DIY Message Boards
Insulating under cabin

This topic can be found at:

Aug 15, 2013, 09:46 PM
Insulating under cabin
I have an old 1 story cabin on a granite fieldstone foundation. The under the cabin, the ground is dirt. In the winter the wood floors in the cabin get very cool and the air comes through the spaces between the hardwood flooring. I have added fiberglass in the floor joist from under the cabin and covered in plastic, but have to replace about every year as the mice and chipmunk nest and pee in it and totally ruin it. I am thinking about using and open cell spray insulation on the entire underneath of the cabin and adding a 4mm+ plastic to the ground.

I am hoping the I can get useful feedback about what I am planning on doing with the spray insulation and ground covering.


This message has been edited. Last edited by: august70,
Aug 15, 2013, 11:05 PM
Sadly, any type of insulation will become critter fodder. The only option would be to skin the underside of the joists after installing new insulation. Even at that, it's very difficult to get a 100% seal that keeps out mice. A mouse can fit through a hole not much larger around than a pencil so any gaps will make an opening. If you have enough room to move around under there then maybe you can install a plywood skin to seal any gaps. Otherwise, they will find any openings.

Of course, there is always the poison, electronic repellants or the old reliable fake rubber snake or two.

Aug 16, 2013, 11:30 PM
Jaybee, would Paul (august70) use pressure treated plywood to skin the underside of the joists?
Aug 17, 2013, 05:43 PM
It would not have to be pressure treated, just painted or sealed. There is no ground contact and the house system provides a roof so that it will not get wet. Any regular plywood will work. I prefer to add lattice strips over all joints and around the perimeter to seal up any tiny openings.

Aug 17, 2013, 08:42 PM
How would blown cellulose insulation do with the mesh used to hold it in place? When they make the insulation they treat it with borate to keep the bugs and mice out of it.

If it were my place I'd look at trying to make the crawlspace a conditioned space by insulating the foundation, covering the floor and then throwing a little heat and/or AC down there depending on the season. Not sure how well it works on an old stone foundation though.

General Disclaimer

Any advice given here is general in nature and is not necessarily valid for your given area. If in doubt check with your local codes enforcement department for what is required when doing electrical, plumbing or structural work on your house. Permits may or may not be required in your area and home owners may not be able to DIY some tasks. I have no way of knowing if you have the skills needed to complete the tasks you are asking about, when in doubt seek professional assistance.

My advice may be worth exactly what you pay me for it. :-) For the record I did not stay in a Holiday Inn Express last night.