I'm building a small 950sf house this spring / summer (950 first floor living space, 950 basement, +garage, +2 porches). I have been following the SIP's and ICF building methods and know their performance advantages, but on a house this small, can their additional cost be justified?? Two of the key things that I've learned about home performance are 1, air infiltration is your biggest enemy and 2, anything more that 3" of polyurethane insulation is just overkill. (For my mid-south region) I can achieve both of these with semi-standard construction.

So the options I would like to discuss are:

1. ICF basement, with SIP's walls above.

2. ICF both basement and first floor walls

3. Standard concrete basement with 2" rigid on exterior. EEBA advanced wood framing on first floor.

Initial cost vs lifetime cost. I intend to live in this house for the next 40 years.(Knock on wood : )

Thanks

You might want to run heat loss calculations on all 3 and see what the real world difference is likely to be.

Also what are the capabilities of your local contractors? If all other things are equal go with the system that the contractors know, more likely to get it right at the right price.

There are other advantages and disadvantages to every building system that may or may not be important to you. ICF makes a very strong, quiet house. Bugs won't eat it (but they may tunnel through the foam) and it's fire resistant, or at least the concrete is. I think ICF is probably the best, but it is expensive, and hard to modify years down the road. Steel SIP's are also a good choice. Again, rot, fire, and bug resistant. Not quite as much of a bank vault, but easier to work with if changes are desired after the fact. The two biggest advantages to regular stick construction are price and being able to find someone that can build your house.

It's really hard to tell what system is best strictly from the stand-point of economics. A moderate climate makes it even harder to calculate. It's pretty much a given that fuel costs are going to continue to rise- possibly dramatically. So calculating savings at today's fuel prices is probably not accurate, but how do you go about guessing how much they will go up? A less efficient house will also require a bigger heat/A/C unit to begin with, which will cost more. Different construction systems may also have different insurance rates, and different re-sale values over the years.

People will say that you can build a stick frame to the same energy efficiency as the other methods. I believe this is true, but only if the builder knows what they're doing. The cost to produce a really energy efficient stick frame starts running up the costs to the point that there may not be much advantage. Every layer of sealing and insulation is more materials, and especially, more labor.

I'm still pondering all of these variables myself. Ultimately, it will come down to what I can afford. I'd love to have an ICF home with a SIP roof structure, but that might put me out of the market altogether, in which case, it isn't very practical.

As the cost difference between standard concrete plus insulation and ICF is so small it does not make sense to pour a standard basement. As to the main floor there are so many variables that need to be taken into account. If the plan is to live in it for 40 years, I would go ICF all the way. Wrap it with something like James Hardy siding and put on a steel roof of some sort and you are almost maintenance free! After the first 10 years will all the joints in the advanced framing or the sips still be air tight? The ICF will probably be! Do you live in an area with extreme weather? Hard to beat ICF in hurricane ally.