Thread: insulation support

I inspected a house (new construction) today where the under-floor insulation was unfaced fiberglass batts just stuffed between the joists. The only support was friction (except for one batt, which had wire supports). How long is that likely to stay in place? I'm going to note that it needs support. And that the missing piece along the front should be installed. I'm not even getting into the vapor barrier thing; at least it doesn't have that on the bottom.

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If there is enough friction, they might stay there as long as needed. However, its also pretty easy to get under there and install the metal wires that should have been installed in the first place.

The insulation will not stay in place and make contact with the sub-floor over time without being held in place. Wire stays do not hook into the OSB so they are no good for this application; they will pull loose and be on the ground in no time. The insulation should fill the josit bays then twine can be laced 12" o.c. to keep insulation in place.

Mike,
The wire stays go between the floor joists and hold in there just fine (if the joists are spaced properly).
Twine???? seriously???

Jack,
Seriously. The wires do not penetrate the oriented strand board on the sides of the joists. I am under 100's of homes that have had them used with TJI's and can only remember seeing a few that are still in place. With dimensional lumber floor joists the wires do penetrate the wood and stay in place. As I said the best thing we have found to do with the newer TJI's is to use laced twine after filling the joist bay completly that way you aren't compressing the insulation.
Just passing along something that has been tried and found to work.

Great debate..... IMO experience which consists of crawling through +/- 3000 crawl spaces - none of it works

There isn't a system employed yet that keeps in place. I've seen lath strips, metal wire mesh, plastic wire mesh, lots of twine (not many crawls in Texas Jack? ), wire stays and others I can't think of. In the end none of it can stand up to gravity, animals pulling at it, cable TV installers and HIs crawling around.

The most common install these days in my area is the twine route but it's marginal at best.

IMO underfloor insulation in a crawl space is by far the biggest limiting factor in doing a good inspection (and not just if it's falling). You can't inspect for insect damage, most of the framing or for plumbing leaks. And most of the time you can't even get to the problem areas anyway because the crap is all falling down.

Vapor barrier aside, the insulation is also installed poorly. The insulation is crammed between the joists and should be cut to fit without gaps, being compressed, etc. And yes, it should be supported, preferably with vapor barrier.