I read with interest your Oct 31, 2008 post of a Platinum LEED construction (http://evstudio.info/2008/10/31/icf-vs-sipthe-debate-continues/) and I am wondering what you finally decided with respect to LEED points in the SIPs versus ICF comparison.

My wife and I are hoping to build a superinsulated home and try for Gold LEED. We've priced out both ICF and SIPs and, of course, SIPs are much more affordable.

I think our architect and our final builder (bids due in soon) would like to know how your superinsulation format worked with LEED.

Thanks,
Duke"

Hi Duke,

Thank you for your interest in the article. Our experience with both SIPs AND ICFs is that they both will result in a very tight thermal envelope, and that is where the LEED points will come in. As far as that is concerned, I would consider them as equals when it comes to the thermal envelope. The energy model that your engineer will need to do in order to get submit for the LEED certification may show the ICFs to perform a bit better overall, mainly because of the thermal mass they bring to the equation. However, because that thermal mass is insulated from the interior space by the interior side of the form, it is far less effective than if it were in the conditioned space. So, again, the SIPs turn out to be a better value for the money, and every bit as tight and superinsulated as the ICF system.

On a related note, be sure to include an HRV (heat recovery ventilation system) in the home when using either SIPs or ICFs as the superinsulated envelope will not “breathe”, and therefore will require mechanical ventilation.

Good luck with your project and feel free to contact us or have your contractor or architect call or e-mail if you or they have any other questions. Thanks!!
-Dean

ICF homes we've done have the feel of a fortress - a very energy efficient fortress. There is absolutely no sound transfer from the outside. You can immediately sense that you're in a more substantial home. And the energy performance that our clients have noticed has been phenomenal. One client who built a 5200 square foot ranch home in Berthoud using ICF is bragging about utility monthly energy costs in the $20's and $30's, not the several hundred dollars you'd spend to heat or cool a conventional home. By the way, his garage is also ICF construction, and its got a heated floor. SIP panels likewise provide some pretty amazing energy performance. And they do go up quick.

Again, the only negative I can say about either product is the cost. The additional cost is not really related to the product itself - but to the trades that have to adjust their thinking when working on a concrete structure, or on a panel built structure. Framers, electricians, plumbers, heating contractors, roofing contractors, truss manufacturers, etc, all have to re-think their approach, their tooling, and the fasteners they use. That adjustment on their part drives up cost.

My perspective for clients is this: If this is a legacy home - one that you intend to occupy for a decade or more - its worth the extra dollars - or alternatively, its worth it to sacrifice square footage for a superior product. Of course, we should all be thinking more long term these days, so that point of view has to be considered as well .

One last thought. Mary and I built our home of 2 by 6's, and we insulated with Icynene expanding foam in the walls. Our exterior walls are R-28, and the effective R value is higher because there are no air leaks, especially at the vulnerable points, like rim joist, or truss to wall connections. Granted, there's more thermal bridging, but our house is amazingly energy efficient, and very, very, very quiet. My point is this, the stepping stone between conventional construction with fiberglass insulation and ICF or SIP construction is a conventionally framed house with spray in foam. I'm confident that this approach would withstand a very detailed scrutiny comparing cost to build, cost to maintain, and cost to heat / cool, and it would prove to be the most sensible approach for the "typical American family" that occupies a home for 7 years.

A concrete wall will still be standing in 500 years, unharmed by termites or anything else. I have seen the testing on wall systems using the tornadoe test (firing a 2x6 at 120 MPH from a canon) and only the ICF wall passed the test with undisputed results.

SIPs still remain "glued together" with what? Probably a little harmful to health issues. I would rather build with SIPS than conventional framing, don't get me wrong.

As far as assembled on site? Blocks like Build Block are shipped assembled, so stack them and away you go. Check it out on http://www.buildblock.com you'll be impressed with the added features.

Either way, good luck!

http://www.jetsongreen.com/2008/09/prefab-is-not-t.html

-Not many "flat-lander" builders know how to build with them, so any efficiencies will be not be reflected in their framing numbers (SIPs appear to be used more in the mountains)

-It's very nice to be able to fully review shop drawings and correct mistakes BEFORE the house is framed. With standard stick-built projects, there is usually no way to review compliance with your drawings until it’s been built (and in some cases it’s too late)

-Electrical in exterior walls - our panels had standard races, but it was still a major pain for the electrician to pull wires, so we paid a premium

-Some jurisdictions may require a structural calculations book submitted as part of the document set

Overall, I think we will use the panels again. The extremely tight construction combined with nearly perfectly plumb walls results IMHO a vastly superior exterior envelope system for your home.

Otherwise the energy benefits are great. I am also in the thinking stages of my next project and am thinking about using SIP for the floor and ceiling wiht Straw bales for walls, but not structural. I would use some type of post for structure.

The greatest benefit of SIP over ICF is how quick you are working inside. My two story SIP took 1.5 days to put up. After that rain or heat was not much of a issue. Also my huge number of windows and doors took less than a day to set as everything "just fit". I had the window/door manufacturer talk directly with the SIP manufacturer for opening sizes.

Another benefit of SIPs is the rigidity of the material. I put some tile down without backer board to see how it held up. Four years later it is still working well. Also I find that I have had no nail popping on the siding since the walls do not seem to move at all, even in the strongest wind.