Flat Roof House Snow

The r value or resistance to heat flow for snow is about r 1 per inch.

Flat roof house snow. 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. 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. This image depicts another benefit of flat roofs. 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.

They can be extremely low. 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. This image depicts another benefit of flat roofs. There are a few common misconceptions regarding flat roofs that are stubbornly persistent.

Neither of these are accurate. Since snow falls at slow steady speeds large quantities of snow can fall on the roof resulting in bowing. 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. 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.

Excessive rain heavy snow and built up ice all pose extra challenges for flat roofed homes. 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. This down bearing pressure can cause the roof to bow and result in ponding under the roof structure.

Snow and your flat roof. They can be extremely low. One of them is that flat roofs leak more easily than pitched ones. As snow falls it can accumulate on your flat roof putting unnecessary weight on the structure.

Another is that they cannot handle as much snow weight as pitched roofs because the snow sits directly on the roof. With a flat roof you don t have the typical attic space afforded by a sloped roof.