What are SIP's and what do they do? Structural insulated panels, are a wall system that has been used for decades but has the misconception of costing more. If you take the cost of the materials alone, then yes they cost more if you add in the savings for labor and waste then the cost is about even. The panels themselves are comprised of expanded polystyrene insulation with two skins of Norboard laminated to them. Making an incredibly Strong and straight panel system that can be interlocked to create a highly insulated and air tight shell of the house. Let's take a typical stick frame wall system that is used to build virtually every home in this region. (New England) 2" x 6" wall framing with R-19 fiberglass batt insulation. When you factor in the thermal bridging of the wood framing the total R-value of the wall system is reduced to about R-13.7 ( ORNL whole wall calculator) SIP's give you an total wall R-value of about 22.25 nearly double that of a typical home. The other really big factor is the air tightness of the SIP's envelope, something that is essential when constructing a passive solar home.
The process of prefabricating the panels reduces the time spent building the home and reduces labor costs by about 30% if designed properly. Notice I say if designed properly, I cannot stress enough how important proper design is essential to getting it right and reducing costs. One guy I know said he built a home with SIP's and hated it. i asked why and he said that cutting in the windows and doors was a very messy and time consuming process. I couldn't believe it, I had never heard on anyone fabricating the panels in the field. I wouldn't even consider doing this. While sometimes changes need to be made in the field, which is fairly simple, the thought of cutting out all the windows and doors would be daunting if done in the field. The panels we are using come from
Branch River Plastics, a company located in N. Smithfield RI less than 50 miles from the job site and are totally fabricated to exacting dimensions. This makes installing the panels a breeze and virtually eliminates waste in the job site.
No dumpster needed
This is one of my personal goals when building a home. No dumpster! Yes we have some waste but with careful attention to detail this can be dramatically reduced and materials can be chosen that are easily recyclable. On our current project we will not be using a dumpster reducing operating costs even further.
When you combine the reduction in labor and waste, add the increase in insulation value and air tightness, SIP's are one of the best methods to build better homes. While this is just my opinion, it was formed through years of personal experience and research. I spent 18 years building with the old method and the last 10 using alternative materials and have found no other product that can increase your home efficiency without adding significantly to the costs of building better than SIP's.
We are also using the SIP's for the roof of the house increasing the homes efficiency by another 30% of traditional methods. When all of the factors are combined you end up with a home that uses about 40-50% less energy to heat and cool than a traditionally built home. My last project built in Middleboro MA using a SIP's envelope along with passive solar design, efficient heating and cooling, that house heated last winter for only $341, my goal is to make this one even better. We will continue to track this homes performance long after the project is completed, to ensuring that we are reaching our goal of building the most efficient homes possible.
Stay tuned
Tom Pittsley
tom.pittsley@nextsteplivinginc.com
