Cost difference b/t 1.5-story 20X32 and 2-story 20X34, both with full basement?

[Charcoals]

I purchased the plans for the 2-story Universal Cottage a year or so ago and still like the design very much.  However, I'm wondering if there would be much of a cost savings in building the 1.5-story of similar size (20X32 for the latter versus 20X34 for the Universal Cottage), especially since I would do a full basement either way.  My sense is that the cost savings would not be that great, since a full basement would be the same cost either way.  The main cost differences, then -- so far as I can see -- would be due to some extra siding, insulation, framing and windows.  Without "running the numbers," my sense is that the cost difference of these two scenarios would be about 10 percent.  Anyone care to comment or tell me I'm way off base (and why)?  :-)

By the way, I won't post pictures of it because doing so would violate copyright laws, but anyone wanting to check out a very cool two-story cottage (and a rather "thin" one at that -- I'm guessing maybe only 16 feet wide) should see pages 176 and following of "The Getaway Home" by Dale Mulfinger (2004).  The book has about ten pages, and lots of photos, devoted to the phome, which was built somewhere in Michigan, amongst pine trees and next to a pond or lake.  The home appears to have a full basement, too.  In fact, it also uses the third floor for living space rather than leaving it to attic space.  I really like how the second-floor master bedroom features a sleeping porch directly above the main floor porch.  I also like how there is no front entry to the home.  I think doing away with a front entry allows one to make better use of the living room in such a "thin" home.

Thanks in advance.

Charcoals in Minnesota (long-time lurker but can't wait to get started building!)

[Squirl]

I don't think you are that far off on your estimate.  With a two story you buy shorter (8') rather than longer (10 or 12') studs. The cost is roughly the same per foot, sometimes the 8's are cheaper because there is more standardization, and more common.  Much of the space in a 1.5 story is a high pitched roof.  This requires more insulation, roofing, and sheathing.  It works out close to what it costs for the extra siding for the complete studs.  Recently, I worked through a complete spreadsheet for a 1.5 story (12:12 roof) vs. a 2 story with a shed roof (3:12), and the 2 story came out to be the same price.  I think I am going to go with the complete second floor myself, simply because of the ease in roofing.

[Charcoals]

Thanks for the reply.  It's good to hear from someone who has "run the numbers."  I don't know that I would save any on insulation in a two-story, however, as I plan to use icynene sprayed right under the rafters (rather than on top of the second-story ceiling).  I also plan to go with a metal roof, and I've heard that's a good combo when using icynene.

Thanks again.

[Squirl]

Sprayfoam is really expensive per square foot.  You will probably save money with a lower slopped two story.

[duncanshannon]

Recently, I worked through a complete spreadsheet for a 1.5 story (12:12 roof) vs. a 2 story with a shed roof (3:12), and the 2 story came out to be the same price. 

Can you share the spreadsheet? Sounds interesting.