Floor insulation replacement?

'98 Cherokee Classic
4.0L Auto 4x4

So, a couple of weeks ago I drowned my XJ, and got nasty water in the cabin. I did my best to dry it out, but the foam insulation under the carpet wouldn't get dry. So, yesterday I pulled the carpet out. The foam insulation under the carpet was disgusting (dirty, wet, smelly, and deteriorated). So, I tossed the insulation. I spent a lot of time cleaning the carpet itself, and I think I got it pretty clean and dry.

I'm planning on putting the carpet back in today, but I was hoping you guys could recommend something I can use for the insulation? I'd like to find something that is is easy to obtain locally, as I want to get the carpet back in today and don't want to wait for shipping.

Any tips or recommendations would be greatly appreciated!

I used Astroturf in my YJ. I found some that had drain holes in it so it would vent and put it in grass side down. I actually found some in a brown color. It wasn't as quiet as real insulation, but definitely quieter than no insulation. It is bad news to use solid rubber or plastic, anything that restricts evaporation completely will likely rot your floors twice as fast.

Home Depot. You can get carpet pad in a small roll. You don't have to buy 12' goods. Get the anti-mold type. It will have a plastic covering on one side. IIRC, I bought a 6' roll - I forget how long, but it will be plenty to do what you want to do. Less than $10.

kevin s said:

Home Depot. You can get carpet pad in a small roll. You don't have to buy 12' goods. Get the anti-mold type. It will have a plastic covering on one side. IIRC, I bought a 6' roll - I forget how long, but it will be plenty to do what you want to do. Less than $10.

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I saw that, but it looked like it would be too absorbent of water. So, instead I bought duct type insulation. It's like foam with foil on both sides. It's pretty thin (like 1/8"), but I figure I can double it up. I'll post up about how affective it is.

I used rubber mat material from Lowes, cut to fit, into the footwells and for the hump I used the "bubble wrap" looking insulation that has the aluminum foil look to it. After I had all of fitted perfectly I pressure washed my carpet and put it back in over the make shift insulation. Its much quieter/cooler in the cabin and the floor can drain via drain holes under the seats. Mine has been this way for 2 years and the last time I checked the floor pans still looked like new with no rust. The carpet doesn't smell anymore either!

Dynamat...cheaper online but most stores that sell good quality car audio stock it. The stuff with the foil backing is easier to form and sticks better. I put regular Dynamat over a few coats of Herculiner and then the foil backed Dynamat on top, then a new carpet...I guess it works.

Okay, so I ended up getting "Frost King" duct insulation from Home Depot. I used two rolls at about $15 a roll. It's foil on once side, foam, and then adhesive on the other side. It's fairly thin at 1/8" thick, so I put two layers in key areas, and used all of both rolls.

The adhesive didn't stick well at all to the bottom of the carpet (as the stringy pad that was originally wouldn't come off completely). So, I used some foil duct tape, although that didn't stick to well either. Basically, I just had to put the carpet back in the Jeep, then reposition the insulation underneath.

It seems to be working well, I haven't noticed it being any louder or hotter than the original foam. And, best of all the nasty mildew/pond scum smell from the original foam is gone. My jeep smells nice now!

how do you feel it will hold up if it gets wet?

robhurlburt said:

how do you feel it will hold up if it gets wet?

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It's hard to say, the foam certainly isn't as absorbent as the original, but I couldn't really tell if it was "closed cell" or not.

The problem is that even if the foam itself were completely non-absorbent, you'd still run into the problem of the water being under the carpet and/or insulation, where it's going to have trouble evaporating.

If the carpet were touching the bare metal with no insulation, then any water would simply be wicked up and would evaporate. But, if water gets under the insulation, it won't be able to wick because of the foil.

So, drying by evaporation alone would take a very long time. But, if you pulled the drain plugs, I think you'd fair a lot better than with the original insulation, because I doubt it will absorb much water.