Letter To The Editor
SPECIAL FEATURE: Fire Testing of Roof Membranes 

Dear Editor:

After reading the above-captioned article, we believe a few points merit clarification: 

• The October 2001 fire testing commissioned by the Midwest Roofing Contractors Association (MRCA) included Built-Up Roofing, Modified Bitumen with granulated cap sheet, PVC, TPO and EPDM roof systems. Although as you have correctly noted, half the specimens tested failed, (bld)all PVC roof systems(end bold) tested passed the spread of flame requirements for a Class A rated system.
• On the basis of these results, the MRCA determined there was no need to further test PVC (and Modified Bitumen) roof systems in the subsequent phases of the test program.
• Testing new and aged roof systems to confirm they maintain their fire resistance ratings over time is an excellent initiative. Roofing contractors rely upon manufacturers to supply products and systems that meet building codes throughout their service life. Fire performance of a roof is a life and safety issue first and foremost, and secondarily, a factor in property protection.
• The fire performance of roof systems (membranes and insulations) may change with normal roof top exposure. Products requiring fire retardant additives to pass initial testing may well lose some of their fire resistance over time. Products with different types of surfacing (e.g. coatings or mineral granules) may require maintenance to maintain their fire rating. Some roof systems such as PVC are inherently fire resistant and can actually improve over time.
• Maybe the fire test methodology is flawed, and if that is indeed the case, it should be addressed quickly. However, it should also be remembered that some systems passed consistently and while others did not.
• As stated previously all PVC roof systems tested passed the original testing. There is no evidence that a non-combustible cover board is needed for mechanically attached PVC roof systems. The evidence would suggest that a non-combustible recovery board is not required for all mechanically-attached systems.

 

We believe your readers should be made aware of these important points.

 

S.P. Graveline, Vice President, Sarnafil Ltd.