Why 20' wide vs say 24' ?

[HappyOne]

The plans are all based on a 20' width with comment about it easy to add to the width but what if one wants to use 24' ? Are we talking major problems or changes to the whole thing? 

[Don_P]

The spans become longer, or different, for joists and rafters. This will change their sizes. Adding to the length of the building simply adds more of the same sized framing. Certainly not insurmountable if you plan properly, I usually prefer 24-28' wide myself.

[HappyOne]

So if I was to use 24' roof trusses and I joist 24' floor trusses would I encounter anything else major I'd have to change?
Other than the footings, block etc of course.

Attempting to control costs where possible but we are looking to do a downsize from 4200sf and even if I stretched a 20' to a 40' length with a full basement and a half loft I'd be probably a bit tight with "stuff" - even after telling the kids to take it all. lol
Just thinking a 24' makes more sense and gives me easy to address U stairway too.

[Don_P]

That's pretty much it, getting those spanning members engineered takes care of that issue. I prefer to run a girder and break the floor into 12' spans but have done it clearspan. Spend a few more bucks to design it stiff if you do span the full 24'.

[Rys]

I was also curious about this. I've had a heck of a time figuring the spacing for my stairs in the 20' width.