I am enclosing a side porch on my house. I used R-19 in the walls, high-density R-30 in the cathedral cieling. The porch (now the room!) is about 8'x12', and sits on a concrete slab. There is a crawl spaceunder the slab. The crawl space is about 3' high, and is accessible from about little door (about 16" square) in the basement. The bottom of the crawl space is all dirt. The walls of the crawl space are brick/cinder block.

I am wondering-- DO I need to insulate in the crawl space, and if I do, HOW do I insulate in the crawl space? My plan is to blow insulation, but is there any insulation that I can just blow right on the ground? Or, will I need to try somehow to get the insulation off the ground? Can I just lay down some poly on the dirt? If so, how much, and would I need to secure the poly to the walls? It is a very difficult space to work in, so the simpler the solution, the better.

Thanks!

 

There is only one way to do it . The one that works and the gov said so on it www. Put a 4 or 6 mil poly down on the ground. over lap it 2' and tape the seams. go up the wall 2' with it. Now take 2" or 3" polystyrene and put it on the wall up to the joist. Cut blocks of R19 insulation and put them in the joist space up there on the sill plate all around the home. ED

 

Thanks! A couple of follow-up questions from a novice:

First, what is "polystyrene"? Is that the pink styrofoam-like insulation (about an inch or so thick) that they sell at Home Depot?

Also, when you say "put them in the joist space up there on the sill plate all around the home", what do you mean by "joist space" and "sill plate"? There currently are no joists under the concrete slab, and the slab just sits directly on the brick/cinderblock. Do I build out some kind of shelf with the polystyrene that supports the R-19 blocks? Or do I basically just start stuffing the space with R-19 blocks? once I've laid down the poly?

 

No joist just a slab for get it up there then . The polystyrene is that white board that home depot has its like the cheap ice box is made out of. are what do they have that you can use .

Try look at this www.also ED

http://aboutsavingheat.com/crawlspace.html

 

Thanks again for the feedback.

Okay, so I should forget about putting R-19 on the underside of the slab, and instead I should just (a) lay down the poly like you described before, and (b) use foil-faced insulation blankets like they describe on the web site you pointed me to? I just want to make sure I'm understanding you.

 

You got it. You could use the polystyrene board on the walls it will work just as good for insulation and I think easier. Id try and find a 6 mil poly for the ground if you can. ED