How to insulate a gambrel roof (barn style)

Started by Hap_Smith, January 05, 2006, 05:41:25 PM

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Hap_Smith

 :) Hello to all,
I'm new to this site and actually unsure how it works, guess I'll figure it out. My question to you all is dealing with the sweat that happens on a tin roof. I had build a shop building at my other house. The moisture building up on the tin roof would be a pain in the rear. I plan to build another shop here and a house with the same type of roof system gambrel, so we'll have a loft area for the master bedroom. How is it best to insulate a roof like that, so moisture won't be a problem. Is there a product? Help.
Hap Smith in Missouri :-/
Thanks in advance ;)

jraabe

Condensation on the bottom of a tin roof is usually caused by a lack of a moisture barrier between the bottom of the roofing and the moist warm air of the interior. There may be climates (in the humid SE?) Where this can happen with outside air as the metal cools down faster than the air due to dark sky radiation. In either case I expect the solution is the same - provide a waterproof drainage plane under the metal and/or vent the space top and bottom to pull moist air out.

Here are some details on gambrel roof venting that I posted at the old forum. http://www.countryplans.com/bbs/messages/3704.html (the link mentioned on the main CP page is long gone.)



M.G.Smith Jr.(Guest)

Thanks John ,
The picture makes alot of sense. I got the vapor barrier part, but not quit clear on the vent part. Is there a plactic molding vent on the market? If not I guess I would have to do more research on how to properly vent a roof.
You mention the SE humid, yes we have the problem here in S.E. Missouri, some days 90% humidity,real sticky and hot. Reminds me of how the jungle feels, moisture dripping off things. ;) Thanks again John.
Hap Smith
Semper-FI

Hap Smith

Hi :-[,
Now I know a person should log in before posting. Thanks John.
I first mentioned I was new to this...
Hap ;D

glenn kangiser

Save your bookmark or favorite again after you have logged in, Hap and you will always be logged in when you enter the forum.

There is a  product -plastic that is for ridges - looks like a couple layers of heavy plastic cardboard- works as a screen but vents also.  Most sheeting has a high rib on 12" centers - that could possibly be used as air entrance -may need a screen.
"Always work from the general to the specific." J. Raabe

Glenn's Underground Cabin  http://countryplans.com/smf/index.php?topic=151.0

Please put your area in your sig line so we can assist with location specific answers.


Hap Smith

Thanks Glenn :D,
Times two. I had some mention and is suppose to write with a web site that has what I'm looking for. They are just what you mention ::)
I saw central California, I'm orig. from S.Cal LA County. Left in 1973 when I joined the Corps. Went back from time to time on leave. Miss some of the people and the GOOD weather ;D but do not miss the crime as I was raised in East LA :-/ need I say more?
Later for now and again thanks to you and John for your help, I'm sure I will have more questions as the building gets closer to the start date.
Hap