COLD WEATHER ROOF (Cont'd)

In cold weather areas and particularly in mountain regions that experience very heavy snowfall, the cold weather roof or vented roof system is recommended. (Figure 27, 28, and Figure 29, 30 on Page 22). The principle of this system is to allow a constant flow of cold air above the insulation but below the roofing material. With other roofing systems, ice buildup along the eaves can be a problem. Heat escapes from the insulation and melts snow which runs down the roof to the cold overhangs where it freezes, causing water to back up and sometimes penetrate the roof systems. A properly installed, vented cold weather roof eliminates this problem. Venting space should be sufficient to allow a free flow of air from eave to roof top.

There are a number of important considerations that influence roof performance in areas of heavy snow fall, particularly mountain regions.

Design, of course, is very important. The steeper the roof the better the performance. Chimneys should be located at the ridge or gable ends away from possible snow pressure on the slopes. Plumbing pipes should be located on inside walls and should be extended between the rafters and vented at the ridge. If this is not practical then plumbing vent pipes should be galvanized iron, well anchored inside the roof. (Plastic vent pipes extending through the roof may be dislodged by sliding snow).

Wide overhangs at the eaves should be avoided as they provide large cold areas for snow and ice build-up. A strip of metal along the eaves helps shed ice quickly. Sliding ice and snow are constant hazards and should be given primary consideration in the total building design. Outside doors should not be located at the bottom of a roof slope. Entrances and all pedestrian traffic areas are better situated beneath the gable ends of the roof.