Rigid insulation under house

[sallyneary]

Much of the insulation under my house has been torn down. It seems very annoying and difficult to replace it by myself, since the batts will not stay put for me while I cover them unless I grow a third hand to use. It seems much easier to slide rigid insulation that could sit on the joists, in the areas without pipes.

People who have replied seem to think the rigid insulation isn't a good idea. Is it just because you are thinking of the pipes that hand down? If the rigid type were in non-pipe areas and the soft type in the pipe areas, would you think it would work then? It seemed to me that it would work as a vapor barrier, insulation, and rodent barrier all in one.
Someone also replied that the underside needs to "breathe," so the rigid type might not be good, but if it needs to breathe, why all the plastic to keep moisture out.
Please, if you reply, could you be clear? A lot of people respond with what is probably great advice if I could figure out what they're saying. I am very new to home repair in general and mobile home issues in particular.

[Greg]

the belly does need to breath, if it is sealed up tight two potental problems come to mind.
First, if there is any moisture between the floor and underbelly the possibility & likelyhood of mold increase as well as the rot potental.
Second, should you have a plumbing leak the water is sealed in the underbelly causing more problems such as #1.
Some here have used rigid foam so I will not say it can't be done, I just would not advise it. I would still use fiberglass insulation, you can use 1x2 support srtips to help hold it place untill you get the belly material up. Greg

[sallyneary]

I still don't understand, though. If some belly boards are plastic, aren't they sealing moisture in too? What is the "vapor barrier" for?

[Greg]

I have never seen a plastic belly board from the factory. The newer type are a plastic weave, not solid plastic.
The vapor barrier that we talk about here is a plastic sheet put down on the ground to help keep moisture from the ground from getting under the home. Greg

[steve]

Another method of installing fiberglass insulation is to use piano wire supports.
They are pieces of wire cut a 1/4" wider than the joist space, Just push them up 1/2" onto the bottom edge of the joist and walla, no need for staples, You can make them from suspended ceiling suspension wire.

[Brenda OH reregister]

I put one by twos up across the joists in the area I had to repair, then I slid/threaded the length insulation above them.

I stapled the paper edges to the joists. having the wood up first made it easier for me to do the repair by myself. I usually would not work under a home by myself, but all of the skirting was off, and folks walking by the home were checking on me, and could see if I stopped moving! lol

I then fastened the belly material to boards at two sides of the wrap.

I was able to attach one board to the joists, go around to other side, then attach the other board, which put the wrap up to the bottom of the home. I freely admit this part was tough to do by myself, I had to hold the board up with my knee, or my foot, while screwing it in to start. good time to hire a helper!

the other edges of the belly wrap I attached with spray glue, although I could have used more boards. they would have been below the wrap, and I would have screwed through them into joists as I could find them.

Brenda (OH)

[Barb P]

Brenda, just for the record, I recently had a professional (okay, he was the pro's helper), fixing my belly wrap, among other things.
I was up in the home and heard the unmistakable 'thump' of a head hitting the metal below.
When I went with an ice pack, to check on him, there he was, with a foot and a knee holding up one end of the belly wrap, while sticking the other end up with his hands.
So even the pros can't do it with only two hands....