Snow Drift On Gable Roofs

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.

Snow drift on gable roofs.

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. 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. For gable roofs a rectangular drift surcharge was prescribed and the rectangular shape remained unchanged everywhere along the ridge line. The gable roof exhibited a slightly higher accumulation coefficient than the flat roof.

Current provisions of snow load in load standards codes are primarily based on limited case histories and engineering judgment. The amount of additional snow load or surcharge depends on the difference in height of the two adjacent roofs and the lengths of roof perpendicular to the drop in height. Resulting drift formation was envisioned as perpendicular to the roof step para pet wall or ridgeline. Leeward snow drifts occur when wind blows snow off of a higher elevation roof down onto an adjacent lower roof.

For the case of a roof step where leeward and windward. The wind causing snow transport and. Gable roof is a typical roof style which is commonly used in many countries.