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Structural Insulated Panels (SIPs), for those who have never heard of them are panels which consist of a "sandwich" of an oriented strand board outer skin, a rigid foam core, and another oriented strand board outer skin. Picture a sheet of of foam insulation with sheets of OSB glued to either side. You can see what they look like here and watch a video about how they work here. Basically SIP homes come in panelized kits that are put together like puzzle pieces. The SIPs form the shell of the building (outer walls and roof)-conventional stick framing is used to form interior walls and floors. The SIPs used to make up the roof only need a "post and beam" style structure to hold them up since they are very rigid and strong. I am seriously considering building with these for a number of reasons.
First, the energy savings are pretty impressive. A 6.5" (you can get them thicker) is rated around R-30 depending on the type of foam used, and that's just for the panel-whatever is applied to the outside plus the sheetrock on the inside provides a bit more insulation. The average 2x6 stick framed wall is about R-15. Those are just calculated numbers though. Stick framed walls have what are called "cold bridges"-the studs which bridge the gap between the outer sheathing and the sheetrock on the inside. A lot of heat is lost through these-SIPs do not have them, so in the real world application the insulation factor is even greater compared to stick built. Next, if you watch a little of the video you can see how easily they go together. This is important because we plan to build our own home and constructing the entire dried in shell quickly would be a huge help. I know I sound pretty convinced at this point, but I'm a skeptic at heart, so I'm trying to get some feedback from folks who have actually built a home with these things and any pitfalls, setbacks, or other difficulties. I'm also eager to hear about actual energy savings, and addressing air movement issues since these homes are so tightly constructed.
In case you're curious, we plan on building something similar to this (www.realloghomes.com/floorplans/log_home_plans_pdf/03W0026.pdf - broken link), which may seem odd since its a log home, but the log companies are now making pretty convincing false corners to compliment their log siding, so you really can have an authentic looking log home now without the drafts, leaks, etc...(I know because I grew up in one) I'm also hoping that the energy savings are as good as they claim-we're planning on supplying all heat and domestic hot water through a wood gasification boiler and home built flat plate solar collectors. The energy savings combined with the efficiency of the gasifier and the free heat from the sun should allow us to conserve our woodlot for years to come. So, anyone building with SIPs out there?
I looked into building an addition with SIPS. It was not cost effective. For a whole building the longterm payback might be worth it. I like SOLID buildings and the SIPS concerns me a bit when it comes to structural integrity. If one is in a large city , great, but rural contractors aren't likely to work with SIPS. I ended up wrapping my existing concrete structure with P2000 foam board insulation on the exterior and then wrapping/siding over that.
Aside from all the benefits, this is the largest "drawback". There are few general contractors with extensive experience with SIPS. And those that do- seem to be concentrated in certain areas of the country. Generally, within a certain radius of manufacturers. Shipping panels half way across the country is not fiscally sane.
Location: Central Atlantic Region, though consults worldwide
266 posts, read 449,910 times
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Quote:
Originally Posted by K'ledgeBldr
Aside from all the benefits, this is the largest "drawback". There are few general contractors with extensive experience with SIPS. And those that do- seem to be concentrated in certain areas of the country. Generally, within a certain radius of manufacturers. Shipping panels half way across the country is not fiscally sane.
Rural USa for SIPs, absolutely. SIPs are dimensionally stable building elements. I have built many structures with SIPs and convinced that SIPs with ICF foundations is the majic combo. I have had these designs survive earthquakes and hurricanes. I want to build in tornado alley but the odds and wait time for a tornado to hit it are too great for me to take the time.
I even donated a SIP house to a school teach who lost her home in Katrina. I was told that Pres. Bush saw it twice.
Yea, I know SIPs. I know them extremely well, in fact. What I know is that if an presummed informed person did not build with them - then they are uninformed or have been misinformed either via ignorance or for a special agenda. Shipping to a 500 miles radius is typically $750, but that can vary somewhat. Hell, building a stick house a contractor will blow considerably more than that amount standing at the lumber supply counter while his crew stands around awaiting material. At the very least a contractor will spend more for cleaning the mud out of a stick house than for SIP shipping, meanwhile the ordinary stick house will take up to 3 years to dry out... plenty of time for mold to grow inside cavities.
As for strength, my SIP systems are >3x stronger than 2x6 -12"o.c. constructiion. The manner of SIPs lend to balloon framing very nicely. I do other things to SIPs making them near zero energy for ultra-high thermal efficiency. Granted, one must be flexible to get past the learning curve of SIPs but the rewards are very much worth the effort and investment. For instance, the manner to which I engineer my SIP house affords me to be weather tight under a shingled roof in one day, from atop footer upward. In some cases the siding has been installed and the shell interior sheetrocked.
People overthink SIP cost. What people are omiting from the equasion aside from speed is ownership affordibility. For instance, smaller HVAC cost less initially and more affordable to replace in 20 or so years. Feel free to read some of my other posts to gain more insight about SIPs. Suffice to say, properly staged SIP homes are truely amazing. Want a fireplace without the mess? Install the smallest potbelly wood stove and one can live in an enormous sauna if so desired.
