Low- slope roofs typically have a minimum slope of one-fourth inch vertical to twelve inch horizontal (¼:12 or 2 percent) depending on the roofing material. Roofs are considered low-slope roofs up to 3:12 pitch.

The short, simple answer is 2:12 has traditionally been considered the absolute minimum acceptable roof slope suitable for asphalt shingles.

Disadvantages of Installing Low-Slope Roofing Systems Water, snow and ice can sit on low-pitched roofs longer than of steep-pitched ones. This can lead to leaks and damage if you do not remove these elements.

Most shingles may be applied on roof slopes of 2:12 to 4:12 (a “low slope” roof), providing that the shingles are adequately sealed against wind lift, and special procedures are followed. In many building codes, allowances are made to permit applications of asphalt shingles to low sloped roofs.

According to the International Building Code, the typical built-up flat roof that uses tar or asphalt goes by the guideline that for every foot (12 inches) of a flat roof, a minimum of ¼ inch must step up or down. This is the basis for calculating the angle, which is approximately a 1.19-degree slope.

Modern low-slope roof or flat roofs tend to use a continuous membrane covering which can better resist pools of standing water. These membranes are applied as continuous sheets, bonded together with heat-welding or adhesives. A more expensive low-slope or flat roof option include sealed metal roofs using copper or tin.

A 2/12 roof slope means your roof has 2 inches of vertical drop for every 12 inches of horizontal distance. Simply put, it’s a shallow roof. That means the roof doesn’t shed water as easily as steeper roofs, which is why choosing the right type of roofing material is so important.

Flat roofs are an ancient form mostly used in arid climates and allow the roof space to be used as a living space or a living roof. Flat roofs, or “low-slope” roofs, are also commonly found on commercial buildings throughout the world.

TPO Membrane Both PVC and TPO are single-ply membrane roof systems designed for low slope roofs. Both systems have hot air welded seams that are strong and durable. A lifespan of 15 to 25 years is what you can expect from a quality TPO membrane roof.

TPO. A relative newcomer to roofing,Thermoplastic Polyolefin (TPO) is a single-ply membrane with many excellent qualities.

Residential low slope roofing can generally be divided up into two broad categories: larger flat roofed applications (low slope) such as residential condominium complexes, row homes, and town houses and smaller applications such as residential porch and garage transitions from the main home where the slope of the roof changes dramatically from steep

Definition of Low Slope Roofing. A “low slope roof” is one that slopes 2″ in 12″ to 4″ in 12″ of run. Because low slope roofs also drain water more slowly than moderate or steep sloped roofs, systems such as slate or asphalt shingles that rely on mechanical drainage for successful performance, are not used.

What is the minimum slope for a clay or concrete tile roof? The International Residential Code (IRC) specifies a minimum 4/12 pitch (4 inches of vertical rise for every 12 inches of horizontal run) for a clay or concrete tile roof, except that a pitch as low as 2-1/2/12 is allowed when two layers of underlayment are applied.