Blown-in Cellulose in Basement Walls (CI on foundation)
jadziedzic
| Posted in Energy Efficiency and Durability on
Is blown-in cellulose insulation something that is suitable for use in a basement wall assembly? I have continuous XPS rigid foam insulation (NGX R7.5) adhered to the foundation walls along with 2×4 walls in front of the CI and want the additional insulation between the studs to bring the walls to around R-21. The basement is dry, and we have good drainage around the exterior (foundation drains and gutters (separately) routed to daylight). Is there something more robust (like mineral wool) that can be blown in? I don’t relish the thought of stuffing all those batts into the walls and have already decided against spray foam.
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Replies
Is the continuous XPS on the interior or exterior of the wall?
What led to your decision that you needed an R21 basement walls?
Since the soil on the exterior is over 50° and the basement and the basement will be under 70° the amount of heat transfer will be pretty small and beneficial in the warmer months. Seems like a waste of resources and an ungreen thing to do.
Walta
Building codes for one thing; the state requires R-15 CI or R-19 cavity in a conditioned basement space so it's either 3" of rigid foam or a lesser thickness with some fluffy insulation, and since the space will be conditioned with an ASHP a higher total R value makes sense. Would you prefer I stick with my original thought of 3" of closed-cell spray foam instead?
jazziedzic,
Yes blown cellulose will work. It's not a first choice in an area which may experience flooding at some point, but otherwise will perform fine.
Installing batts isn't that pleasant, but is a quick job. You should be able to do a large basement in a day. If you are DIYing, it's less work and complexity that cellulose. If someone else is doing it, I'd still use mineral wool batts.