Hi All,

So my wife and I are currently paying a mortgage on a 1919 bungalow in Maine (We saw -30F this last winter). As you can imagine it is not the most energy efficient, or low maintenance house in the world. We are considering building our next house and SIPs look [almost] like a no-brainer. Here is our general goal and some questions that go along with said goal.

We would like to start by living in an “in-law” apartment above a garage. Hopefully we could construct this for less money than a full sized house. Do SIPs make sense in this application? If so here are my questions from the bottom up:

The Slab
1) Is there anything in particular I should watch out for when planning a SIPs house built on a slab? I know it must be incredibly level. Is there anything else?
2) What are some of the best practices when designing an energy efficient house on a slab, and can SIPs be useful for insulating the slab?
3) Radiant heat the slab or is that a waste of money?


The Garage Level
1) Would it make sense to use SIPs on the first floor? I would like to keep the garage level “warm” which means probably in the mid 40s... maybe a work shop in the back could have a pellet stove or some sort of space heater.
2) Anything special I should look out for having SIPs be used as exterior walls on a bottom garage?

2nd Floor
1) Are there any downsides to using top-flange joist hangers? Fire safety issues? It seems like it would be the cleanest, most energy efficient way to add a 2nd story.
2) When using SIPs for floors is there anything I should look out for or ask the contractor?

Roof
1) To vent or not? I would like to use either a standing-seam metal roof or maybe one of those metal roofs that look like shingles (interlock or equivalent).

General Questions
My two biggest concerns are pests and incorrect installation.
1) Here in Maine we have red squirrels, mice, and chipmunks that can do a number to houses. What are some methods I can look for to protect my investment? Metal panels don't seem to be structural so the cost would most likely be a lot higher?
2) Inside air infiltration through seams would be a big problem here in Maine, especially if using OSB. I would hate to have panels rot from condensation. Is there anything I can do other than pick a competent builder to ensure joint seals are done correctly?
3) There seems to be a million companies that produce panels. What should I look for and what should I stay away from? PU vs EPS seems like a pretty heated debate, but do either one of those have any serious downsides that I should really look out for? Maine has some pretty extreme temperature and humidity ranges.. -30 in the winter to almost 100 in the summer with high humidity. I am not sure if this helps determine the “best” panel for my needs.
4) In your opinion what are some good, low maintenance siding options for a SIP construction? I really like cedar clapboard but would that cause a problem with moisture or fastening? Vinyl is probably safest bet?
5) When routing plumbing from the downstairs up through a SIPs panel into an interior wall do you just a drill a hole through the panel, run the pipe/pex and then seal with a foam? I am sure this is something the contractor would know.

Phew! Sorry to bombard you all with so many questions. I have never heard of SIPs until recently and I am pretty excited by them.

Thank your for your time and input!
Sam

Before you get too involved, get on You Tube and do a week's reading/watching about SIPS and related vids. Most of your questions will be answered, but there are conflicting ideas, so THINK your project through before one shovel-full of dirt is moved. I built a SIP home and I love it, but technological advances MUST be considered. Look at ICF, metal SIPS, and newer (for me) cement fiber SIPS. I have in-floor radiant heat, but when I build another home I will use ICF walls at least out of the ground and put 6" of rigid foam under the slab making an insulation swimming pool in which to pour a slab, and I'll use metal SIPS for the roof. Insulation and air sealing are very important. Then you get into windows and doors (and their placement), roof over hangs, site orientation, vegetation (trees), PV cells, air conditioning, air exchangers, blower door tests. It is a long list, and there are many pros here on this site that are willing to help you. Good luck Dan

What is a good source outside of You Tube?

swinchen, your climate is much different from my own, so there are some elements to your project about which I am not informed (a vented roof for example is ridiculous in the gulf south but in Maine it applies to ice dam prevention, so this is something you need to do some research on over at buildingscience.com).

About metal SIPs, not sure what you meant when you wrote that metal panels were not structural. But if you mean metal SIPs, then yes of course they are indeed structural and they seal better, and have better spans than OSB, and they don't rot. However I am not sure if you could find a metal SIP supplier near enough to you.

For siding, what is typically used successfully in your area? There is no reason why that couldn't be used with SIPs. But again you have to consider the climate in regards to the way it is applied.

About your garage-first approach, you need to check with the local building inspection authority or planning commission, because some areas do not allow building a secondary structure first. Now if it meets the requirements of a primary structure (in regards to square feet and setback, et cetera) then you might be able to start out for example by building a garage with living space above as a primary structure. Then later on that can be the detached garage to a bigger house. But in my area, a two car garage with say 500 sq feet of living space above, would not meet the zoning requirement of a primary residence, so the house would have to be built first (or at the same time).

About the slab, you might be referring to an FPSF (frost protected shallow foundation) where a slab-on-grade foundation is isolated from the surrounding soil with foam insulation. Otherwise in Maine I would think the frost line would be pretty deep in minus 30 so the footings would have to go down as deep as a basement, so why not just build the basement. But I would think radiant heat in the concrete would be very smart, and is commonly used in conjunction with an FPSF in cold climates in Europe.

Is state of Kentucky a place where SIPs makes more sense than ICF due to climate?

James, what makes senses ultimately depends on what criteria YOU deem to be important in making this decision.

Typically, one’s primary criteria is meeting some given R-value building assembly requirement/goal within some given budget. Then you see what is actually available/achievable at your location and what it will cost.  In some locations the products or experienced contractors may not be available at all or may not be available at a cost that you are willing to pay.  So you may want to throw 2x stick construction on your decision/feasibility list too.

Once you acquire this primary criteria data, then you might also want to consider secondary criteria like are you in a wildfire area where high temp puts the structural integrity of a SIP building assembly at risk, etc.  Bottom line, you need to first sort out what criteria is important to you and accomplish the research for your location.  Once you do that then you can post what you determined and the ICF/SIP proponents will provide you more information and guidance likely making your decision even more difficult.