Cutting foam board insulation Q????

[The Paw]

given what you describe, I would pre-cut the widths to one-quarter inch less than the space between the joists and use scrap bits as shims to wedge them in. Then I would run a bead of foam insulation from a spray can down the little gap.

You might still have to do some shaving around places where the joists bend more, but I bet it would be way faster....

[Danaus29]

It would be lots faster. I will try cutting them a smidge narrower. No can do with the spray foam right now, too cold. I did put some screws up to hold one board in place. That worked well as long as the holes were drilled before I put the foam board in place. Even if it's not a tight fit it would be better than the nothing we have now.

19 years in this house, you'd think we could have done this sooner. But the crawlspace has been accessible for only 3 years.

[artificer]

Originally Posted by Danaus29

It would be lots faster. I will try cutting them a smidge narrower. No can do with the spray foam right now, too cold. I did put some screws up to hold one board in place. That worked well as long as the holes were drilled before I put the foam board in place. Even if it's not a tight fit it would be better than the nothing we have now

How cold is too cold? If you warm the can to room temperature, you can dispense it in cold weather. It may take more time to cure, but the expansion of the foam should be fine.

If you are going to foam in place, I suggest cutting the foam board 3/8" -1/2" undersized. If you do that, you can get the Great Stuff nozzle into the crack, and seal the whole side of the rigid foam. If you can't get the nozzle in there, you end up with only a small bead of Great Stuff in the corner.

When I do my foaming, I run two beads of Great Stuff. First is as deep in the crack as I can. Once its fully expanded, I come back and add some more to fill the crack. Don't do a complete side at one time. The expanding foam will push the rigid foam to one side, and you will not have space for the nozzle on the second side. Foam wedges or just alternating side to side (or being really quick) works.

Michael

[Danaus29]

It was below freezing the past couple days. Just barely above freezing now. Too cold to work under there long. I should be down there now instead of lazing around here.

[Danaus29]

Crawlspace insulation project day 3. Out of 18 sections I now have 5 finished. Ds's floor is noticibly warmer close to the south wall. 11 end pieces are in. I still feel a draft in my room but not as much as before. The hardest area to reach is just about complete.