RIDGE TO GUTTER LINE, HERE IS HOW.

    STEP 01

    Assess the roof from the ground
    We identify the material, the age, the growth, and the condition before anyone goes near it. A roof with lifting shingles or failed flashing needs a roofer first, and we will say so rather than proceed.

    STEP 02

    Protect everything below
    Beds, shrubs, and lawn around the perimeter get soaked with clean water. Downspout outlets get attention too, since everything rinsed off the roof arrives at ground level within a few minutes of the rinse.

    STEP 03

    Apply the solution at low pressure
    The mix goes on gently and evenly across each plane, worked in sections so nothing dries before it has done its job. Pressure at this stage is closer to a garden hose than a machine.

    STEP 04

    Let it dwell and watch it work
    The solution is given the time published guidance calls for, and the streaking visibly begins to lift while it sits. Heat and sun both shorten that window, so the surface gets watched rather than timed.

    STEP 05

    Rinse gently and thoroughly
    Clean water carries the treatment down the plane at low pressure, following the natural direction of drainage. Gutters get flushed at the same time, since everything removed from the roof ends up in them.

    STEP 06

    Rinse below and inspect
    Landscaping gets a second thorough rinse, walkways and the driveway get washed down, and we walk the perimeter with you to look at each plane from the ground, where the difference is most obvious.
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    GET YOUR FREE ESTIMATE

    FIND OUT WHAT IS GROWING ON YOUR ROOF, FREE.

    We will look at each plane, tell you whether you are dealing with algae or moss, and explain what each one means for the roof. Written figure, no obligation. Start on the contact page and we will come out.
    WHAT YOUR FREE ROOF ASSESSMENT COVERS:
    • Each plane assessed for algae and moss
    • A plain answer on cosmetic versus structural
    • The exact method we would use, and why
    • Any lifting shingles or flashing we notice
    • Landscaping protection explained beforehand
    • A written figure with no obligation