How to seal bottom edge of rim joist
user-7561031
| Posted in Energy, Heating & Insulation on
Marine Zone 4. I’m in process of sealing and insulating my rim joists. The process is straightforward but I cannot for the life of me seal the bottom edge of the rim joist. I just can’t get my caulk gun in there because the back end of it hits the ceiling (subfloor) and the tip doesn’t get to the bottom corner. I tried an extension tube but all that accomplished was making a big mess.
Should I just forget about it and rely on the rigid foam and canned foam combo for air sealing?
Replies
Squeeze-tube caulk or an air-sealing tape.
If you are insulating the inside of the rim joist with rigid foam it would work fine to seal that with canned foam. I'd apply the canned stuff onto the top edge of the rigid stuff and press it into place against the ceiling. If you cut the rigid a bit small you'll have room to gun some foam in along one edge, or you can shoot for a press fit on both edges. I usually use a 2x4 scrap to drive in the edge if it's fairly close. It spreads the impact more evenly. Working with rigid foam is easiest if you have a clean accurate way to make cuts.
When I did my rim joists last fall (also marine zone) I did not caulk and used 2" rigid foam with a small gap around perimeter filled with canned foam. And I second the "clean accurate way to make cuts" comment- I used a table saw/skilsaw to make all cuts.
Caulked all around my rim joists and the sill plate...use your finger and its all good...sometimes you have to squeeze a big blob out and spread it into the joints sometimes you have to squeeze it onto your finger and then into the joint. Wear a pair of jeans your dont care about and it makes it easier to clean your hands up periodically.