Does anyone have experience with Dr. Energy SuperAttic?
user-978162
| Posted in Energy Efficiency and Durability on
I am considering having rigid foam board attached against the roof rafters (inside the attic). The sheets are attached and everything is caulked and sealed to make the attic within conditioned space. Obviously with this there is a lot of sealing details that have to be done right. I am considering it as an alternative to closed cell foam. I could do it myself with poliso or there is Dr. Energy franchises that do it . They call it SuperAttic. Does anyone have experience using foam sheathing this way or have had a SuperAttic installed?
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Replies
Kyle,
I just read one web page on this approach:
http://www.drenergysaver.com/insulation/attic-insulation/superattic-system.html
The web page set off all of my warning alarms:
1. No mention was made of the R-value achieved by this approach.
2. No mention was made of what type of foil-faced rigid foam is used. It looks like polyiso, but the web page information is obfuscatory rather than explanatory.
3. The foil facing (an extremely common facing for rigid foam) is referred to as "SilverGlo" facing, as if it is a miracle product other than ordinary foil.
I'm always wary of this type of marketing -- it really makes me cringe.
Hi Martin,
Good point on the marketing. I totally agree it lacks a lot of details like you noted on r-value, foam type but also thicknesses, much of a discussion of sealing details such as top plate etc. Yeah there is some marketing about adding magnesium to the foam, which also gives me pause. That said the approach itself is intriguing, might be worth doing it myself. Are you familiar with anyone using this approach with foam board?
Based on the pictures of a crew installing the panels, it looks like they install one 4" thick graphite-infused, foil-faced EPS panel. R-value would be about 17 if I'm right, which is below code-min everywhere and not exactly very impressive. The radiant barrier might add another R-3 but could provide felt effects in excess of this in a very hot climate. If they'd be willing to triple the thickness of the boards and give you 12", then it would be pretty nice (R-50).
Kyle,
The basic problem with this approach is getting enough R-value without reducing the ceiling height so much that the attic becomes unusable.
Although the photos don't show any drywall, most codes would require drywall on the interior side of the rigid foam.
http://www.delmarvadrenergysaver.com/insulation/rigid-foam-insulation.html advertised R-9 for 2 inches, so I would agree with Nate G that it is ~R-4.5 per inch graphite infused EPS insulation.
Neopor Type 1 EPS is rated for exposure, without a fire barrier, up to 4" thick. (reference: http://www.icc-es.org/Reports/pdf_files/ESR-3463.pdf ); I suspect it is not a coincidence that the photos appear to show 4" thick installations.
Kyle,
My son and I did a version of this recently, -on the underside of the rafters of a cathedral ceiling. We used 2" of polyiso, taped it we'll, so the additional R value should be approximately 13 (an assumption based on the r value simply of the panel itself). It was in large part for air sealing, and there is a 12" batt above, and then 3/4" xps and a vent channel. As stated above, the challenge in having all your insulation here would be the depth/thickness needed, all of it below the rafters. Not many house designs could accommodate the 8 or so inches you would likely need, but is possible.