Prodex Insulation vs 2” Foamular Board
Hello,
I am looking to insulate a number large chalets in Pennsylvania and Tennessee. These are in the coldest parts of the state (4,000 ft elevation in East Tennessee above the Ski Resort/ we saw 7 degrees this winter ) and 3,500 ft elevation in The Poconos where we often see a few below zero nights and frequent the single digits.
I wish to avoid fiberglass batting at all costs (high vacation rental use = doors left open = humidity etc which leads to batting going bad.
We use built in April Aire commercial dehumidifiers (awesome)
I was considering 2” Foamular augmented by the top grade Prodex sold at Insulation4Less.com that touts R 22 (this is their latest product).
I also wish to add Cement Board / Foam siding sold by Clear Creek Siding which touts R8 as neighbors have his and it looks airtight and awesome.
*We did just install alarms to remind renters to close the doors after they have been open longer than 45 seconds.
thoughts?
Thank you,
-Tim
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Replies
Tim,
It sounds like the first part of your question is about how to insulate the attic/ceiling, correct? Can you describe the assembly? I've my doubts about the stated r-value of the Prodex.
It would be helpful to know the ZIP for both locations.
Hey there Steve,
18624 and 37738
The one in 18624 has half of the house with an attic and half of it is vaulted.
The 37738 has no attic but simple 2x6 T&G for the roof with maybe one inch of foam (it is sad).
We wish to insulate the walls and ceilings.
The Clear Creek Siding was pretty impressive as it is far lighter than other cement board siding companies but has a good 1 1/2 inches of foam under the cement.
Basically, we wish to have Low energy bills all around.
So 18624 looks like Carbon County, PA, which is CZ5. And 37738 includes Rhea County, NC, which is CZ4.
For the walls, you should read this article if planning to use exterior foam: https://www.greenbuildingadvisor.com/article/calculating-the-minimum-thickness-of-rigid-foam-sheathing. In CZ5, you need a minimum of r-5 (2x4 framing) or r-7.5 (2x6 framing).
In CZ4, there is no minimum for exterior rigid foam, so you could use the Richmond Ultra. FWIW, I don't see a version with 1.5 inches of foam. The 1/2 inch in the catalog looks like EPS and might be good for about r-2.
In CZ5, you would need to install an additional layer of foam. The thickness would depend on the type of foam as well as how the wall is framed.
There are different strategies for tackling the ceilings/attics, but I suspect that flash and batt might be the easiest to implement. See this article for details: https://www.greenbuildingadvisor.com/article/flash-and-batt-insulation. If the half attic is ventilated (and done correctly), it may be possible to simply air seal and add insulation in that area.
It's great that you are using whole-house dehumidication to manage moisture. Continuing to use them should help to keep your assemblies safe. With these investment properties, you might want to hire local HERS raters to recommend the best approach for each location. (Check out possible RESNET resources at https://www.resnet.us/raters/hers-raters/.)