As for Rural USa, there is a supreme advantage for any builder to have everything at the site necessary to complete a shell ready for fast install. I just cannot speak any more highly in favor of SIPs.
We did an SIP house back in the 90's. All we did was the frame work. I don't remember it well but the manufacturers rep was running the job. Everything we did went up okay but there was no time or labor saved from what I remember. It kinda fell apart after that as the subs didn't know how to make the electrical and plumbing work right. The structure ended up being torn apart and the SIPs sat on the property for years going to rot. They never did finish the house. If energy savings is the goal, it doesn't compare with AAC as a finished veneer. A 2" thick piece of AAC in your hand with a torch blowing on the other side of it, you won't feel it even get warm. We've built a few residences with 4" AAC as the finish veneer with an elastomeric paint that looks rich and you can just about heat the house with a candle. No 2x6 wall construction necessary. I'm not even sure any wall insulation is really needed but it's a requirement here. We have several apartment projects downtown that are AAC as the interior and exterior finish. A/C loads were figured at 1 ton per 1200 sq ft to give you an idea. Normal is 1 ton per 600 for our heat. We get most of our AAC from Mexico and it's a very good product. SIPs, I wouldn't have a clue where to buy it and really wouldn't fool with it as there are a lot better products out there now.
We are currently in the process of building a new home using SIPs. We even went to a Superior Wall precast, insulated panel foundation system. Our designer, who happens to be our son is very well informed in the benefits of using these methods. I trust him fully that he would not recommend something that would not be cost effective or safe for us. (I have been doing a lot of research to verify things, not just following blindly.) Our complete structure with 4 1/2" wall panels and 6 1/2" roof panels will exceed the newest energy efficiency codes by a substantial amount. We have no issues with plumbing or electrical, as all these things were well thought out during the design stage.
Location: Central Atlantic Region, though consults worldwide
266 posts, read 449,910 times
Reputation: 95
Quote:
Originally Posted by TrapperL
We did an SIP house back in the 90's. All we did was the frame work. I don't remember it well but the manufacturers rep was running the job. Everything we did went up okay but there was no time or labor saved from what I remember. It kinda fell apart after that as the subs didn't know how to make the electrical and plumbing work right. The structure ended up being torn apart and the SIPs sat on the property for years going to rot. They never did finish the house. If energy savings is the goal, it doesn't compare with AAC as a finished veneer. A 2" thick piece of AAC in your hand with a torch blowing on the other side of it, you won't feel it even get warm. We've built a few residences with 4" AAC as the finish veneer with an elastomeric paint that looks rich and you can just about heat the house with a candle. No 2x6 wall construction necessary. I'm not even sure any wall insulation is really needed but it's a requirement here. We have several apartment projects downtown that are AAC as the interior and exterior finish. A/C loads were figured at 1 ton per 1200 sq ft to give you an idea. Normal is 1 ton per 600 for our heat. We get most of our AAC from Mexico and it's a very good product. SIPs, I wouldn't have a clue where to buy it and really wouldn't fool with it as there are a lot better products out there now.
I have used autoclave concrete as interior partitions. It is good stuff with many fine properties. However, thermal resistance varies from 0.8 to 1.25 per inch thickness. Not that I advocate fiberglass batting that material is ~3.5 per inch thickness. Pore size and matrix material are extremely important if using the stuff for insulation.
Your 1200 sf/ton is a nice start however I have a Wash DC project that operates at 3650 sf per cooling ton.
I am also familiar with Superior wall systems. The manufacturing plant is located about 30 miles north of me. Only ever did one and that was the last one I'll do. All factory installed but my client had some issues. And I really don't like floating the slab in the manner the system does. It just not my preference. I rather like monolithic interlocked methods best.
I commend you for doing the homework, we need more like you. The problem I have with Superior Foundation walls is the gravel ballast as the footer. Soil conditions change, as does site drainage. What happens if the sump pump fails? See? I have absolutely no issue with the positive loading characteristics of the system.
I was sufficiently moved with the "Superior Wall" system that I developed my own patented system for one day placement. I can DM you if you would like to see it.
I have been doing energy engineering for almost 35 years. Spanning my career I have seen many energy code changes - I doubt very much we have not seen the last of them. If anyone can count on anything - its energy costs will continue to rise. Don;t forget that a code is a minimum standard.
I cut my teeth with Fortune 100 companies as Johnson Controls and Honeywell doing very large scale facilities. I decided it was time to bring that level of tech to the residential markets. I completely agree with SIP efficiency. The basic SIP is great but can be made even better thermal performers.. Great job though! Keep up the good work.
FYI: The mode of heat transport in thermal shells include convection, conduction, and radiation. SIPs are fantastic to resolve the first two however EPS sandwiched cores are virtually transparent to the radio-wave like energy of Infrared radiation. IR transpaency is an issue however it the re-radiation and related emissive properties of construction materials even most "experts" do not fully understand. Still, in all, SIPs are my favorite. To understand more about IR, both with reflection but also Low-E opaque building systems feel free to look at Soleil Insulation. Also bear in mind that any temperature above absolute zero contains IR direct and re-radiation potential. Soleil is soon to be a 501-c-3 corp to dissiminate information and further research for advancing thermal shell technologies. Pretty cool stuff.
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