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Outdoor crawlspace insulation question


DKG's Avatar
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Join Date: Apr 2002
Posts: 26

03-17-03, 08:41 AM   #1  
Outdoor crawlspace insulation question

Several posts ago I asked a question about insulating a crawlspace and received several helpful replies. I think I now know how to proceed on that part of the crawspace (the part under the house, contained within the cinder block foundation)

Now for the second part - I have a room addition that is supported by posts and is not contained within the cinder block foundation. Thus, the underside of that room is exposed to the outdoors on 2 sides, except for some decorative lattice work around the exterior. It looks like the underside of an outdoor deck. Do I insulate this outdoor crawlspace the same way as I would a traditional crawlspace that is inside the block wall (i.e. using rolled insulation with the vapor barrier facing upward)? Is there any reason to put down a black plastic vapor barrier on the ground underneath?

Thanks!
David

 
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Mike Swearingen's Avatar
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Join Date: Dec 1999
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03-17-03, 09:02 AM   #2  
Yes, insulate the floor just as you do over an enclosed crawlspace.
There is no need to put down a vapor barrier as it is well ventilated.
Good Luck!
Mike

 
Ed Imeduc's Avatar
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Join Date: Aug 2002
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03-17-03, 12:52 PM   #3  
floor joist

You say two sides open here. For sure put the paper side up to the floor and I would also put a 1/2" wire mesh on the bottom of the joist. There is just all kind of things that like to get up there and live in the insulation. When doing a room like this over an open space. After the joist are down we put a 2 mil poly over them and then lay the 3/4 TG down for the floor. This way we have a good vapor seal on top of the insulation. WE do not insulate the floor joist at all that are over a crawl way just on the sill plate in the joist space. The walls with 2" polystyrene and 4 to 6 mil poly on the ground ED

 
DKG's Avatar
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03-18-03, 08:13 AM   #4  
Thanks so much

Thanks Oldguy and Ed for your thoughts. I am replacing the existing insulation with new insulation because critters have gotten inside it and shredded it. Also, when it was originally installed someone put Tyvek foil sheathing on the bottom of the joists, thus sandwiching the FG insulation between the floor above and the Tyvek below. I don't know if they were trying to keep out moisture or critters, but the critters just chewed holes through the Tivek and nested in the insulation on top of the Tyvek. Hopefully the 1/2 inch wire mesh and removing the Tyvek will be somewhat of a deterrent.

Thanks again
David

 
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