Here are a few questions I've received via email and my answers to them.  I felt it appropriate to share.

1 - I've spent years researching all the different building methods, systems, and materials.  I decided the best way to go was either panelized SIP or a modular with spray foam insulation.  Some of the modular people do that now.

** I believe I've looked at all the possibilitie: structural insulated panel (SIP), insulated concrete forms (ICF), typical modular, and modular with spray foam.  I wanted ICF or SIP, but found local site-built costs prohibitive.  Spray foam in a modular is great (that is actually what I started looking for), however SIP walls are even better because they eliminate nearly all thermal bridging found in a stud wall with spray foam.  Penn Lyon actually suggested using SIPs when they declined to use spray foam as I requested (they have had issues with nail pops in the past).  For those of you who go forward with your own SIP/modular project, I believe you'll find the cost reasonable - especially when compared to the same house site-built.

I've found the SIP/modular combination is the most cost effective way to go - bar none.  The other cool thing is that Penn Lyon can put anything you want in your house - high end or modest - and it comes in nearly finished.

2 - My biggest problem is trying to figure out if what we want to do is even financially feasible.  Land is going to eat up a good portion of our budget.  I am very curious how much you estimate your home will cost per square foot, excluding the cost of land.

** Honestly, I don't think we are going to know the exact number until we are done.  I can tell you that the four modules are $192,000, but the excavation and finish work still needs to be done (this can add significant cost to the project).  If I were to guess, I'd say that we are ~$110/sf.  Keep in mind, I am acting as my own GC for some things, and this is a pretty large house.  A soup-to-nuts package from a general contractor will be more (per square foot), but the overall cost would be lower for a smaller house.  I spoke to at least a dozen contractors - not one could site-build this house, with studs or SIPs, for the SIP/modular price.

3 - From what I've read standard SIP constructed homes have very little waste and get assembled very quickly on-site.  Why did you decide to do modular SIP?  Was it more costly than doing a panelized SIP?

** I first got a quote from a reputable company that assembles SIP houses.  Their cost to me for the structural shell (only) was $182,000 for R23 EPS SIPs. I estimate that going site-built would cost us approximately twice the modular cost.  What is really neat is the fact that all the construction efficiency of SIPs also help to make modular building more efficient as well.  When you add in the other benefits of modular: built inside in a controlled environment, reduced waste, built stronger to travel down the road, and a complete house built in three days start-to-finish, it is a total win-win.

4 - Did you hire an architect for a custom design or did you use plans that the SIP or modular people already had?

** I interviewed some architects, but decided that I could put the $25,000 fee to better use.  My wife and I designed the home from the ground up.  Well, she did the inside layout and I did all the engineering / energy efficiency stuff.  All the structural drawings and the like are done by the modular factory.  I expect that the cost would likely be a bit lower if we chose a plan from their standard list, but it can't be that different.  The cost to build modular SIP versus 2x6 and fiberglass (R23 EPS SIPS) is a NO-BRAINER.  It would cost more to put a layer of foam board over the outside of a stick-built house.  As long as you keep in mind how these houses are constructed - they are basically large boxes; however they can build some amazing stuff.  If you can afford the architect, go for it.  If you can't, and you are not able to create your own design, there are literally hundreds of "standard" modular designs to choose from.  Pick one of those and build it with SIPs.

4 - Did you have your land first and pick a house design that best fit the land or did you have your house design first and then tweak it to best fit the land you ended up with?

** Our project has sort of "evolved" over the past three years.  We knew we wanted to build a colonial even before we had land.  The main thing we could not determine until we had land was if we could do a garage under.  If you want to take advantage of solar energy, whether PV, hot water, or passive, you will want to keep direction in mind.  Finally, we had the opportunity to choose one of two different lots.  We chose the lot that allowed us to face the front of the house south.

We did learn one expensive lesson - make sure the land you purchase is buildable before you buy it!  You would be amazed at how long your project can be tied up, and how much it costs to satisfy the demands (Conservation, Building Department, etc.). 

5 - Correct me if I'm wrong, but if looks like you are not using SIPs on your roof.  How come?

** Correct!  The modular factory builds their folding roof systems so efficiently that the cost is quite low.  We could have gone with a SIP roof, but that would have needed to be constructed 100% onsite and involved a crew and a crane.  This also means your house is exposed to the weather until the roof is done.  It is far less costly to have the factory build a traditional roof system and then insulate it with spray foam.

6 - What were the factors that made you choose Oasis for your foundation over Superior Walls and others you may have looked at?

** Part of it was simply customer service.  I spoke with both Oasis and Superior.  Oasis is just great to work with.  I found the guys at Superior acted "superior" for no good reason.  The Oasis walls also come in "finished".  You instantly have a usable basement.  With Superior, you still have to finish.  The one thing I would like to see with Oasis is the possibility for "up insulating".  It just did not make economic sense to do it.  You can add extra insulation to the Superior walls, but you still have to finish.  Oasis walls are also more competitive with traditional poured walls.