Consequences of Accumulated Debris on a Roof

Animal Nests

• Piles of debris on the roof look warm and inviting to roaming animals such as roof rats. The animals settle in, occasionally adding to the debris. If any part of your roof has been weakened, they can get into your attic or crawlspace. The animals create more damage by scratching away at the roof or inside the attic. The National Park Service warns that animals, such as rats, can spread disease either through droppings, bites or through infecting bugs which then attack humans.

Mold

• Dank, damp debris left on the roof after rainstorms creates the perfect environment for algae, moss and mold. These substances can spread to your roof materials and eventually into your home, especially if pools of water form as well. These gradually soak into and wear away at the roof.

Wind Threat

• Should a windstorm hit, anything on your roof that isn’t bolted down can go flying. That might not sound so bad if just a few leaves are up there, but piles of debris suddenly flying out into your yard and the street create both a mess and a visibility hazard. A strong wind can blow toys from the roof and cause injury.

Fire Danger

• It’s now common in areas prone to wildfires to require special roofing that won’t ignite as quickly as older styles, but a fire-retardant roof is not much good if it is covered by dry leaves and twigs. Embers from wildfires can travel long distances -- up to a mile, according to Allied Insurance -- and ignite debris on your roof.

Blocked Gutters and Vents

• Leaves not only cover your yard but your roof, too. If enough fall into the gutters, you could end up with blocked, overflowing gutters during and after rainstorms. This Old House notes that this can lead to flooding around your home because the excess water falls right by where the soil meets your home’s exterior. It can lead to mold and foundation problems, too. Also, check all vents around your roof to ensure they are clear; the Wisconsin Department of Health Services warns that blocked plumbing vents can create a backup of sewer gas into your home, which is potentially fatal.