Good afternoon to everyone,

I am new to the forum and am seeking to tap your collective wisdom.

We are getting ready to build a very small garage with a living space above it.  Only the living area will be constructed of SIPs.  The structure is 28' wide by 26' deep.  The walls are 8' high with gabled ends that are 14' high (all wall measurements from subfloor of living area).  The roof is pitched at 9 in 12.  There are two "dormers" on the house. One is centered in the front of the house, 10' wide and roughly 12' high.  The other dormer is on the back of the house, 4' wide and roughly 10' high.
The plan calls for 6" exterior walls.  The measurements for this structure would require 1300 sq. ft. of panels for the walls, and 1450 sq. ft. of panels for the roof. There is nothing too elaborate about this structure. In fact, the plans were purchased from a company that sells to "do it yourself" types.

I submitted the plans to a manufacturer's representative for the southeastern US.  They quickly gave me a budgetary estimate for the SIP package of approximately $20,000. The price seemed reasonable and may be spot on.  But, I have started to question that based on reading I have done in this forum.  One particular member, BenMiller, described a much larger house in this post, http://www.greenbuildingtalk.com/Forums/tabid/53/forumid/5/postid/27810/view/topic/Default.aspx.  His package price was roughly $11000.

I know that it is tough - if not impossible - to guess at the package price for a project. But, for a living space of roughly 720 sq. ft. of living space, I am starting to question that price.  Considering 2750 sq. ft. of panels, that is $7.27 per sq. ft. of panel.

Does that seem right?  I know the price is subject to change as the final design comes together.  But I don't expect the price to be less.

Any thoughts? Thanks in advance for your response.

The price includes roof beams, purlins, screws, house wrap, foam for sealing joints, etc.  Basically everything but shipping.  The windows and doors are factory cut.

Some additional reading suggests that the calculated price/sq. ft. is pretty close to other package prices when you consider the costs other than that of the panels.

It seems like a lot of money when considering the overall budget for the project.  The thing that is lost in the calculation is the time and labor costs that would be incurred in building the structure by traditional means.  Perhaps I was overtaken by a moment of panick when I read about package prices for other projects. 

I really appreciate your help.

JNR

Leonard;

ICFs will always cost more than SIPs, you missed the ICF bracing, concrete pump, steel rebar and labor to place both. Difficulty in fastening anything substantial. And if you have an oops! expensive to fix.

We recently placed a steel SIPs roof on an owner-builder installed ICF house. -What a freaking nightmare! It took us 3 days just to prep the walls/plates to get good enough to attach roof. ICFs were full of honeycombs and a couple of wall that were  bulging & 4" out of plumb on a 2 story.

 

mmacgowa,

suggesting and telling are two different things, your statements are often unfounded or incomplete. The bottom line is you get what you pay for. There are some fine energy efficient modulars and mobile homes too, if price is the only consideration.
It is why some of us drive Hyundai's and some prefer Lincoln's

intransit;

Giving a warranty on a manufactured product should give some level of confidence.
Plywood is a manufactured laminated product too and  I have  seen plywood delaminate ,what do you think your recourse would be 10 years down the road if it fell apart or if your roof trusses failed 
If warranty is a major concern you should be glad your supplier is offering one.
Most panel testing is done with a safety factor of only 85% lamination and load testing with 2.5x  safety factor.

SIPs are not new and have been in use for over 50 years, I haven't heard any delam issues.

leonard;

The concrete contractor has over 100 employees, he does not lack for labor availability. He did make a well thought out intelligent decision as to what system to use. His house is 4 stories high!

A full thick concrete wall is pretty stong, but ICFs are just 4-1/2" sandwiched between 2 layers of 2-1/2" foam. From our experience, we found the ICF gables to be quite shaky when setting ridge beams.
Stamped engineered plans are stricly a regional requirement and not always needed. In Florida every structure (including ICFs, conventional & garden sheds) are required to be signed & sealed.
You say HUD's ICF prescriptive guide allows most? Its that to say ICFs are limited as well?

I never had any argument that ICFs are becoming competitive, It just takes too darn long to build one. Did you calculate additional construction loan interest in your analysis?

You are also sacrificing about 125 sq.ft. of useable living area on a 2500 sq.ft house just due to the additional wall thickness!

@ $85./ sq.ft. you just lost $10,625. now thats a bargain!