timber joist span chart for mezzanine

[sjvicker]

I'm starting to plan the mezzanine for my shop build and I really like some of the old construction in the PNW with big timber joists, beams and posts. My goal is to span 20' and have a 4' overhang giving me a total length of 24' and an overhang less than 25%. I can find a span chart that says I'd be good with 2x12's on 12" centers but in that size 24' lumber is hard to find or non-existent.

I'd like to mill my own joists and am looking to verify what spacing I would need if I did 3x12x24' joists. Does anyone know of any charts out there for doug fir that might give me the span tables I need?

 

[The Tool Tyrant]

Saw sized lumber may look cool, but now days with manufactured joist availability, I wouldn't give saw sized lumber any thought. The 2 big problems with saw sized lumber is # 1, inconsistent dimensions...a 2x12 could range from 11-1/8" to 11-1/2" wide. #2, crown...one may be totally straight while the next has 3/4" of crown. It will be a cold day in hell before I'd use saw sized lumber in a floor system now days.
Just my 2 cents.

 

[sjvicker]

I would hope that if I mill my own I could minimize the dimensional issues.

Eventually the room below the mezzanine will be my wood shop and the space above will be a hang out / lounge area. If it was going to be living space I'd agree with you but for the use I think this will be fine.

 

[Stuart in MN]

Try looking for beam span instead of joist span - I looked around and it appears you can get information on longer lengths with larger size timbers that way. There are some calculator pages out there where you plug in the span, load, deflection, etc. and it pops out the required size beam.

 

[billconner]

What will you use for decking? What did you want for a live load? I say 30 or 40 at most for a lounge area, unless your having dance parties for 50 or more.

Since a no. 2 2x12 for 30 psf will span 23' 12" o.c., you'd be fine with a double 2x12 at 24" o.c. Around here, a rough sawn (nor sure if that is aka saw size) I could use a 3x12, though I might go to 18-20" on center, probably using rough sawn 1x8 or 10 or 12 for the deck.

 

[Hank11]

Green timbers will take a long time to dry and will likely crack, shift and twist a bit too. Buying nice dry ones will cost you.

I suggest an engineered beam and then box it with some rough sawn 1x.

 

[billconner]

Not where I can take a pic but my whole 28 x 32 garage - small barn really - was built of greenish rough dawn white pine. No regrets. I'd do it again. Lots of house around here also all built of roughsawn (and with hand tools).

Found a pic.

 

[Hank11]

A lot of this has to do with what material is available where the OP lives. But you can buy engineered beams most everywhere and know exactly what it will do.

On the other hand, if you have a mill nearby that will saw what you want and deliver it green it might work out OK if you choose a specie that air dries well and is stable. You can use the charts for finish lumber by looking at the dimensions that would result in the finished material in the chart. All that assumes you can judge the grade of the wood on your own.

That shop shown above by billconnor looks mighty nice.

Your rough 3x12s could be essentially the same as 2 finished 2x12s. But thats all a guess unless you know about wood enough to make an informed decision. If not, stay with engineered stuff.

 

[billconner]

Probably not the same everywhere, but rough sawn here is $0.60 a board foot. Just looking at HD 2x12s, it's $1.45. You can overbuild and still do it for a lot less. (And it smells nice. )

 

[sjvicker]

I need to span 20’ with a a 4’ overhang so a standard 2x12 on 12” centers would work.

I have a mill and have some 100’ Doug Firs that will need to come out for my house build. This is the perk of being on a PNW timber property but unfortunately I have no worthwhile hardwoods for other projects.

I’m looking to do rough sawn 3x12s on 16” centers and I’m not too sure of the decking yet. I do know I don’t want to be looking up at OSB so that limits me a bit

 

[sjvicker]

Not where I can take a pic but my whole 28 x 32 garage - small barn really - was built of greenish rough dawn white pine. No regrets. I'd do it again. Lots of house around here also all built of roughsawn (and with hand tools).

Found a pic.

That is amazing and exactly the look I’m going for

 

[billconner]

That is amazing and exactly the look I’m going for

Thank you. I have not dealt with storage, just had to get everything out of old garage do I can insulate and hopefully finish conversion to living space before cold.

I frankly really enjoyed working with the rough cut. I didn't find the variances in dimensions to mean much. I didn't mention that besides the low relative low cost, boards average a foot longer than what I pay for, i.e. I ask and pay for 12' and many are over 13'.