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David Axt, AIA, CCS, CSI
Senior Member
Username: david_axt

Post Number: 293
Registered: 03-2002
Posted on Monday, July 12, 2004 - 07:20 pm:   Edit PostDelete PostPrint Post

I asked this question earlier and did not get any replies. So I will ask it again only LOUDER!

******

There is a concern that TPO roofs do not comply to building codes and have been "cheapened" due to a glut of manufacturers on the market. TPO roofs seems to be falling out of favor with some of the local roofing consultants.

TPO used to be our firm's single ply roof of choice, but now the firm is rethinking it.

Interesting article:
http://www.professionalroofing.net/past/feb02/tech.asp

Any comments or experiences?
John McGrann
Senior Member
Username: jmcgrann

Post Number: 22
Registered: 03-2002
Posted on Tuesday, July 13, 2004 - 08:56 am:   Edit PostDelete PostPrint Post

Although the in-service time has only been 8 to 10 years, I’ve had reasonably good experiences with TPO membranes. Biggest problems have been with some early installations where the installers were not used to the lower welding temperatures and scorched the membrane with the hot air welder, and the typical membrane damage resulting from the activities of service personnel.

Other TPO products have received ICC evaluation reports since the publication of the article in Professional Roofing. Of course code evaluation reports are only one factor of many that are considered in determining which product to specify. The lack of a code evaluation report doesn’t necessarily mean that a particular building product doesn’t comply with code, nor does the evaluation report imply that a particular product is suitable for the intended application.

There are many ways to cook up a roof membrane, and since TPO is the current low-priced commodity sheet there appears to be a lot of experimentation going on with the various recipes. The practice is not unheard of in the roofing industry, and there have been some spectacular failures over the years. Inspections of older roofs haven’t revealed unusual levels of wear or deterioration, however I don’t expect that current membrane formulations produced by some manufacturers are quite the same as the original batch of products.

For me it comes down to how much I trust the roofing system manufacturer. The manufacturers who are honest in their dealings and work to earn and maintain my trust see their names in print in my specifications. Everyone else sees the phrase “no substitutions”.
David Axt, AIA, CCS, CSI
Senior Member
Username: david_axt

Post Number: 294
Registered: 03-2002
Posted on Tuesday, July 13, 2004 - 01:10 pm:   Edit PostDelete PostPrint Post

I researched the new 2003 International Buidling Code. The code does not mention TPO roofing materials.

Section 1507.12.2 refers to Thermoset Membranes in conformance with ASTM D4637 (reinforced EPDM) and ASTM D5019 (unreinforced EPDM).

Section 1507.13 refers to Thermoplastic Membranes in conformance with ASTM D4434 (PVC).

Does that mean that TPO membranes are not allowed by code?
Ronald L. Geren, RA, CSI, CCS, CCCA
Senior Member
Username: specman

Post Number: 44
Registered: 03-2003
Posted on Tuesday, July 13, 2004 - 01:18 pm:   Edit PostDelete PostPrint Post

No. Section 1506.3 states in part "In the absence of applicable standards or where materials are of questionable suitability, testing by an approved agency shall be required by the building official to determine the character, quality and limitations of application of the materials."

I would also direct your attention to Section 104.11, which refers to Alternative materials, design and methods of construction and equipment. The purpose of the code is not to limit the use of materials. It can't be all inclusive, so some things are not directly prescribed in the code. If the product meets the intent of the code with suitable backup data (testing reports, etc.) then the building official should allow the product.
David Axt, AIA, CCS, CSI
Senior Member
Username: david_axt

Post Number: 296
Registered: 03-2002
Posted on Wednesday, July 14, 2004 - 04:19 pm:   Edit PostDelete PostPrint Post

Thanks Ron!

Further research has found that TPO and KEE will be included in the next 2006 IBC.

http://www.rsimag.com/rsi/article/articleDetail.jsp?id=84133

David Cline
Senior Member
Username: dcline

Post Number: 21
Registered: 03-2002
Posted on Thursday, July 15, 2004 - 06:04 pm:   Edit PostDelete PostPrint Post

As John McGrann pointed out, "Other TPO products have received ICC evaluation reports since the publication of the article in Professional Roofing."

GenFlex's ICC ES Report# for TPO is ER-6092.
Take a look a Peel-n-Stick TPO by GenFlex.

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