Insulating the rim joist in crawlspace

jamesbodellAugust 6, 2008

After applying a vapor retarder on the ground of my crawlspace and installing 2 sumps I am now ready to insulate the rim joists. My crawlspace is only about 2 feet tall, and there are sign's of past insect actvity in the wood in terms of holes and some deteriorated beams. All is well now.

Since the rims are above grade and won't come in contact with ground, do I need to use XPS boards, or can I use a foil faced board? Should I spray an insecticide along the joist before I insulate? What should I use?

My plan is to cut and place 2" foam boards in the cavities and use expanding foam to lock in place. Anyone see a problem with that?

I may remove the insulation between the floor joists. Not 100% sure on that yet.


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Why foam board? Termites live in the ground. Look for mud tunnels on the foundation wall. If you have had previous infestation you should be talking to a professional about how prevention.

    Bookmark   August 6, 2008 at 2:27PM
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I believe foam board and foam spray will make a better seal. It might also hide insect activity.

    Bookmark   August 6, 2008 at 9:59PM
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mightyanvil is correct.

While foam insulation is usually a great way to insulate crawlspaces, building codes prohibit foam insulation from being used underground in areas of known termite activity.

    Bookmark   August 10, 2008 at 11:05PM
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