Comments on: Structural Insulated Panels — An Easier Way to Build an Airtight Home

By: Tom

Tom — Fri, 19 Apr 2013 06:54:16 +0000

As long as you are willing to
As long as you are willing to check out different technologies, I would highly recommend that you look at Superior Walls pre-cast concrete insulated panels. Theirs is a monolithic wall system from the dirt up, eliminating all of those areas for air leaks. As a builder of hurricane resistant homes in North Carolina, it is all that I use. High energy efficiency is a byproduct of the thermal mass and lack of ANY air infiltration/exfiltration through the walls.(none, zip, zero, nil). I also spray closed cell foam under the roof deck and totally seal the attic space. This is done for structural reasons and for keeping all wind-driven water out of the house. I will never build another stick-frame house again.

By: John Ring

John Ring — Fri, 29 Mar 2013 04:16:06 +0000

I, too, built a house with
I, too, built a house with IPS on the walls and ceilings - over 20 years ago - 3400 sq ft including the full walk-out basement. That was 8 years before I heard the term Building Science. But I knew that it made no sense to leak conditioned air to the exterior, and insulation was important. SIPs were OSB on one side, sheet rock on the other. Saved lot on interior finishing! Basement walls ICFs. AC rated at over 1 ton per 1000 sq ft.(Need more SW window shading.)
Never tested the house until recently. Last summer did a blower door test. 1.75 ACH at CFM50. Not bad for someone just using logic, which I now know is Building Science.

By: Allison Bailes

Allison Bailes — Thu, 28 Mar 2013 19:13:29 +0000

Melissa B.
Melissa B.: There are a lot of different ways to connect SIPs to each other and to floors and roofs. I'm not familiar with the furring strip method you're talking about. In the house that I built, the wall panels sat on top of the bottom plates, which were nailed down to the subfloor before we stood a wall section up on top of it. There was no big gap, and we sprayed foam in the pocket before setting the wall on the plate.

I didn't do a cost comparison when I built, but I think ours came out pretty close to what it would have been had we stick-built. Amy Musser and Matthew Vande built a net zero house and spoke about it RESNET this year. They found using SIPs instead of sticks with exterior insulation had a 2400 year payback. You can download the pdf file of their presentation at the RESNET website.

By: Melissa Baldridge

Melissa Baldridge — Thu, 28 Mar 2013 18:20:38 +0000

Thanks for this, Allison. I
Thanks for this, Allison. I'm working on a SIPS home for a Habitat project, and I was blown away with the whole thing. Until I saw that the panels sat on furred 1x2s with gaps in-between. So guess which job I took - air-sealing. And it took FOREVER. Even the architect who designed the house (and was there) did a poor job of air-sealing, so I realized that, being a building-science pro, it was my job to make it right.

That begs my question - WHY do those massive panels sit on furring strips on the sill plate, rather than just directly on the sill? That makes no sense to me.

Also, do you have thoughts on the premium someone pays for SIPS, especially since conventional framing (lumber and time) are basically erased from the equation? 'Love to hear your thoughts on that.

Thanks,
Melissa B.

By: Allison Bailes

Allison Bailes — Thu, 28 Mar 2013 04:14:45 +0000

Green Curmudgeon<
Green Curmudgeon: I'll definitely look for the UM info. Sorry to hear that your on-again/off-again home building plans are off again.

Tapani T.: I like the idea of insulation on the outside of the structure. As Joe Lstiburek puts it, 'Don't eat your sweater.'

Ken B.: Thanks, Ken! I hope so, too. I'm a lot closer to it now than I was 5 years ago.

Eric L.: I know about those houses! I lived in one right across the street from the duck pond for two years. It was a building science nightmare.

By: Eric Lowry

Eric Lowry — Thu, 28 Mar 2013 02:29:31 +0000
There are some wonderful old
There are some wonderful old stone houses at Haverford College that could use your building skills.

By: Tapani Talo

Tapani Talo — Thu, 28 Mar 2013 00:13:40 +0000

Having been part of the team
Having been part of the team that introduced stress skin panels to US,it is nice to see them been adopted over initial ‘cold’ shoulder.
I find that personally I prefer 2×6 wall construction with batt and then add min of R=20 to 30 on the exterior with either stress skin or similar product with good nailer on exterior.
Advantage of 2×12 or 2×10 rood rafters is that one gets R=38 with batt and then on top solid R=30 or so that it is still easy to handle.
BIG R=20 ‘heat mirror’ glass on fixed frames – ventilation with heat recovery air ventilator – and one is free from air conditioning or heating by 90% or more.

By: Green Curmudgeon

Green Curmudgeon — Wed, 27 Mar 2013 23:41:58 +0000
Allison - I like AAC as well
Allison - I like AAC as well, but one thing I have heard about it is that since it absorbs moisture, buildings made with it often require a fair amount of heat to remove accumulated moisture in the wall structure. I don't have enough detailed info on this but Pat Huelman from University of Minnesota seems to be pretty knowledgable on the subject.

Thanks for the shout out on my house. FYI - I've given up on building a new one for the time being and am now only planning to make some minor changes to my existing house.

By: Allison Bailes

Allison Bailes — Wed, 27 Mar 2013 20:31:00 +0000
John P.:
John P.: Yes, the Roxul product that applies would be their ComfortBoard IS (IS for insulated sheathing). You can read about it in Martin Holladay's article at Green Building Advisor.

By: John Poole

John Poole — Wed, 27 Mar 2013 20:21:54 +0000
Allison,

Allison,

When you say "rigid mineral wool" as an insulator on the outside, are you considering something like Roxul Rock Board?

Those seem very similar to SIPS to me, albeit I don't know if they're rigid enough to forego sheathing.

Was just wondering...

~ John