Expert: Bruce E. Johnson - 5/27/2010

Question
Hello........

i have a problem i am trying to figure out, and wondered if you might be able to help.......

I am building a small barn for our horses and i am putting in storage for hay above.....it is only 20' wide making it 19'2" span.  i am looking at around 60-70 lbs per square foot of, i call it live load, the hay, and was figureing 10 psf dead load......  I can't seem to find any information regarding size of joist or spacing for this load........  Our old barn has 3, true 7*7's oak spaced evenly but they sag and are expensive to get them in the length i need.  

I was looking at 2x12 fir(or y. Pine) spaced either 16" or 19.2" apart, 3/4 sub floor with 7/16 topping it...........i really want to put up a sound floor(and cost effective), but don't want to be disapointed when i start putting up the hay........If i need to plan on a carrier beam under the joists i can, but need to know ahead of time.......

The fondation is 8" concrete walls for the first 2 feet, and average of 10" of concrete floor on soild compacted stone.  

if need be i was think about doubling up every other joist if need be.

I truely understand if you cant help me, but if you have a direction i can turn to look for any information i need it is greatly appreciated.

Brian Alt

Rural Ohio,45822



p.s.........no building codes here where
i live, except septic....

Answer
Hi Brian, if you really want a heavy duty floor system I suggest using engineered wood girders that can be purchased from truss manufacturers in your area.  A girdered floor truss system with 24" to 32" spacing with tongue and groove 3/4" plywood would probably cost comparably to a dimensional wood floor system and be actually engineered to support the heavy live loads you are talking about.   Another option would be LVLs or laminated joists, in your case a 20 foot span with LVLs would probably require a 1 3/4" x 18" and 24" spacing.  Again, LVLs can be purchased from truss plants and lumberyards.  As far as dimensional lumber goes: for heavy loads a 2x12 Southern yellow pine gives you almost 20' at 12" spacing...check out this span calculator at:   www.awc.org/calculators/span/calc/

I hope this information helps feel free to write again regarding this or other matters, sincerely bruce e johnson