If the type of insulation in the structure is more flammable such as polymeric insulations it can affect the amount of slope that the roof can have to achieve a class a rating.
Pvc roofing fire rating.
Pvc roofing membranes have passed fm and ul fire testing and have an unlimited slope approval.
Pvc and fire figure 9 1 estimated relative contribution to total tcdd released into the atmosphere from combustion sources.
Not all buildings are required to have a class a fire rating for their roofs.
The building is an excellent example of a fire breaking out on a flat roof adjacent to other buildings and illustrates well the need to consider the external fire ratings of flat roofs both to protect the inhabitants the penetration of the fire element of the buildings but also the people and property nearby more associated with the spread.
These roofs are difficult to ignite burn slowly do not support combustion and self extinguish when the source of flame is removed.
Fire ratings for roofs are classified as either class a class b class c or are unrated if a roof covering cannot meet the requirements for any of these classifications.
Pvc roofs have passed applicable factory mutual fm and underwriters laboratories ul tests for class a and b roof assemblies for high and low slope roof applications.
Ib roof system s products are specifically engineered for strength and our pvc roofing membranes far surpass the minimum astm standard 200 lbf in.
But if it is required all the above factors are evaluated to give the structure its rating.
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The slope of the test specimen is preselected and since steeper slopes are more of a challenge due to melting material feeding the fire the rating applies to the maximum slope passed.
Pvc roofing membranes have a solid fire resistance rating.
The above statement means that our upvc homeline cladding whilst not suitable for all surfaces such as those requiring a class 0 fire rating it is ideal for domestic applications including house refurbishments and new build applications as it achieves a class 1t surface rating which doesn t mean a lot to the typical homeowner but this rating basically means that our range of upvc cladding will not readily support combustion as it tends to char and fall away.
Not all pvc is built like ib pvc.
Comparing ul class a fire ratings with isocyanurate insulation as the substrate the tpo membrane has a maximum slope of 0 5 inch in 12 the pvc is at a 2 in 12 and the epdm achieves a class a at a 0 5 inch in 12 for unreinforced adhered membranes and 0 75 inch in 12 for reinforced mechanically attached membranes.
Class a is the highest rating offering the highest resistance to fire and unrated is the worst.
Ul and fm ratings are specific to individual roofing membrane manufacturers.
Rating having a minimum typical breaking strength of 332 lbf in.
