It’s not uncommon for water to collect on a roof during heavy storms. If it’s raining hard enough, the water may have to sit on a roof for an extended amount of time if gutters become overloaded. However, if water collects and sits on the roof of a home long enough, the structural integrity of a home may be threatened. Water that has been on a roof for at least 48 hours is called standing water and can cause serious damage to the home’s structures; homeowners should notify Madison roofing professionals if this occurs on their roof.
Two of the major issues associated with standing water include its weight and the fact that roofs are designed to dispel flowing water. Roofs are installed on an incline, and even flat roofs aren’t completely flat, so that water is compelled by gravity to keep moving.
The majority of roofs have asphalt shingles, which are hydrophobic, so they actually repel water and direct toward the gutter. Gutters then send water to the downspout, which deposits water away from the home. Weatherproofing and underlayments, which are tar paper sheets than can be installed underneath shingles as an additional layer of water protection, can help. However, they are mostly for filling gaps in between shingles.
They are not able to keep standing water out.
When water sits on a roof, it will not only start working its way between shingles but through them. This is due to the fact that shingles have tiny imperfections. If water is flowing, this isn’t a problem, but when it sits, leaks may become more likely.
Along with potentially increasing the chances of leaks, standing water can also add an enormous burden to a roof. Water is heavy, even in fairly small amounts. An inch of water spread over a five by five foot square area weighs 250 pounds. This much weight on a roof is likely to create a depression, which creates more space for water to collect, further adding a burden of weight to the roof and possibly making the depression larger.
Roofs have a load bearing capacity, which is the amount of weight that they can safely support. Enough standing water can actually exceed the roof’s load bearing capacity. This is even more likely if people have other things on their roof, like air conditioners, solar panels or satellite dishes. If a roof cannot support a specific amount of pressure, it could collapse.