In building terms, there are generally two types of roofs: steep slope and low slope roofs. Most houses in the U.S. have steep slope roofs, although the degree or steepness of the slope can vary. Generally speaking, the steeper the incline of a roof, the less maintenance will be required, as rain water will roll off more easily.
Low pitch roofs can include roofing with only a slight incline or even none at all. Many garages, sheds, storage structures, businesses, and residential apartment buildings have flat slope roofs. It is much easier to install roofing materials on these structures.
In colder and dryer climates, concrete may be all that is required to protect the building against water accumulation and freezing. In warmer climates and areas with more rainfall, tar or tar paper can be used to cover the roof. Gravel is then spread over the surface to help reflect the sunlight and keep the inside temperatures lower. Bitumen, pitch, asphalt, and coal tar are materials also used in the construction of low slope roofing.
Materials, Labors & Lifespans of A Low Slope Roof
Perhaps the main reason that builders choose low pitched roofs for their buildings is cost. Money is a deciding factor in almost every decision that goes into the design, construction, and future maintenance of buildings. Flat roofs are easier to install, so they require less materials and less labor. The materials used are also less expensive than the shingles or tiles used in steep slope structures. While the materials will not hold up as well over time, the eventual replacement of the roof can be completed very quickly and more inexpensively.
The primary reason that flat & low pitched roofing does not last as long as roofs with greater pitch, is that water can collect more easily on a flat roof. When water does penetrate, it can be difficult to spot, and leaks may not appear for quite some time after the damage has been done. Many commercial buildings have drainage systems incorporated into their design to help alleviate these problems.
How To Determine A Roof’s Slope / Pitch
The slope or pitch of a structure’s roof is determined by a numerical equation. The pitch is the vertical rise divided by its horizontal span. The slope of a roof expressed in the ratio 2:12 would be a roof that rises two inches vertically for every 12 inches it extends horizontally. Completely flat or low pitch roofing has no pitch.
Determining the slope of a roof varies per the design of the building frame. Flat slope roofing will increase the square footage of the home, whereas a more pitched sloped roof decreases the square footage. If you’ve ever been in an attic room of a house, you’ve witnessed this for yourself.
More Pros & Cons of Varying Roof Slopes
Steep slope roofs generally require less maintenance than flat roofs. They repel water more easily as the steeper incline allows water to flow more quickly down into the gutters.
Flat roofs can trap water and cause roof damage. This collection of rainwater, known as ponding, will wear on the roof and eventually require repair as leakage will occur if left untreated. Neglecting this problem can lead to higher maintenance costs and may require complete replacement of the roof instead of a simple repair.
Flat or low slopes may also start to sag in spots over time as roofing settles. This allows water to pool. The increased weight, combined with the moisture of the water, can gradually damage the integrity of the roof.
Some roofing materials allow for better drainage, while others are more suited for repelling sunlight or retaining heat. Shingles and tiles are usually installed to overlap each other, which will further reduce the chances for water to collect and rot the wood.
To learn more about low slope roofs, contact Texas Star Roofing today.
Image courtesy of: Fraser Mummery