Replies

1. GBA Editor
   Martin Holladay | Apr 16, 2013 09:07am | #1

   John,
   Most energy experts advise that it makes more sense to insulate your basement walls rather than your basement ceiling. For more information, see How to Insulate a Basement Wall.

   If your floor joists are full of pipes, wires, and conduits, Roxul is a poor choice to insulate your floor joists. You would be better off using a blown-in-place product (for example, cellulose or blown-in fiberglass), or a layer or two of continuous polyisocyanurate installed on the underside of your floor joists.

2. 
   user-973188 | Apr 16, 2013 10:37am | #2

   Thanks for the response, Martin...

   I've been a lurker here for years, and I have seen the basement article you linked; I'll take another look at it after your advice.

   The house, originally built in 1940 or 1950 (town records can't nail it down) is FAR from air tight, and we don't have the money for a deep energy retro or a tear-down/rebuild. The original owner did a lot of the work themselves, or hired contractors that didn't know what they were doing (back in the '60's or '70's, we can't figure that out either). It's a single floor "ranch" style.

   At any rate, there are tons of holes that cause convection from the basement to the living space above, so I was hoping to limit the flow. At some point we want to re-side the house, and use rigid exterior insulation in the process to make a nice envelope, but that's FAR down the line due, again, to limited funds.

   The house is on a granite rock formation, and portions of the basement butt up directly with the granite (& some granite actually intrudes into the basement).

   I was considering Roxul since it's composition would deter the field mice we have in our area (we're on a 2 acre wooded lot). Right now they use the empty floor joists as passage ways, as the original owner "finished" the basement by using layers of drywall to close off the joists from the basement. WHile we've cut down thier entry by using the usual tricks (steel wool in holes, etc.) mouse traps can only do so much, and I was hoping to head them off at the pass, so to speak.

   Keeping our furry friends in mind, would a polyiso panel be something they could chew or burrow through? Or would a panel of Roxul Comfortboard be a comparable alternative?

   Thanks again!

3. GBA Editor
   Martin Holladay | Apr 16, 2013 10:41am | #3

   John,
   Mice can chew through almost anything. They can certainly chew holes through polyiso.

   The best way to reduce the mouse population is to engage in air sealing. Keep plugging those holes. An airtight house is a rodent-free house.

   Before you go to bed every night, set out some more traps, baited with peanut butter.

4. 
   user-973188 | Apr 16, 2013 10:55am | #4

   Luckily it's not that bad. It was when we moved in, since the house had been empty for a few years.

   We have a cat, and the mice seem to stay in the basement area (no droppings anywhere in the living space). We have traps and bait boxes placed at points that had signs of heavy traffic over the life of the house, and we're not seeing as much activity.

   I'm going to take your advice and inspect our exterior where it meets the ground to look for holes; it's been a while.

   What you're saying is that best practice is to get the exterior as tight as possible, then deal with insulating?

5. GBA Editor
   Martin Holladay | Apr 16, 2013 11:11am | #5

   John,
   Q. "Best practice is to get the exterior as tight as possible, then deal with insulating?"

   A. Yes, that would be a good approach.

6. 
   user-973188 | Apr 16, 2013 11:16am | #6

   Thanks!