Installation is important when it comes to putting a single ply roofing system on a building.
Low slope roof live load.
Visit the roof framing page for more information on cutting roof rafters and visit the roof pitch calculator for determining rafter lengths based on rise and run.
Then apply standard asphalt shingles over the membrane.
To do this i use conservative too heavy dead loads and full snow loads regardless of pitch.
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.
Minimum slope for low slope roof systems with any roofing material a slope of at least 1 4 inch per foot is recommended to promote drainage and minimize ponding.
For low slope roofs wind pressures typically have the greatest magnitude at the roof perimeter and corners.
Technically you should use the actual rafter length when adding up the weight of roofing materials.
1 cover the entire surface with a self adhesive flashing membrane such as grace ice water shield there are many equivalent products.
Resilient synthetic rubber membrane widely used on low slope roofing projects for over 50 years in the united states and worldwide.
For a low slope residential roof there are two main options.
Boca also allows you to reduce the snow load for roofs with slopes greater than 30 degrees presumably because snow will slide or blow off steeply pitched roofs.
Therefore a roof designed and installed to a 1 4 in 12 slope deflects downward and needs to be analyzed as a susceptible bay according to asce 7 10.
On a roof with a slope greater than 4 to 12 the live load limit is typically adjusted downward from 20 psf to 15 psf to allow for the relatively greater dead load on the steeper roof.
Other geometric discontinuities may have increased pressures as well especially those at greater height on the structure.
However in my practice i typically use the horizontal run of the roof for both types of load.
And ice reduces a roof s snow load and dries more quickly than a light colored roof.
Self adhesive flashing membrane under the shingles prevents leakage on low slope roofs.
The membrane will outlast the shingles and seal around all nail penetrations.
The 1 4 in 12 design slope is reduced more from live load and long term dead load creep to exacerbate water retention.
Finding the right products for your low slope roof.
Residential low slope roofing can generally be divided up into two broad categories.
For dead loads you are correct.
