R40 Insulation Value

[electronman1729]

I purchased a whole house fan this year and now it is cooler I want to insulate the opening in the attic. I came across these on the internet, but at $90+ I find this preposterous.

I though of just make my own from materials from Home Depot. Is there such as thing as insulation board with an R value of R-40?

https://www.ecomfort.com/QuietCool-W...AaAgXmEALw_wcB

[SideShow Bob]

Maybe a piece of rigid aluminum backed foam board cut to a little larger than the fan opening and attached from above ? Stack several to get the R value you want.

[Irving]

Apparently R-value multiplies as you stack it together, but you are supposed to use an R-value of 5.6 per every 1" of poly iso. I'm looking at getting some of these tomorrow. I've already been there and they have a LOT of them in I think 3".

https://www.repurposedmaterialsinc.c...so-insulation/

[DFBrews]

Apparently R-value multiplies as you stack it together, but you are supposed to use an R-value of 5.6 per every 1" of poly iso. I'm looking at getting some of these tomorrow. I've already been there and they have a LOT of them in I think 3".

https://www.repurposedmaterialsinc.c...so-insulation/

You have to buy the whole pallet Stu if you want individuals go to extras off 58th And i25

[Irving]

Hmmmm, I didn't ask them at the time. Thanks for the heads up. More than I can spend right now.

[Wolfshoon]

I just used leftover fiberglass insulation blankets from a garage finishing project and taped them together in the shape of a box and put that over the entire house fan assy for the winter. In spring I just lift it off an put it to the side in the attic. This does require access to the attic and fan though.

[Wulf202]

The airflow is more important than the r value in this application. As long as you match the r value of the surrounding area you're fine.

Depending on the application I'd just buy some sheet magnet and cut it to rough shape then blanket it with whatever r value surrounds the area.

[Baetis]

R value is additive. Insulation board will typically have an R-value rating per inch of material. To get to R40 is going to take quite a bit. Polyisocyanurate typically has an R value of 6 per inch thickness. Expanded and extruded polystyrene have typical R values of 3.5-5 respectively. If you use foam board, just make sure you verify what you?re getting.


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