you might contact one of the purveyors of prefab houses. they're usually advertised in dwell mag. even if it's just to get the word out and not for a real project, they should be willing to help you, i'd think.

problem is that these different prefab experiments, while promising, are still in the early stages and therefore don't have a 'market' price yet. they haven't reached a point of economy through quantity and are therefore still running higher than targeted costs.

they may never be as low as conventional construction anyway. one of the goals, as much as affordability, is to get architect-designed and [gasp!] possibly modern houses down to a similar cost to what is commonly considered affordable - so there's an option.

Try contacting these guys.

cuttingedgehomes

I was consulting these guys on a prefab townhome style project that I was working on last year.

there are so many parameters you're not defining that it's impossible to really give you any good advice, beyond contacting specific manufacturers.

a couple observations: 81/sf is completely unrealistic as a construction number for any major metropolitan area. even the so-called 'cheaper' places. i don't care what means says.

second - if you're thinking pre-fab, quantity means something. if you're asking a shop to re-tool their assembly line for only one house, expect to pay a larger premium.

third - style counts. if you're trying to do more modernist prefab (or conventional construction), be prepared to pay a premium with most contractors. may be anywhere from 5-20%. reason being, to build 'modern', especially minimal, requires a higher level of attention to the details and that costs more.

in general, right now, it's cheaper to site-build than to prefab. unless, of course, you have volume on your side.

Read the recent interview with Michelle Kaufmann in Dwell. She built her first Glidehouse with typical construction and built a prefab version for a client at about the same time.

I believe the price for the Glidehouse is around $125 per sq. ft., which is pretty reasonable.

As laru noted, $81.25 is just not realistic.



Design matters a lot. You need to design within certain parameters for prefab to work well (truck length, # of pieces to assemble, etc.). To do a 'real' comparison, you need to have it pretty well thought out. Comparing a number from a book to another random number will not be accurate at all.

Thank you Steven, b4g, laru and trace for your insight.

To clarify my project further, my purpose is to examine the pure construction cost difference between conventional and prefab construction through a line item spreadsheet. I did not intend to specify the location as a factor. For example, to demonstrate location cost difference, location factors can be multiplied to "basic average costs".

However, it seems that many of you imply a more specific approach for the project, such as how Michelle Kaufman demonstrated in her experiment. If for example, I were presenting a report to you all as potential investors, would you be more persuaded if I compared a more specific project or that I compared an average cost comparison? What are the pros and cons?

I have never entered a discussion forum before but this forum has been helpful so far. I appreciate your taking this request for help seriously.

What is the average sf construction cost, not including land, of a 2000 sf house in California for example? Where would I be able to reference a reliable number?

One big "line item" which your book might not be addressing is the cost of labor. There is going to be a huge difference in the labor of an "average" cookie cutter home, an "average" architect-designed home, and an "average" pre-fab home. The pre-fab homes, by their very nature, are designed to require less labor and so even if your regular home costs a lot less in material psf, the pre-fab home will make up a lot of this ground in labor costs. Another thing that will drive up the cost of a home is the question of *type* of labor....is it union, or non-union? Union labor is going to cost more.

Regarding basic material costs, however, as the others have said, if you contact the manufacturers directly, they should have this type of information on hand.

Incidentally, some of the pre-fab homes have specific floor plans that they offer so you might want to start with those and then go back to the "regular" homes....

Thanks OldFogey. Would a homebuilder be willing to do a line item breakdown for me even though I am not not buying a house? It seems that in the companies they are rather unwilling to share their sf costs in order to stay competitive. Do you have any suggestions for people or companies?

I front end pre-fab and modular homes. Everyone has been correct in their statements, as it applies to the modern style homes. I have done "traditional" styled prefab, even custom pre-fabs that were as low as $70/sf, without any upgrades (they still sell these like cars). That being said the suggestion of taking a pre-fab floor plan and then taking it to a conventional contractor to give you an estimate would probably get you farther than trying to put together a spreadsheet. I doubt their are any modular/pre-fab manufacturers that will provide you with a line item price for anything other than the extras. They don't want people to know how cheap it can be, because if we charge the same as conventional construction (the unpublished goal of us front-enders) then we make more profit and provide a "superior constructed house".
Email me and I can set you up with some starting plans with their base price and a listing of upgrades and "not included" construction that will be the same from modular to standard construction (no one can ship a foundation yet). Of course these prices only apply to the Calilfornia market.

j

Thanks!