[AC_Hacker]

Originally Posted by Geo NR Gee

What do you expect for R value once you have it complete?

That is the great question.

The older stufff I was buying was rated at 4 to 4.5/in., and this newer stuff I'm buying is rated at 7.8/2" or R-3.9/in. I don't know if they are using different process/materials, or if they were forced to get honest.

So, I'm expecting R-23.4 from the foam in the walls. There will be an extra R-1 for the wood, R0.5 from the sheet rock and maybe an R-1 for the air barriers at the surfaces of the wall, for a total of R-25.9 or so.

Then there is the thermal bridging thing, and with regular studs, I'll lose 18% for and honest R-21.2. My efforts at thermal bridging reduction should up that at least a bit.

It was suggested to me that a 1/2" foam layer on the inside, over the studs will go a long way to reduce thermal bridging. My grand plan is to do an outside wrap too... but that may be in the distant future. I have been purchasing duplex outlets that have screw-adjusters and that gives me the option to add the extra 1/2" foam wrap inside, if I want.

Originally Posted by S-F

Nice!
How are you going to be sealing the EPS?

Great Stuff at all edges... After the foam sets up, I trim it back flush, then I stagger the joints when I do the next layer, and foam and trim, etc.

Originally Posted by S-F

Hopefully if you get a really good seal between each sheet of EPS and all the surrounding lumber the leakiness that board sheathing should be reduced to a minimum.

That is what I am counting on... zero infiltration through the wall.

Doors and windows are a different matter.

Originally Posted by Daox

Very nice. An upgrade from a semi-leaky R15 that likely gets worse as it gets colder out to a nice solid R30 is quite the improvement!

I'm afraid R-30 might be a bit optimistic, but an honest R-21.2 will really help a lot, especially considering that I live in an area with 4,500 annual Heating Degree Days.

So far, even with just 2 walls and the ceiling done this way, the infiltration reduction is quite noticeable, and already, I completely recognize the requirement of a HRV in the project.

Originally Posted by hamsterpower

600sf kit w/ shipping was $698. I sprayed ~3 inches over ~200sf. so 700/200 = $3.50 /sf. I also increased the thickness of the wall to 8 inches. I filled the rest of the cavities with blown in cellulose. I only needed a few bags after what I salvaged during demo. Anyway, I'd guess it was quicker and about the same cost/sf as your project.

Wow! I'm totally impressed with your method. The economics works out pretty good, too.

This project is already underway, and pretty small, but I may use your method as I progress into other rooms.

Thanks for this info.


Thanks all, for the encouragement...

-AC_Hacker