cabin width

[tarlac]

a question for john,
have purchased plans for a 1.5 story house.  At this point we are considering making the cabin wider, possibly 24 ft. to 26 ft., also adding an additional length to the footprint.  Maybe out to 34 ft. long.  I really like the roof dormers and the open greatroom.  Can i modify my plans to do this without major changes.  Not a lot of
building experience.  This building would go on a concrete foundation. crawl space or full basement has not been determined at this time.nseats

[suburbancowboy]

The additional width will cause you to  probably have to go to manufactured trusses.  Length is no issue.  I think that a 20X40 might be cheaper.

[MountainDon]

Increasing width requires reassessment of several structural elements; floors and ceilings and their supports and the roof structure.

Floors and ceilings will need either center supports or to be engineered joists or trusses. The roof could still be rafter framed, but could also be done with manufactured trusses as well.

Making length changes does not require the re-engineering that going wider requires.

[Don_P]

Although it does require design modification, increasing the width allows ample room in the loft without kneewalls. The rafters in the loft area can tie directly to the floor joists, a simple prescriptive design. At 24' stairs get easier to work in. I prefer to build this size with a center girder under the main floor, you are then set up to run posts or walls up to support a ridgebeam over the greatroom.

[mgramann]

I am actually planning something similar, and asked some of the same questions.  Here is a link to that thread: http://countryplans.com/smf/index.php?topic=12520.0

As others have mentioned, there are really two options, ridge beams and girders or trusses.  After getting a very high big from a local company on roof trusses with a pitch lower than I wanted(to save on delivery) I thought ridge beams would be the only way.  Ultimately, I ended up sitting down with an engineer from Menards and talked it through while he sketched it up.  They have an excellent program where if you buy the materials from them, they do the engineering for free.  Menards was much more reasonable in price with their roof trusses, and I got the pitch I wanted as well, so I was sold in that department.  The floors were still up in the air for me.  I had originally laid out my floor plan with the intention of clear spanning, but once I realized 2x12s wouldn't accommodate this, I made changes to allow for a girder.  In talking with the menards engineer, he told me that with engineered trusses, the spacing can be a little wider(19.2?), requiring fewer trusses.  Factoring in this, not having hangers, and onsite labor savings, it made financial sense alone to use floor trusses.  Added benefits are that running utilities through the trusses is much easier, and I get to use my original floorplan!

For a 24x40 building with a 12/12 pitch, 4 9ft dormers, 60psi snow load, with 2 levels of floor trusses, the bill came to about $8800.  This may seem like alot, but I am contracting out the shell of my project, so once the labor/engineering savings are factored in, I am very happy with this number.

[tarlac]

your project seems very close to mine also. really appreciate your feedback. I am also planing on having the exterior and framing done by a contractor. My knowledge of building a structure from scratch is a little weak. Also i need to get it weather tight in a short amount of time ( western mn.)  $ 8800.00 for
framing materials sounds fair to me.  Also I would only need two dormers as we would like to have an open great room.  All the suggestions on this site are
most helpful.