Why Are Roof Shingles Black

Red brick with black shingles is a classic.

Why are roof shingles black.

A dark roof brings in more desired heat from the sun than a light roof. Algae spores are airborne. Black roof shingles do an excellent job of absorbing the heat from the sun each day. This is what makes those unattractive black streaks on your roof.

A dark roof likely raises the temperature inside your home s highest rooms during the warmer months but during the winter the opposite conditions hold true. Dark color roofing can hide any imperfections in your roof and make it all seamlessly blend together. Algae growth may cause discoloration on roofs resulting in brown or black streaks on a rooftop. Although algae can be found on all types of roofing it tends to be most common on asphalt shingles.

As you can imagine absorbing heat during the winter could help you reduce the amount of heat your heating system needs to crank out to keep your home warm. But now this black algae is termed a roof shingle algae because of the annoying discoloration on a asphalt shingle roof. The algae feed on the limestone in shingles. The black streaks running down roofs are actually a hardy algae called gloeocapsa magma.

Today however the addition of special algae resistant granules that help inhibit the growth of blue green algae helps reduce the appearance of harmless but unsightly black streaks. Gloeocapsa has the ability to form a protective darkly pigmented outer coating that shields the algae from damaging uv rays. This can be great if your roof is not a new construction but you are replacing an old roof on your home. Even the thermal energy with cloudy skies gets picked up with this installation.

To help save on energy things like increased attic floor insulation increased attic ventilation roofing materials with above sheathing ventilation radiant barriers light colored roofing and roofing with reflective pigment can be beneficial. The algae will worsen and become more noticeable each year trapping moisture and causing premature shingle aging and granule loss. As the blue green algae accumulate they develop a dark hardened outer coating which results in the black stains you see. Algae growth on asphalt shingles.

Algae may be mistaken for soot dirt or tree droppings most of which typically produce only localized discoloration. List of the pros of black roof shingles. Lighter colored roofing shingles may help keep the home s interior cooler depending on how effective the insulation and ventilation are. Why do shingles get algae.

One in particular is red brick. There are some black metal roofs available with reflective pigment meeting energy star guidelines. The black roof stains are caused by a form of algae that has been around for years typically found in the woods on the north side of trees or on exposed rocks.