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Dovetail Greene
Dovetail Greene, General Contractor
Category: Home Improvement
Satisfied Customers: 378
Experience:  Licensed Building Contractor & Certified Building Designer
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This question pertains to a business - not home improvement

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This question pertains to a business - not home improvement but I'm sure the concepts are the same. the owner is adding a large cooler room to the premises (18x30feet) and we need to ensure that the vapor barrier is properly installed. I believe that to be on the warm side of the cold room - can you advise how to handle the walls and the ceiling. The walls are typical 2x4 partition walls and the ceiling is the underside or truss rafters.

Good afternoon.

My name's Kel.

You are correct.

Since warm air flows to cold the warm conditioned air on the outside of the cooler warm will seek to migrate into the walls. Without a correctly placed vapor barrier the warm moist air will condense on the insulation and decrease the insulation's performance. There's an increased likelihood of mold.

You have to tell me more about the ceiling detail. You'll get the best performance if you separate the cooler from the larger building. Therefore they'll be something like a roof to the cooler which can be insulated. A vapor barrier will go over the insulation and be on the outside of the cooler.

Make sure to caulk and foam all penetrations.

Have I answered your questions?

Customer: replied 4 years ago.

Everything you say makes perfect sense. Insulating the truss area over the cooler , as well as preventing attic hot air from migrating to the cooler ceiling is difficult unless one would use a layer of solid expandable foam over that area. If not done this way I understand your concept of separation with a separate ceiling for the cooler room.


Thanx; John

You could use something like Thermax between the top of the cooler and the trusses.

Thermax is polyisocyanurate insulation with metal foil on both faces. You could use several layers of the stuff that's around 40mm thick. The foil will act like a vapor barrier.

You could use expanding spray foam. I'd use the closed cell type.

Your size job could use a professional foam contractor.

If you wanted to do it inhouse you could buy a foam kit from

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