Insulating Framing Cavities
user-7230964| Posted inEnergy Efficiency and Durabilityon
I have 4 framing corner cavities measuring 3 1/2 x 1 1/2 in x 9 ft and 4 rafter cavities measuring 3 1/2 x 9 in x 21 ft with nothing in them but air and no access. I assume spray foam is my best/only option for insulating them. Do you have any advice on how to go about it. What size holes to drill, hole spacing and best product to use would be very helpful.
Many Thanks,
Steve
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Replies
I personally have insulates 1.5" wide cavities with blown cellulose with 1.25" holes every 2' to 2.5', using a 1" cone nozzle on the blower hose.
With 3.5" wide cavities it's even possible to insert a dense-packing tube for blown insulation into a single 2" - 2.5" hole.
Got it - Thank You for the reply. Would you recommend against using open cell or closed cell spray foam?
I'd figure that if you can do blown cellulose then that's the way to go. I watched videos of a house build with SIPs that required filling air pockets in roof panels and it looks like it's a bear to work with foam like that: especially administering it blindly. Foam could coagulate and block without hitting bottom, whereas cellulose would fall and fill (with no real need for encouragement). Horizontal fills are likely a bit of a different story. I don't have any real world experience with this, so take it with a grain of salt (I wouldn't hesitate to take Dana's advice).