I have been going through my past issues, and I noticed an excelletn article by Joe Lstibruk, in which he noted what a bad idea it is to put insulation between the floor and crawl space in most of the US, for condensation reasons. Then in another FH issue, I saw a response to a question written in showing how to insulate a floor over crawl space. Why would FH show someone how to do something they shouldn’t do?
It would be nice if we had an agreed upon orthodoxy on this fundamental point.
Any comments?
Replies
There are two different camps when it comes to crawlspaces. One camp says to insulate the floor and put vents in. The other camp says to seal the crawlspace and insulate the perimeter.
Both camps claim that their way is superior to the other. Not surprising that FHB would have stuff from both camps.
jt8
"All the knowledge I possess everyone else can acquire, but my heart is all my own." -- Goethe
Which camp are you in? I have great respect for Lstibruk's opinion.
My house is in a dry climate area with winter snow and very low temperatures, and the floor insulation over my crawl space has not produced any visible problems, and the house is not new.
I think it depends critically on the climate you're in.
I'm currently leaning towards the seal it and insulate it camp, which is what I'm doing to the current project house, but I don't claim to know which group is correct.
jt8
"All the knowledge I possess everyone else can acquire, but my heart is all my own." -- Goethe
Sealing it can mean sealing off the wet ground under the house is some cases.
How are your local building officials about not having vents?
I have some small windows that will fit the vent holes (once I've ground them out a little). So in theory I'm still following code, because the vents are still there and could be opened. I think in the 'sealed crawlspace' articles, they are actually sealing the vents. I'm not sure how they get by the inspectors on that one.
jt8
"Even if I knew that tomorrow the world would go to pieces, I would still plant my apple tree." -- Dr. Martin Luther King, Jr.
Uh-oh. I think I'm unwittingly conducting an experiment on a 3rd option - semi-seal the crawlspace and insulate the floor.I have a crawlspace with no vents. The foundation and dirt floor were covered before I bought the house with this product:
http://www.neutocreteinc.com/index.html. (I'd describe it as a sprayed-on cement product that reminds me of the stuff they make gunnite swimming pools with.)There's an opening that joins the crawlspace to the adjacent basement (also sealed with neutocrete) that's about 2' high X 5' wide. The basement has windows (usually closed but loose), and a vent fan on a timer that exhausts basement air to the outdoors.After that neutocrete stuff was installed I came along and renovated the house. I was having Icynene applied to the unvented cathedral ceiling so I asked them to go into the crawlspace (I'm sure they loved me for that) and insulate the underside of the floor.So now I guess I have the worst of both worlds - an insulated floor over an unvented crawlspace.oy vey.
Bump. Cause I really want to know.