# durafoam



## Windows on Wash (Aug 30, 2011)

Keep adding rigid foam (XPS) until you get to the desired R-Value at the concrete level. 

I am not sure that durafoam offers any advantages (and perhaps the opposite) over XPS.

Another 2" of XPS, sealed bands, studded wall, and batt insulation would make for a nice wall system.


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## Gary in WA (Mar 11, 2009)

Name of closest large city?

Gary


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## tro876 (Dec 10, 2013)

I live on Regina, Saskatchewan.


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## tro876 (Dec 10, 2013)

In Regina.


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## Gary in WA (Mar 11, 2009)

I checked on the facing and came up empty; http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=4&cad=rja&ved=0CD0QFjAD&url=http%3A%2F%2Fplastifab.com%2Fimages%2Fdurofoam.pdf&ei=eFa2UqzoL9HkoATMyYG4AQ&usg=AFQjCNH15oFylIUMjjYXs_sZ_5rzmHA7lw

This site mentions a foil-facing; http://www.emmersonlumber.com/insulation.html

That facing could be problems of pooling water on the slab behind the framing IF there isn't enough above-grade concrete wall to facilitate drying from the elements, or the concrete wall has water problems (signs) now. Right now any condensation/small leaks may be evaporating away due to basement air currents. Be sure outside drainage/flower beds are slopped away from house, etc. 

Fb above grade and 3' below grade is important. The 3/4" thickness (R-2.83) is minimal and with R-15 (3-1/2") Roxul i9n front; 68*F room air, using your 3 coldest monthly averages; http://www.theweathernetwork.com/forecasts/statistics/cl1030230
of 1.87C = 35*F ----your inside face of closed cell foam would be at 40*F, and the dew-point at only 35% Relative Humidity. Need a dehumidifier to keep it below that or moisture would condense there. Just use thicker foam; eg; *R-10 EPS *(no facer) w. R-15 cavity = 48*F at *49% RH*. Or pile on some more EPS ..... Do you need the frame wall for electrical?

Gary


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## northernlite (Oct 12, 2009)

What WoW and Gary said....Too bad the holmesfanforum shut down, there was lots of good info regarding this specifically for us northern Canadians. I'm in Alberta. Everything I researched told me a minimum 1.5" rigid foam was needed before you can put fiber in the wall cavity. Less than 1.5" left the dew point in the roxul or wall cavity, requiring a vapor barrier on the warm side. But now that you have <1.5" (.75") up on the cold side, you would have a double vapor barrier, trapping condensation within the wall profile. Not good. So you will need to add at least another .75" of foam to your existing .75" before adding fiber insulation. The >1.5" foam will perform as your vapor barrier and the dew point will be within it, or beyond it. The fibre insulation (if it needs to) will dry to the inside. This is really all about where the dew point is at your coldest temps. 
So I think you may have 3 alternatives: 1) bond another min .75 EPS to existing (more is better), 2) ?you might be able to spray a min of .75 foam over what you have, or 3) remove the .75 and build a fiber insulation basement wall.


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## tro876 (Dec 10, 2013)

Ok, this is great info. I am doing a lot of wiring for electrical and audio/video in that room so I definitely need it framed up. So just so I am clear on this, if I go min 1.5" foam board on concrete , then frame and roxul Batts, there will be no need for poly on the warm side? Assuming the EPS is completely sealed up floor to ceiling. And also no issues if I go back and glue . 75 over my existing. 75? Definitely wasting money over doing 1.5 but that's how we learn I guess!


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## northernlite (Oct 12, 2009)

1.5" minimum of rigid foam, properly sealed, in your climate will host the DP or move it beyond and perform as the VB you require. More is better. Do not put another VB on the warm side. You may fill the cavity with roxul if you wish, to get a higher R value. I have seen read some dispute that it's good to mix insulations of late, and some recommendations to go all foam, but it's what i did and lots of others in Canada and it works fine. Getting to R25+ with foam alone would be great but is costly. 
I don't know anything about this Durafoam. I assume it's an EPS, like the white beady stuff, which does not perform as a vapor barrier alone. It's a moisture barrier. With the facing, however, it might be a VB, I suspect that's why it is faced. XPS (pink or blue stuff) is a vapor barrier in itself so it's a superior product for your application, but work with what you've got. Can you bond more foam to the Durafoam? Try it and see, or give the manufacturer a call. Don't be stingy with the glue- especially horizontally- if it bonds. Then frame in front, wire and fill the cavity with roxul. No VB. Drywall. Paint. Watch a movie.


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