Rim joist insulation and air sealing with diagonal 1x subfloor

[EbS-P]

Time has come to insulate my rim joists. I have diagonal 1x subfloor. Some gaps between the subfloor planks that sit on top of the joists are 1/8” others are bigger. I will cut and place foam next to the joists but how do I air seal the small gaps between the subfloor planks. Most are too small for the applicator tip of a can of expanding foam. I took my FLIR camera seeping on a cold day and the cracks were colder. It was hard to say if it was air infiltration.

Is it even with trying?

Thanks

 

[John Galt]

Once the rim joist is insulated and air sealed with the expanding foam, everything is considered interior space and therefore doesn't need to be sealed. I presume you are doing the 2" rigid foam cut to fill the space and spraying canned foam around the edge. The expanding foam will fill in the seams of the subfloor 1x material, you might have to pause for a second when you hit each crack to ensure a good fill. I really like the "Pro Gun" setup because you can adjust the size of the foam bead but it does use a taller can and your space may be limited.

 

[EbS-P]

Once the rim joist is insulated and air sealed with the expanding foam, everything is considered interior space and therefore doesn't need to be sealed. I presume you are doing the 2" rigid foam cut to fill the space and spraying canned foam around the edge. The expanding foam will fill in the seams of the subfloor 1x material, you might have to pause for a second when you hit each crack to ensure a good fill. I really like the "Pro Gun" setup because you can adjust the size of the foam bead but it does use a taller can and your space may be limited.

I wonder if I can crimp/ smash the end of the plastic tube to fit in the crack. If it doesn’t get into the crack I don’t think it much sealing would happen.

 

[peakbagger]

https://aeroseal.com/aerobarrier/

I see this system mentioned frequently on hard to seal buildings.

 

[EbS-P]

https://aeroseal.com/aerobarrier/

I see this system mentioned frequently on hard to seal buildings.

Vaporized caulk. I’ll pass. I’m after low hanging fruit. Seems like the last resort to hit your AHC50 number. Or what you need to do to get some really low number, like less than 1.

 

[John Galt]

Smashing the tube might work, good thought . The new cans come with the improved spout that you can close off and store the can for a few weeks. The regular foam expands enough to fill those cracks even without squishing the tube, just hold for a half a sec in the gaps. You're hitting the low hanging fruit here. Enjoy the adventure and the work. The energy savings will take a few years to ever pay off.

 

[EatenByLimestone]

Cut the tube to an obtuse > shape. Too acute of an angle will spill foam out the top and bottom.