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D. Backes Posted: Mar 30, 2009 08:46 PM	corrugated steel roof on freezer Mason, My company is bidding on a small 0 degree cooler building roof approximately 10 squares total. they have a wide rib steel deck with 3" polystyrene panel covered by 1" perlite under builtup. It has completely wetted through and needs a tearoff. We want to spray 4-5 inches of 3lb foam directly onto the panel. Because the panel is ribbed, the foam will reflect that and look like a nitemare. I would span it with plywood or perlite but I would have the empty valleys in the steel deck below. I assume I have to fill the valleys in the deck first in order to avoid condensation buildup. Before we spray we will of course check the deck for rust and any holes, voids etc. What's the best course of action here?
mason Posted: Mar 31, 2009 07:35 AM	First, It would be better to spray foam in the flutes (after treating the metal to prevent or address any rust), then trim it back so it is level. Then install your foam in 1 to 1.5 inch lifts to full thickness and cover with at least 30 dry mils of a impact and abrasion resistant low perm rated coating. (Check with your foam and coating manufacturer for their recommendation). (The vapor retarder goes on the outside of the foam). Check out SPFA's technical doc. AY 110, A Guideline to Insulating Cold Storage Facilities oepration between -10 and 40 degrees F. It has good information on using SPF in freezers. I wrote that document more than 20 years ago and it was the first official document I was involved in with the old Polyurethane Foam Contractors Division of the Society of the Plastics Industry. (now the SPFA)The Technical Committee recruited me for my expertise in cold storage applications.
D. Backes Posted: Mar 31, 2009 10:45 AM	Thanks Mason, So simple, sometimes you can over think things, like I did here.

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D. Backes

Posted: Mar 30, 2009 08:46 PM

corrugated steel roof on freezer

Mason,
My company is bidding on a small 0 degree cooler building roof approximately 10 squares total. they have a wide rib steel deck with 3" polystyrene panel covered by 1" perlite under builtup. It has completely wetted through and needs a tearoff. We want to spray 4-5 inches of 3lb foam directly onto the panel. Because the panel is ribbed, the foam will reflect that and look like a nitemare. I would span it with plywood or perlite but I would have the empty valleys in the steel deck below. I assume I have to fill the valleys in the deck first in order to avoid condensation buildup. Before we spray we will of course check the deck for rust and any holes, voids etc. What's the best course of action here?

mason

Posted: Mar 31, 2009 07:35 AM

First, It would be better to spray foam in the flutes (after treating the metal to prevent or address any rust), then trim it back so it is level. Then install your foam in 1 to 1.5 inch lifts to full thickness and cover with at least 30 dry mils of a impact and abrasion resistant low perm rated coating. (Check with your foam and coating manufacturer for their recommendation). (The vapor retarder goes on the outside of the foam).

Check out SPFA's technical doc. AY 110, A Guideline to Insulating Cold Storage Facilities oepration between -10 and 40 degrees F. It has good information on using SPF in freezers. I wrote that document more than 20 years ago and it was the first official document I was involved in with the old Polyurethane Foam Contractors Division of the Society of the Plastics Industry. (now the SPFA)The Technical Committee recruited me for my expertise in cold storage applications.

D. Backes

Posted: Mar 31, 2009 10:45 AM

Thanks Mason, So simple, sometimes you can over think things, like I did here.

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