EPDM Roof Specs | Ask Mason Knowles - SPF Consultant | Spray Foam Technical Questions and Answers | SprayFoam Magazine Q&A Forums

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jason Forrester Posted: Mar 18, 2008 11:21 AM	EPDM Roof Specs Mason, I recently talked to a contractor in GA about applying a SPF system to some of his existing EPDM roofs.I have been tearing off the EPDM and underlayment and then applying the system to roofs and it has been working well.The contractor suggested to save time and labor cost that he would suggest fastening Dens Deck to the existing EPDM and not tearing it off.Would this work or am I asking for trouble?Any specifications would be greatly appreciated regarding this system. Thanks, Finishing Solutions
richard sucher II Posted: Mar 18, 2008 12:07 PM	Have been installing Firestone EPDM roofing systems for the last 25 years and have sprayed foam for more years than that. The reason you are repairing the roofs is because they are leaking. In order for your SPF roof system to work, you must identify presence of moisture and get any wet components out before any foam is sprayed down. If not, the foam will blister and delaminate and eventually fail. Just taking off the rubber and underlayment will not work if the original substrate is wet and left in place. Do not fall into the trap of by-passing proven roofing techniques and short cutting total scope of work such as full tear-offs, deck repairs, etc. Good luck on your projects.
mason Posted: Mar 20, 2008 08:28 AM	I agree with cobb88 on performing a thorough inspection on the existing roof membrane, insulation, roof deck and assembly. (including moisture survey and core cuts, be sure to repair areas in accordance with RCI and/or NRCA guidelines) Once you identify the wet areas and deteriorated deck areas, you can determine if the roof is a total tear-off or if sections can be identified for separate repair. One big problem with EPDM is that it shrinks. I had a recent discussion with Robb Smith over this topic of spraying foam over EPDM. We agreed that if the EPDM is ballasted or fastened that additonal fasteners would be required to make sure the EPDM stayed in place. Fully adhered systems may stay in place, but you would want to check out the edges for movement and shrinkage. Also, EPDM would typically require an adhesive primer for the SPF to bond well. Discuss the prospective application with your supplier and obtain their recommendations. You may wish to spray a small test section to ensure adequate adhesion.
Gerry Wagoner Posted: Mar 27, 2008 06:45 PM	We have done a lot of SPF over EPDM. 1) clean rubber via power wash. 2) Prime with Techno Adhesive 199 primer. 3) Spray down half thickness of foam. 4) Install screws & deck plates at roughly 5 ft². 4a) Install extra fasteners at perimeter if needed. 5) Install final thickness of SPF over fasteners. 6) Coat, or add gravel..whatever... Clean-up and leave.. Have fun, oG
mason Posted: Mar 31, 2008 08:57 AM	Olger, I am curious about your specification for EPDM. What is the purpose of installing half of the SPF first then installing the additional fasteners? Did you try it the other way and run into problems? How many roofs do you have with this type of specification? How long have they been down. I would like to share it with the SPFA Technical Committee if you can provide some documentation.
Gerry Wagoner Posted: Apr 02, 2008 09:55 PM	Hi Mason. We have tried it both ways. Here's our history. I first sprayed over EPDM in 1996, at a Hospital in Dayton (still looks great, incidentally). In `99 I related my findings with Roger Morrison and together we formalized these guidelines. I must have sent Roger 100 pictures as we experimented and refined our procedures. On a ballasted roof, fasteners must be installed about every 3 ft² to hold the rubber down well. When we sprayed 1.5 -2" thickness we tended to see some moderate "lifting" of the membrane as the foam cooled. To remedy this, we sprayed the 2" in two passes. In 99, we decided to install the fasteners after the first lift. This required half the fasteners, AND anchored the new foam roof better. The fasteners, sandwiched between foam lifts were well sealed. This works. Total square footage is.... about 120,000 ft². (Got another one coming up in Cincinnati, soon.) Still working well. I can send you some jpg pictures if you desire. It makes an excellent system, and is more & more useful as 1st & 2nd generation rubber roofs reach their restoration point. Fully adhered roofs may need some fasteners at the perimeter to ensure 60 or 90, but generally little beyond that. We normally slice the base flashings at the parapets, and term them down. This relieves the inevitable shrinkage that EPDM experiences. The foam builds an almost permanent base flashing. I have also sprayed over a couple DuroLast roofs (don't tell them). :) Works just like the EPDM. Slightly fewer fasteners are needed, because the sheet system is well-anchored every 57". If you go to our web page and click "roofing" on the main page, the top banner is all EPDM restoration. Small pics, but the gallery has some larger pictures. Best regards, Gerry

Author

Comments

jason Forrester

Posted: Mar 18, 2008 11:21 AM

EPDM Roof Specs

Mason,
I recently talked to a contractor in GA about applying a SPF system to some of his existing EPDM roofs.I have been tearing off the EPDM and underlayment and then applying the system to roofs and it has been working well.The contractor suggested to save time and labor cost that he would suggest fastening Dens Deck to the existing EPDM and not tearing it off.Would this work or am I asking for trouble?Any specifications would be greatly appreciated regarding this system.

