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Underside Galvanized metal roof Post New Topic | Post Reply
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Chris Hernandez
Posted: Aug 08, 2008 03:51 PM
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Underside Galvanized metal roof
Hi all,I been working in residential for some time but this is my first commercial project and my first metal roof, I would like the comments from the more experienced people Location: Central Florida (Very hot and very humid climate) Builder wants R-11 spray foam applied to the underside of galvanized metal roof, area is 12000 Sq/ft. My estimate is based on an area 50% larger due to the ondulation of the metal roof so my quote is actually for 18000Sq/ft. Any comment on this? Total area could be under-estimated or over-estimated.? I recommended 2” Closed cell to exceed the R-11 requirement. Before spraying I plan on doing a pressure wash with a degreaser and a second pressure wash only with water… will this be enough to get a good adhesion or some primer may be necessary…??? (metal roof is in nice shape meaning no rust) All comments are appreciated… Regards, Chris |
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Posted: Aug 26, 2008 06:49 PM
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Chris, We've done some work similar to your project, and We'll share a suggestion with you since you had little response on the forum. First, get your supplier and or foam rep. involved with what it takes for your foam to form a tight adhesion bond to the roof deck under the temperature and conditions you expect. Follow their guidelines and document your work. Later, this could be important if things don't quite work out right. As far as the bid goes, take a piece of the material and drop a straight edge on it. Check the actual area necessary to maintain the correct thickness. You have to know. Bidding on commercial jobs to allow for unforseen problems is fine, but you need to know the actual amount. A job this size could be lost to a rival because he knew the percentage would be less. Set an acceptable window of nominal thickness and keep the application within that window. The undulation and consistant overage will eat up a lot of foam quick. On commercial work, always check for restrictions or codes which might create additional expense or cause delays. Late in the work or near the end of the work, additional work is often made available after the customer has witnessed first hand the foam. If your cost is monitored, you can do a small "free" token piece of work. Knowing your cost, lets you make an impression that will serve you later. Good luck to you! |
