Drainage from roofs

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Series titleCanadian Building Digest; no. 151
Physical description6 p.
SubjectRoofing; roofs; drainage; roofing products; water barriers; Moisture performance
AbstractSteeply sloped roofs, low sloped roofs, flooded roofs and roof terraces discussed. A perfectly flat roof cannot be achieved in normal construction and slopes will inevitably develop owing to structural deflections. It is better to build in slopes to control water on a roof. The practicable minimum for main roof areas is about 1/4 inch per foot, and greater slope is desirable. Where drainage is achieved by a folded plate type of arrangement, crickets should be placed at the intersection of the larger slopes to direct water to the drains. When controlled flow drainage or evaporative cooling are required on roofs, a sloping roof produces a less hazardous condition than a flat roof. For protected membrane type roofs, the principal membrane at the deck below insulation and landscaping should be sloped, continuous and sealed round all penetrations.
Publication date
PublisherDivision of Building Research. National Research Council Canada
AffiliationNRC Institute for Research in Construction; National Research Council Canada
NoteAussi disponible en français : Évacuation des eaux pluviales des couvertures
Peer reviewedNo
NRC number596
NPARC number20329277
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Record identifierd7ff4625-a7b4-4588-b901-303e7b7be802
Record created2012-07-18
Record modified2016-05-09
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