Aluminum or steel window screen. lay flat on floor,slide beneath insulation and staple in place. Fold screen up flat on drywall and staple in place,trim off excess.

Hi Klem,

Your suggestion is very interesting (thanks!). You don't think mice can chew though a steel window screen mesh? Also, I'd need to get a staple gun. I had one but donated it to a thrift store because I never used it (bummer).

Strip of masonite, 1/4" plywood or even sheet metal screwed to the studs?

Or, put a piece of baseboard in now!

millworkman,

I've only seen one mouse, which I caught with a trap, and this is the only space I can think it entered from.

HU-867564120,

I've never installed a baseboard. I was going to have a contractor do it along with some other work.