{"id":132,"date":"2014-12-21T03:56:26","date_gmt":"2014-12-21T03:56:26","guid":{"rendered":"http:\/\/foretruss.yorkdigitalsolutions.com\/?p=132"},"modified":"2014-12-21T03:56:26","modified_gmt":"2014-12-21T03:56:26","slug":"the-wind-exposure-factor","status":"publish","type":"post","link":"https:\/\/fore-engineering.ca\/fr\/2014\/12\/the-wind-exposure-factor\/","title":{"rendered":"The Wind Exposure Factor"},"content":{"rendered":"\n\n\n
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\"\"<\/p>\n

The Slope Factor (i.e. Slippery Roof\u00a0Factor)\u00a0\u00a0 <\/span>1995 NBCC 4.1.7.1(5)\u00a0Conditions under which you can assume the roof is\u00a0“Slippery”<\/p>\n<\/div>\n

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a.\u00a0\u00a0\u00a0\u00a0\u00a0 <\/span>the roof surface is “slippery” (i.e. steel, glass) and,<\/p>\n

b.\u00a0\u00a0\u00a0\u00a0\u00a0 <\/span>snow and ice can slide completely<\/span><\/em> off the roof<\/p>\n

\u00a0Conditions under which you cannot assume the roof is\u00a0“Slippery”<\/p>\n

a.\u00a0\u00a0\u00a0\u00a0\u00a0 <\/span>the roof surface is not “slippery” (i.e. not steel nor glass)<\/p>\n

b.\u00a0\u00a0\u00a0\u00a0\u00a0 <\/span>in cases where snow and ice cannot slide completely<\/span><\/em> off the\u00a0roof<\/p>\n

c.\u00a0\u00a0\u00a0\u00a0\u00a0 <\/span>in a valley section of a roof<\/p>\n

d.\u00a0\u00a0\u00a0\u00a0\u00a0 <\/span>in cases where snow slides or melt water drains onto a lower roof\u00a0<\/span><\/p>\n

The sketches below give some examples of which buildings\u00a0qualify as “Slippery” and which do not. The sketches assume that each of the\u00a0roofs is clad with steel and is steep enough to use the slope factor Cs.<\/p>\n<\/div>\n

The entire roof is slippery.
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Both the upper and lower roofs are slippery despite the\u00a0snow accumulation on the lower roof .<\/p>\n

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In both of these examples, the upper slope on the left\u00a0side of the building is slippery. As far as the upper slopes on the right sides\u00a0are concerned, it could be argued that they are not slippery because the snow\u00a0and ice may not be able to slide completely<\/span><\/em> off the roof,\u00a0depending on the distance to the lower roof. The lower slope on the right side\u00a0of the building is not slippery because snow and melted ice will fall from upper\u00a0roof to lower roof except in figure 3(a) where lower roof can be considered\u00a0slippery provided the slope on the lower and upper roofs are the same.<\/p>\n

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FIGURE-(3a) \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 FIGURE-(3b)<\/p>\n<\/div>\n

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In this example, the upper slope on the left side of the building is\u00a0slippery. The upper slope on the right side is not slippery because the snow and\u00a0ice cannot slide completely<\/span><\/em> off the roof. The lower slope on the\u00a0right side of the building is not slippery because snow and melt water drain\u00a0onto them from a higher roof.<\/p>\n

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Both upper slopes are slippery because snow and ice can\u00a0slide completely off the roof. Neither of the two lower slopes is slippery\u00a0because snow and melt water drain onto them from above.<\/p>\n

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In this example, the roof may be considered slippery\u00a0everywhere except in the valleys. The trusses directly below valley framing\u00a0should therefore not be designed using the slippery factor.<\/p>\n

\"\"<\/p>\n<\/div>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>","protected":false},"excerpt":{"rendered":"

The Slope Factor (i.e. Slippery Roof\u00a0Factor)\u00a0\u00a0 1995 NBCC 4.1.7.1(5)\u00a0Conditions under which you can assume the roof is\u00a0“Slippery” a.\u00a0\u00a0\u00a0\u00a0\u00a0 the roof surface is “slippery” (i.e. steel, glass) and, b.\u00a0\u00a0\u00a0\u00a0\u00a0 snow and ice can slide completely off the roof \u00a0Conditions under which you cannot assume the roof is\u00a0“Slippery” a.\u00a0\u00a0\u00a0\u00a0\u00a0 the roof surface[…]<\/p>","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4],"tags":[],"class_list":["post-132","post","type-post","status-publish","format-standard","hentry","category-technical"],"_links":{"self":[{"href":"https:\/\/fore-engineering.ca\/fr\/wp-json\/wp\/v2\/posts\/132","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/fore-engineering.ca\/fr\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/fore-engineering.ca\/fr\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/fore-engineering.ca\/fr\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/fore-engineering.ca\/fr\/wp-json\/wp\/v2\/comments?post=132"}],"version-history":[{"count":1,"href":"https:\/\/fore-engineering.ca\/fr\/wp-json\/wp\/v2\/posts\/132\/revisions"}],"predecessor-version":[{"id":133,"href":"https:\/\/fore-engineering.ca\/fr\/wp-json\/wp\/v2\/posts\/132\/revisions\/133"}],"wp:attachment":[{"href":"https:\/\/fore-engineering.ca\/fr\/wp-json\/wp\/v2\/media?parent=132"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/fore-engineering.ca\/fr\/wp-json\/wp\/v2\/categories?post=132"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/fore-engineering.ca\/fr\/wp-json\/wp\/v2\/tags?post=132"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}