Tuesday, May 20, 2008

We'll be "SIPping" energy in our new home...


An odd post title, and a really bad pun, but hopefully you'll understand the pun in a few moments. The vast majority of homes in the U.S. are constructed with timber framing, i.e. the traditional stick frame that has regularly spaced wall studs and insulation filling the spaces between the studs. There's a lot of issues with this method of framing homes, most notably the fact that it can take intense labor to frame the home, much of the home must be constructed on site, and insulation is hampered by the fact that thermal loss can travel straight through the studs (I've seen thermal imaging pictures of cold spots in stick-frame walls every 16 inches, or at every stud).

But, there is another option, and after much research, it's the one we're going with: Structurally Insulated Panels (SIP's). SIP's are a sandwich of oriented strand board (OSB, a form of structural chip plywood) and insulating solid foam. The OSB and foam are connected by adhesive, forming a panel. See the example pic below.
The panels are pre-fabricated off site and delivered to the construction site like giant jigsaw puzzle pieces, each piece designed to fit snuggly with the next, and with all of the window openings and electrical wiring chases pre-cut into the panels. The framing crew fits all the panels together to form the envelope of the home.

There are a number of huge benefits to building with SIP's. The two biggest in my opinion are the reduction in time it takes to fully frame and enclose a home (typically around 4 days, which is amazing) and the energy efficiency of a SIP home (typically heating and cooling costs are reduced by 50%, and the cost savings are obviously continuous throughout the life of the home). SIP's generally cost more in materials, but typically make up for that in labor savings due to the reduced framing time. So SIP's, on balance, generally run about equal with conventional stick framing cost (maybe 5% more in total), and then there are significant savings reaped in energy cost throughout the life of the home. Not only that, but SIP's allow easy construction of vaulted ceilings like we're having on our second floor (there's basically no extra cost to a vaulted ceiling), they are very strong, they reduce construction errors as they are almost perfectly straight, and the home is actually quieter. And, no more stud finding, you can hang pictures wherever you want, and even drywall hanging is less costly during home construction. Since SIP's are pre-fabricated off site and delivered, there is also almost no construction waste (quite the opposite of stick-framing).

Here's a link to a very informative 5 minute video on SIP's showing them being assembled: Link

And here's a great PDF brochure explaining all the considerations that must factor in deciding whether to go with SIP's for home construction: Link

There's also a lot of resources to help the architect or builder avoid pitfalls with specifying SIP construction, especially if they've never worked with them before: Link1, Link2, Link3, Link4.

In my opinion, this is the way most homes will be constructed 10 to 20 years from now. SIP's are definitely a trend in architecturally designed homes and environmentally conscious construction, but eventually they should be very widely used. For us, a little SIP's research and planning will pay off in cost savings and an extremely well-constructed home! (Any engineer's dream!)


Isaac Schwoch said...

This might be one of the coolest things I've ever seen. It's amazing that everyone doesn't use this. Maybe contractors don't want people to find out about it, since it will lower their labor profits?

Brendan Koop said...

It's definitely true that it's amazing everyone doesn't do this, it is by far the best building technology I've encountered. However, it's not because contractors care about labor costs. The real barriers to entry are contractor education (they are used to stick-frame building and it's hard to change building techniques when you are used to something, and it requires some education to learn SIP techniques), as well as SIP's having slightly higher up-front cost for the homeowner. Of course it makes no sense to build a stick-frame home just because you will save a few thousand on the front end, and then pay higher heating and cooling bills month after month after month. But no one ever accused the public at large of being logical.