Roof stain or lichens or moss caused by trees (C) Daniel Friedman Guide to Identifying Debris as a Cause of Black Stains Roof Surfaces

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How & when to clean off or remove roof debris:

This article explains debris on building roofs as a source of dark stains on the roof surface and possible reduced roof life or actual roof damage.

We provide at Diagnostic Guide to Types of Stains and Staining Materials Found on Roof Surfaces. Causes, cure, and prevention of black stains on roof shingles.

We also illustrate use of gentle sweeping to remove accumulated debris from a rooftop to extend the life of the roof.

This article series tells readers how to identify & explain the most-common causes of black, brown, red, gray, green, or white stains appearing on roof shingles and on other building surfaces. Roof shingle stains are often caused by black algae, bleed-through or extractive bleeding of asphalt, dirt, soot, or organic debris.

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ROOF DEBRIS STAINING - Black & Brown Debris Stains on Asphalt Shingle Roofs

Roof stain or lichens or moss caused by trees (C) Daniel FriedmanDebris staining on roofs produces fairly uniform black or brown staining in areas where due to low-slope or presence of overhanging trees, leaves, or organic debris collects on the roof slope.

Decaying debris may encourage fungal or algal growth (cited above).

Lichens or even thick moss may also grow on such roof areas.

Debris, lichens, or moss on a roof will shorten its life by holding water on the roof surface, preventing drying, and (in cold climates) adding wear and tear on the roof surface by freeze-thaw cycling.

In contrast, debris from an upper roof gutter that spills onto lower roof slopes may result in tan, white, or other stains depending on the metal of the gutter and the length of time that leaves and debris rest in it.

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The decision to permit the upper roof gutter to spill down the lower slope (photo above/left) also risks creating an early wear-area and thus leaks on the lower slope roof.

Remedies for black or brown or gray debris staining on asphalt shingles: As cited above, cleaning off debris (gentle sweeping or washing, watch out for damaging the roof during cleaning), or cutting unnecessary overhanging tree branches may help.

See PROXIMATE CAUSE roof shingle stains for details about these growths on buildings.

See STAIN DIAGNOSIS on ROOFS for the causes and types of stains that occur on building roofs.

There are other sources of roof staining, from cosmetic to harmful to the roof and as we discuss at WHITE ROOF COLOR BENEFITS (live link just below) stains also affect the roof's solar or heat reflectance.

Gentle Sweeping Off of Roof Debris

Sweeping off accumulated hemlock and leaf debris from a Two Harbors MN roof (C) Daniel Friedman

Above I'm about to gently sweep away accumulated hemlock needles and leaves that accumulate on the up-roof side of skylights on the roof of this Two Harbors MN home. What you see is about a decade's worth of accumulated organic waste.

Watch out: Leaving this debris on the roof can risk more than stained shingles. Organic debris on the roof surface holds water, wind-blown soil, and decaying material that can cause early wear and failure of the shingles below, as a result of:

Watch out: this roof was just low-enough in slope that I could walk on it, but even on a low-slope roof the presence of loose debris can act like a coating of ball bearings, sending you skidding and screaming down the roof and onto the rocky Minnesota ground below.

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Ladder safety: climbing onto a debris-strewn roof is dangerous (C) Daniel Friedman

Really? Now for a look at real world conditions: climbing onto this roof placed me smack into an area where there was already an accumulation of hemlock needles just hoping they could send me back down to earth in a hurry. Walk carefully and use your broom!

I took care to stand above the debris and to sweep carefully and gently (so as to avoid damaging the shingles by scouring off mineral granules). I swept down towards the roof eaves, standing always and only in the swept-clean space.



Continue reading at BLACK or GREEN ALGAE STAINS on ROOFS or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.

Or see BLACK ROOF STAIN CAUSES for a complete catalog of roof stain sources & causes


Or see these

Roof Stain Diagnosis, Repair, Prevention Articles

Suggested citation for this web page

DEBRIS STAINS on ROOFS at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


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