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Abstract
Four types of roof leaks occurred at a new school builing in Chevak, Alaska: 1) blowing snow entered the roof through eave vents and then melted; 2) slush and ice in roof valleys caused meltwater to overflow the valley flashing and run into the building; 3) water entered at a roof/wall intersection; and 4) in many areas water entered through gaps in the sloping plywood deck. Sealing the eave vents made it impossible for blowing snow to enter the roof at the eaves. Electric heat tapes eliminated the valley icing problem. Missing flashing was responsible for the roof/wall intersection leaks. The absence of a vapor barrier in the roof was the cause of many leaks. We recommended that the roof be repaired from the exterior by removing component elements down to the plywood deck, installing an adhered continuous vapor barrier and reassembling the roof. An alternative roof cladding of composition shingles was discussed as was conversion to a "cold roof." The roof was repaired and modified following our recommendations, and problems appear to have been solved.
Four types of roof leaks occurred at a new school builing in Chevak, Alaska: 1) blowing snow entered the roof through eave vents and then melted; 2) slush and ice in roof valleys caused meltwater to overflow the valley flashing and run into the building; 3) water entered at a roof/wall intersection; and 4) in many areas water entered through gaps in the sloping plywood deck. Sealing the eave vents made it impossible for blowing snow to enter the roof at the eaves. Electric heat tapes eliminated the valley icing problem. Missing flashing was responsible for the roof/wall intersection leaks. The absence of a vapor barrier in the roof was the cause of many leaks. We recommended that the roof be repaired from the exterior by removing component elements down to the plywood deck, installing an adhered continuous vapor barrier and reassembling the roof. An alternative roof cladding of composition shingles was discussed as was conversion to a "cold roof." The roof was repaired and modified following our recommendations, and problems appear to have been solved.
Date
4/1980
4/1980
Author(s)
Wayne Tobiasson; Philip Johnson
Wayne Tobiasson; Philip Johnson
Page(s)
12
12
Keyword(s)
buildings; condensation; leakage; subarctic regions; snow
buildings; condensation; leakage; subarctic regions; snow