ceiling beam span (newbie introduction)

[vester]

Hello, cool site you got here. I was beginning to wonder if there were people building cabins out there. Been searching for a group like this.

Anyways, I'm a shed builder. So doing this cabin thing is kinda new. But I've been dreamin about a charming, rustc cabin with board and batten walls and SYP flooring  for some time now and things are looking good for me to start my project this summer.  I'll be using this site and pickin the brains of some you cabin builders for ideas and help.

My project will be a 16'x48' 2 story barn with the gambrel roof serving as the 2nd floor. I'm going to put in a couple dormers and windows on the end to let lots of light in. The interior will be done out of rough cut, white pine board and batten siding except for the 2nd story ceiling which will be tongue and groove white pine. I plan to lay 2x6 southern yellow pine on rough cut beams for the 2nd story flooring and this will serve as my finished ceiling for the 1st floor. This will be a permanent residence for my wife and I. And if this project goes well I might consider building cabins along with my shed business.

I cant find a "wood beam" span table anywhere and I'm too dumb in math to figure out the stress loads. So I need to know what beam size will span 16' @ 24" o/c without being total over kill. I know a 2x12 will do it but I'm not sure if this is the look I want. I'd rather have the floor support wider and not as deep.

Also, has anybody laid 2x6 tongue and groove flooring over 36" o/c supports? I've been told it can be done but it might be a little springy. The second floor will consist of 2 sleeping rooms and a master bath.

Thanks
Vester

[JRR]

You will find some good info on joist selection in the "referral links" of this website.

If you also look at the "Gambrel Roof" project in the builder/owner's photo gallery, you will see a 16' wide building.   You can see that staircase landings are a little close to the walls ... even though a 'knee-wall" was planned in.  You may want to use an 18' ft width even if it means joists at 16" centers.  

If you use the balloon construction shown here and create the knee-wall, you can then install short windows instead of dormers ... just a thought.

[John Raabe]

36" o/c will be fine for good quality 2x6 T&G. As for beams, good fir 4x12s at 36" will span 15' (16' wide structure w/ 2x6 walls) easily with less than 1/480 deflection.

[vester]

Thanks for the info. After reviewing my plans, I do think that I will extend my width to 18'. Because of the extra 2 feet do you think I need to go with 24" o/c for my 4x12's?

Thanks
Vester

[John Raabe]

I can't be doing engineering on this forum (and should have kept my mouth shut in the first place), however I would try to keep the beams at 36" as going closer lowers the feeling of the ceiling and becomes a forest of beams rather than a beam and plank ceiling.

All your structural choices need to be checked locally with a professional who knows the local codes and load requirements.

For a sleeping loft you could use very good (SelStruc) fir 4x12s @ 36" as a first guess for the design.