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Brian Bothun
Posted: Sep 12, 2011 03:56 PM
Scarfing and priming
I'm bidding on a roof that had foam and coatings applied 25 years ago and has not been touched since. The building does not leak but there is exposed foam. I've gone round and checked depth and it is 1" of foam. I'm planning on scarfing a half inch off and applying 1.5" back on and coating..

Question: Am I going to need to prime the scarfed foam prior to spraying the new foam?

(I'm subbing the foam portion to a roofer)
Dennis Davidson
Posted: Sep 13, 2011 08:36 PM
Yes! Always prime any foam that has been scarfed after you thoroughly clean the remaining foam...lots of dust and foam chips.

If there is only one inch of foam and your planning to remove 1/2 there won't be enough left to support your new roof system. The success of the new roof is relying completely on the remaining 1/2" of old foam. For all the effort and expense you'll put into scarfing and cleaning and priming, you may as well remove everything and start over. At least you'll know the adhesion is good throughout the entire new roof system. Personally I won't scarf a roof with less than 1 1/2" foam.
Have you done very many roofs before? Even if your subbing the foam out you need to know if they are doing it right. It's your job and you are responsible for the success or failure.
Brian Bothun
Posted: Sep 14, 2011 02:56 PM
When I get these jobs I do all the prep work and coatings. Sub out the foam part. The guys I work with are very good at what they do. I was unable to get ahold of them that day was the reason I turned here to try and get my bid finished up.

I haven't scarfed a roof before. Sounds like I should give them a call back to re do my bid to scarf all of the roof.
Dennis Davidson
Posted: Sep 14, 2011 05:36 PM
Sounds like subbing the foam portion is working for you. Teaming up with another company that your confident in is a great way to go. Your doing the most important parts of the job with the prep and coatings anyway. If you don't do your part right then the foam doesn't have a chance.

Before you re-bid the roof, is the existing foam really that bad or is the foam exposed in just a few areas (less than 5% of the roof area)? What type of coating is there now? I specialize in existing foam roof restorations and have saved many foam roofs from the landfill.
Brian Bothun
Posted: Sep 14, 2011 07:20 PM
Send me an email and I will send you some pictures.


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