You may think you know all about low-slope roofs, which is that they are basically flat, like all the cookie cutter houses that you run across in hundreds of neighborhoods throughout the country, but such is not the case. There is a lot more to it than just a plain, old style kind of flat roof.
Defined by Slant
Both a low-slope roof and a steep-slope roof are defined by their slant, and a nearly flat roof, or one that has a slight pitch to it, is not completely flat. No roof can be completely flat, as there has to be some measurement of slope in order for a roof to drain effectively.
Most low-slope roofs have a slope of less than 3 in 12, which means that a roof that rises 3 inches for every foot of run will be defined as one that has a 3 in 12 slope. Slope is conveyed as a ratio, and it stands for an amount of vertical rise for every 12 inches of a horizontal run, which is again expressed as 3:12 or “3 in 12.”
Options
Today’s low-slope roofs are made to resist water accumulation through the use of membrane coverings that are applied in extended or continuous sheets, which are connected together through specialized adhesives or heat processes. Other options with low-slope roofs consist of metal roof selections like copper or tin panels that are sealed and soldered to create a solid system of interlocking panels. Though these options are more expensive, they can be aesthetically pleasing in appearance and stability.
Physical Factors with Low-Slope Roofs
The low-slope traditional roofs of years past have been comprised of a building up of tar and gravel, but this type of roofing is not as effective in its cost, efficiency and effects on the environment, so other solutions have come into play.
A low-slope roof today has to withstand a number of performance factors that include:
- Wind
- Penetrating UV rays
- Freezing and thawing
- Expanding and contracting
- Remaining watertight
If performance standards are going to be met, low-slope roof attachments will have to be explicitly engineered and seamed to endure multiple weather conditions and years of sunlight exposure.
Low-Slope Roof System Types
There are different types of low-slope and flat roof systems that have been used in the past and are still part of low-slope roofing and they include:
Built-Up Roof
- Historically connected and performing roofing type
- Layers of felt roofing material (tar paper)
- Mopped on roof with hot asphalt or bitumen (coal-tar pitch) for build up that is impermeable to water
- Surfaced with a gravel coat that is embedded in another coat of hot bitumen
- Environmental issues as well as cost factors because of fluctuating of crude oil prices
Modified Bitumen
- Historically performing roof type
- Chemically modified asphalt for flexibility
- Fabricated over fiberglass matting or weighty polyester for added strength
- Coordinates well with extended insulation for increased performance
- Flexible and strong
- Wide range of surfacing selections, including cool roofing
- Wide range of methods of application
- Watertight in its design and composition
- Warranties available
- Overall competitiveness in cost
- Can be packaged as a rated system (fire, wind, hail)
Single Ply
- Can be manufactured as an entire membrane and installed as single ply
- Usually heat welded as single ply material through thermoplastic membrane technology
- White in appearance for heat reflection and high Energy Star ratings
- Durable roof seaming through welding process
- Coordinates well with extended insulation for increased performance
- Environmentally friendly from manufacture to installation to disposal
- Fastest growing low-sloped roofing type
- Proven performance
- Wide range of application procedures
- Wide range of top-coating selections, including cool roofing
- Watertight in its design and composition
- Flexible and strong
- Overall competitiveness in cost
- Can be part of a fire rated system
Whether you have questions about low-slope roofing or are interested in it as a roofing alternative, fill out the online contact form and a representative will get back to you with the answers you need.
