Flat Roof House Snow

This image depicts another benefit of flat roofs.

Flat roof house snow.

This image depicts another benefit of flat roofs. For roofs that are flat and with ground snow loads lower than 20 pounds per square foot the roof snow load is equal to 70 of the product of the exposure thermal and importance factors and the ground snow load. With a flat roof you don t have the typical attic space afforded by a sloped roof. Since snow falls at slow steady speeds large quantities of snow can fall on the roof resulting in bowing.

Without that space heat inside your house can warm up your roof melting any snow that s piled up. They can be extremely low. There are a few common misconceptions regarding flat roofs that are stubbornly persistent. As snow falls it can accumulate on your flat roof putting unnecessary weight on the structure.

Although most flat roofs actually feature a slight pitch they still collect more rain snow and debris than traditional roofs making them a safety liability. Yet for historic modern style buildings like this old house s cambridge tv project flat roofs are at the core of the architecture meant to reflect the broad horizontal lines of the natural landscape. The r value or resistance to heat flow for snow is about r 1 per inch. Neither of these are accurate.

That means 12 inches of snow on a flat roof creates an additional r 12 of insulation that arrives at a time of year when you most need it. When water from that melted snow works its way to the edges of your roof where it isn t as warm and then re freezes it can also form ice dams. Excessive rain heavy snow and built up ice all pose extra challenges for flat roofed homes. Another is that they cannot handle as much snow weight as pitched roofs because the snow sits directly on the roof.

Snow and your flat roof. That means 12 inches of snow on a flat roof creates an additional r 12 of insulation that arrives at a time of year when you most need it. The r value or resistance to heat flow for snow is about r 1 per inch. While not frequent per se the low slope of a flat roof does make it more prone to certain problems particularly when it interacts with the elements.

Flat roofs aren t architecturally logical as rain and snow will shed much more quickly off a sloped roof. One of them is that flat roofs leak more easily than pitched ones.