Thanks,
Finishing Solutions

richard sucher II

Posted: Mar 18, 2008 12:07 PM

Have been installing Firestone EPDM roofing systems for the last 25 years and have sprayed foam for more years than that. The reason you are repairing the roofs is because they are leaking. In order for your SPF roof system to work, you must identify presence of moisture and get any wet components out before any foam is sprayed down. If not, the foam will blister and delaminate and eventually fail. Just taking off the rubber and underlayment will not work if the original substrate is wet and left in place. Do not fall into the trap of by-passing proven roofing techniques and short cutting total scope of work such as full tear-offs, deck repairs, etc. Good luck on your projects.

mason

Posted: Mar 20, 2008 08:28 AM

I agree with cobb88 on performing a thorough inspection on the existing roof membrane, insulation, roof deck and assembly. (including moisture survey and core cuts, be sure to repair areas in accordance with RCI and/or NRCA guidelines) Once you identify the wet areas and deteriorated deck areas, you can determine if the roof is a total tear-off or if sections can be identified for separate repair.

One big problem with EPDM is that it shrinks. I had a recent discussion with Robb Smith over this topic of spraying foam over EPDM. We agreed that if the EPDM is ballasted or fastened that additonal fasteners would be required to make sure the EPDM stayed in place. Fully adhered systems may stay in place, but you would want to check out the edges for movement and shrinkage.

Also, EPDM would typically require an adhesive primer for the SPF to bond well. Discuss the prospective application with your supplier and obtain their recommendations. You may wish to spray a small test section to ensure adequate adhesion.

Gerry Wagoner

Posted: Mar 27, 2008 06:45 PM

We have done a lot of SPF over EPDM.
1) clean rubber via power wash.
2) Prime with Techno Adhesive 199 primer.
3) Spray down half thickness of foam.
4) Install screws & deck plates at roughly 5 ft².
4a) Install extra fasteners at perimeter if needed.
5) Install final thickness of SPF over fasteners.
6) Coat, or add gravel..whatever...

Clean-up and leave..

Have fun,

oG

mason

Posted: Mar 31, 2008 08:57 AM

Olger,

I am curious about your specification for EPDM. What is the purpose of installing half of the SPF first then installing the additional fasteners? Did you try it the other way and run into problems? How many roofs do you have with this type of specification? How long have they been down. I would like to share it with the SPFA Technical Committee if you can provide some documentation.

Gerry Wagoner

Posted: Apr 02, 2008 09:55 PM

Hi Mason.

We have tried it both ways. Here's our history. I first sprayed over EPDM in 1996, at a Hospital in Dayton (still looks great, incidentally). In `99 I related my findings with Roger Morrison and together we formalized these guidelines. I must have sent Roger 100 pictures as we experimented and refined our procedures.

On a ballasted roof, fasteners must be installed about every 3 ft² to hold the rubber down well. When we sprayed 1.5 -2" thickness we tended to see some moderate "lifting" of the membrane as the foam cooled. To remedy this, we sprayed the 2" in two passes.

In 99, we decided to install the fasteners after the first lift. This required half the fasteners, AND anchored the new foam roof better. The fasteners, sandwiched between foam lifts were well sealed. This works.

Total square footage is.... about 120,000 ft². (Got another one coming up in Cincinnati, soon.)

Still working well. I can send you some jpg pictures if you desire. It makes an excellent system, and is more & more useful as 1st & 2nd generation rubber roofs reach their restoration point.

Fully adhered roofs may need some fasteners
at the perimeter to ensure 60 or 90, but generally little beyond that.

We normally slice the base flashings at the parapets, and term them down. This relieves the inevitable shrinkage that EPDM experiences. The foam builds an almost permanent base flashing.

I have also sprayed over a couple DuroLast roofs (don't tell them). :) Works just like the EPDM. Slightly fewer fasteners are needed, because the sheet system is well-anchored every 57".

If you go to our web page and click "roofing" on the main page, the top banner is all EPDM restoration. Small pics, but the gallery has some larger pictures.

Best regards,

Gerry

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