Snow Drift On Gable Roofs

Leeward snow drifts occur when wind blows snow off of a higher elevation roof down onto an adjacent lower roof.

Snow drift on gable roofs.

Snow can either blown from the low side of the roof towards the high side or is blown off the higher area of the roof onto the lower projected side. The gable roof exhibited a slightly higher accumulation coefficient than the flat roof. For the case of a roof step where leeward and windward. The wind causing snow transport and.

Ground snow drift is a 2 hfor more complex geometries a reasonable approach is to match the cross sectional area of the odd shaped drift to that for a roof step with the same fetch and ground load 50 faq 4 odd drift geometries approach used for gable roof drifts in 7 05 area for roof step d for a triangular gable drift with a. Gable roof drifts slope limits there is a range of roof slopes which require gable drifts lower limit is on 12 upper limit is 7 on 12 39 gable drifts upper limit observations by ttea unbalance for 6 on 12 less consistent with max slope of roof step drifts 1v 2h angle of repose of drifted snow 30 40. For gable roofs a rectangular drift surcharge was prescribed and the rectangular shape remained unchanged everywhere along the ridge line. Resulting drift formation was envisioned as perpendicular to the roof step para pet wall or ridgeline.

In snowy regions an accurate prediction of drifting snow loads on gable roofs is essential for structural designs. An analysis of snowdrift patterns and accumulation coefficients which are representative of the depth of snow cover for flat and gable roofs showed that accumulation coefficient decreases in accordance with increases in wind speed. Current provisions of snow load in load standards codes are primarily based on limited case histories and engineering judgment.