The most common issue with roofs is leaking. If water is able to get around and through the shingles and other waterproofing on a roof, it will damage the components below. The result can be a rotting roof deck (the surface the shingles or other roofing is attached to), rot in the framing that holds your home up, or water leaking into the interior of the home and damaging drywall, flooring, furniture, or other items.
While a roof may look relatively simple from a distance, there actually a number of different parts that go into making sure that water that lands on the roof travels off of the roof and down to the ground below. Roofs require different flashing and water barriers for different types of roofs and at different locations on roofs.
Roofs come in a variety of forms. Roofs can be either a steep roof like the typical asphalt shingle roof on a suburban home or a low-slope roof like the flat roof typical for a condominium building or an office building. Even within those two categories, there are many variations among roofs. A steep roof can have a roof covering of metal, tile, asphalt shingle, slate, or another material. A steep roof can also have many different shapes incorporated in its design—hips, valleys, ridges, dormers, sheds, gambrels, chimneys, eaves, and rakes—which complicate the process of keeping water out and moving it down to the ground below.
On a steep roof, one of the more frequent problems is water getting in at changes in the roof’s slope, like where a chimney comes up through the roof or where two roof slopes come together and form a valley. If flashing was not properly installed at those locations, water can get under the roof covering and into the building.
A low-slope roof directs water to drains in the roof and the water then travels down piping to the ground below. A low-slope roof can be covered by a number of different membrane systems and the membrane system can be held on to the roof by fasteners, an adhesive substance, or by the weight of rocks or other material on top of the membrane.
On a low-slope roof, problems arise when the roof does not have enough slope to direct the water to the drains, when the drainage system is not large enough or is clogged, when the membrane system is punctured or torn, when water gets around flashing at the edge of the roof, or when water ponds on top of the roof.