How to properly install insulation under the floor

[Steve Kulpa]

Greetings, The house I just moved into has a crawlspace and NO insulation between the floor joists. With gas heat as expensive as it is now, I want to install the insulation that SHOULD have been there in the first place.

Does the paper backing on the insulation go up against the underside of the floor, or down, so I'm looking at it has I install it from inside the crawl space?

Also, since the joists are 2x12's, should I get 12" thick insulation?

Thanks - just trying to do it right the first time. steve

[Chub]

paper toward heated space

[Newfie]

Paper goes down. Some come with flaps that allow you to staple the paper onto your joists to hold the insulation in place.

Chub wrote:

[louie]

I think Chub was right - paper towards the living space, which means UP in your case. If you can put 12" of insulation, go for it. If it's a dirt crawlspace, you'll want to put some sort of moisture barrier between the dirt and your house too.

[PipeDown]

Use encapsulated insulation. Plastic bag surrounds whole batt. Can be installed either way and has built in moisture barrior. Less irritating to handle as well.

[Steve Kulpa]

I can put 12" of insulation there, but w/ the paper up (as I gather it should be), that would mean having to push my stapler (and my hand) up through the insulation. do the wire braces you buy and just 'stuff' between the joists work well in this case, or are they more for dryer environments like attics, etc.

also, there is black plastic on the ground inside the crawlspace - so the builder did SOMETHING right.

thanks for all the replies, steve

[Chub]

metal wire hanger things hold it up in-between the joists.

[Chub]

that stuff cost alot more doesn't it?

[Jeff]

I nailed short nails into the joists and strung steel wires between the nails as I put in the insulation. Good to do a little at a time as your arms get tired quickly working overhead.

[Joseph Meehan]

Note: much of that encapsulated insulation is encapsulated only to make handling it easier and it does not have any vapor barrier as the plastic has small holes all over it.

[Joseph Meehan]

Sorry, vapor barrier towards the warm side. Unless you are in Florida or south you put the vapor barrier towards the living area, in this case up. You use the metal wires made to hold the stuff up there for this installation.

[Art]

Paper towards heating surface. Use R30 in most parts of US.

[frog99701]

do you know if they buried the insulation? in alaska we burythat stiff foam insulation under the foundation, sometimes.