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Spray Foam on existing polyethelene sheeting Post New Topic | Post Reply
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steve
Posted: Jan 15, 2016 06:53 PM
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Spray Foam on existing polyethelene sheeting
Have a vented attic condition which we would like to remove the existing blown fibreglas insulation and provide spray foam. The existing vapour barrier is a 2 mil polyethelene sheet. Can we spray foam directly onto the poly sheeting?
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mason
Posted: Jan 15, 2016 07:04 PM
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I never like to spray to polyethylene sheeting for a number of reasons 1. Plastic acts as a release agent for foam and would not adhere well 2. The plastic is not a good structural support for the foam and will tend to suck down when sprayed against causing voids and gaps against the decking. Remove the plastic and then spray to the drywall. If it is closed cell foam, picture frame the space first then spray in 1 inch lifts and wait till the foam cools before spraying another lift. Had the same application in my house in Reston, VA. Worked just fine. |
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Brett Adams
Posted: Jan 15, 2016 07:10 PM
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As long as the poly sheeting is tight, not "slick" sheeting, and the spray foam adheres to it, it will perform properly. You will need to confirm that it will not cause a void space between the foam and the substrate, which is why it needs to be tight. against the substrate. Also, I would pull a sample section of the sheeting, complete a test spray against it to confirm that it will adhere before starting the job. This should be part of your estimate process, when you are not certain that your foam will adhere to the substrate you are spraying against. Brett Adams 706-453-0596 Spray Foam Systems http://sprayfoamsys.com |
