# Covering over Gypsum, insulation adhesion question.



## rsayler (Feb 15, 2016)

Hello everyone, I have a quick question for everyone. We did a core sample on a flat roof showing the main deck having gypsum substrate on an older building. My question is has anyone else had the opportunity to EPS over a gypsum base before. Secondly, what adhesion system did you use to get your insulation to adhere? Thanks in advance, the forums are excellent.


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## photo_shop (Aug 11, 2016)

Can't talk super intelligently because we don't use a lot of eps here in florida. But polyiso sticks to hard/dry gypsum very well in low rise insulation adhesive. therefore eps probably would too. 

You may reach out to your manufacturer to see if they have a tested/approved assembly using eps over gypsum in low rise adhesive.


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## juan tpo.pvc (Sep 7, 2016)

You should use olybond. On the poly iso. Wich is 2 separate liquids that join together then foam up. And you use a a gun that is like the caulk gun but with two barrel.


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## photo_shop (Aug 11, 2016)

Polyiso can certainly be adhered to gypsum and lowrise foam. However the question was regarding EPS.


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## tetondreams (Feb 1, 2019)

Contact your manufacturer and they should have the answers you need. I recommend a pull test for sure as more Manufacturer’s are fine with low rise foam to gym but they require a pull test. 


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