wider 1 1/2 story?

[jamest]

Hi,  and greetings from Afghanistan!  I'm currently serving in the US Army, (CH-47D Pilot). and doing much research on small cabins.  I see that folks have modified the 20X30 1 1/2 story cabin by making it a little longer...but has anyone make it wider?  Say 24X30,  or even 30X40?  Thanks,  James T  

[John Raabe]

The limit of simple span joists is about 20' so it is easier to lengthen than widen the 20' plans. For 24' or more in width you will need to have an internal beam and post support for both floors so this complicates the design a bit - but it is a rather trivial modification for a good builder, designer or engineer.

[phalynx]

Wouldn't I-joists and trusses work to go beyond 24'?

[rwanders]

More width is definitely worth the effort/expense. At least 24' wide provides many dividends in the floor planning stage.

[John Raabe]

You can definitely get open web trusses that will span 24' and beyond. I-joists can do it too, but get expensive. You can go up to 32' with a 16" deep super beefy unit spaced every 12".

So, the 20' limit is more an economical decision rather than a purely structural one. Most builders go to a girder and post system around that point.

[jamest]

Hi everyone!  well,  thanks for the help.  I've been researching the 'open truss' floor joists.  They look like they'd do the trick.  The biggest reason for a wider span would be to have more floor plan options.  Thanks!    Hope to be building sometime this coming year!  James