Fiberglass insulation that doesn't stay wet or attract mice?

[profdant139]

I'm still getting ready to enclose the underbelly -- a daunting project. I'm using an inch of EPS stryrofoam board, covered underneath with coroplast. I'd rather use 2 inch board, but do not have enough clearance under my water tank.

So I would like to supplement the foam board with some fiberglass batting type of material, stuffed into all of the empty space (especially around the water tank).

But the problem, of course, is that if and when that stuff gets wet, it stays wet. And mice love to nest in it --why not? (I guess they don't get itchy from it, like I do??)

So is there any other similar product that I am overlooking -- something soft and "stuffable," but which does not retain moisture or attract mice?

Thanks in advance for your suggestions!

[magicbus]

I would suggest you go to Home Depot and look for the white plastic encapsulated fiberglass batts. I bought a package for the outside wall of a bathroom rehab on one of our homes and had half left over. I used the rest in a high dampness application where the previous insulation was removed due to mold. Five years later completely dry behind the insulation.

Dave

[jferre9570]

Would Rockwool work?

[fred42]

Ten years ago I used to use Polyester-based insulation. It is itch free and no fiberglass dust to inhale. It does not retain moisture and does not mold. However, SafeTouch was discontinued by Dow in spring 2011 due to poor sales. It was a big hit with DIYers, but most installations are done by those who do not make material buying decisions.

I still find it, but I have to get it as pillows from Walmart. Here is the last job I did with it:

https://www.rv.net/forum/index.cfm/fuseaction/thread/tid/29684694/gotomsg/29685117.cfm#29685117

[agesilaus]

Liquid Nails type cement work fine with foam board, there is a type out now that is quick grab called power grab. Not as fast as spray on adhesive but works well.

[SteveAE]

I assume you know this, but Styrofoam (the white stuff) also absorbs water.....and it takes a very long time to dry out (much longer than spun glass insulation). Of course, if it doesn't get (and stay) wet, you'll probably be fine.
Why not use thicker foam (or multiple pieces) where you have the room and thinner foam under your tanks?
Under my tanks, I used a piece of 1/2" camping mat with a piece of 1/2" plywood underneath to help support the tanks (the plywood is supported with tubular steel that bolted up to the original tank supports).
I also cut lots of small foam pieces with my bandsaw to fit as needed. Glued them in with spray adhesive. Note that most spray adhesives will eat Stroyfoam, but are fine for Blue Board (or similar products designed for below grade use).
Don't forget low point drains to get any water out that will eventually find it's way in.....esp. if you tow when it's raining.
Great project and I suspect you'll find the floors warmer on your toes when done.