pole barn header question?

mopower440 · Nov 20, 2003

well, got the plans drawed up for the pole barn, its a 24 wide by 30 deep barn with a gable roof, trussuess are 2x4 and set on 4 foot centers, using 2x4 perlins and metal roof, the only question we have is about the header boards that support the trussuss, should i use 2x8 or 2x10 boards? I figured since there is one on each side of the pole and its a metal roof with only 8 trussess, that the 2x8's would be fine, but want to ask here from more experienced people just to make sure.
I thank all of you for all your help, i know ive asked a lot of questions, but im fairly new at this, so bear with me, once i get the header situation squared away, all i have to do is figure the metal siding and roofing question i asked earlier and ill be set.
thanks again! /forums/images/graemlins/smile.gif

NIXON · Nov 20, 2003

I'd go with 2x10's on each side of the poles . Not a significant amount of money , considering the entire cost . John

lwh · Nov 20, 2003

How far apart are the posts supporting the header boards?

JLoaf · Nov 21, 2003

I'm a structural engineer and I have my office in a POLE BARN.
No kidding.
Assuming that the posts are spaced at 10' and the at the 2x4 trusses span 24', and using 20 lb per sq ft live load (minimum req'd by building codes), I found the 2x8's to be approx 30% over stressed.
The 2x10's check out ok. When you compare 2x10's to 2x8's,
2x10's have about 60% more bending strength and are 108% stiffer.
If my assumptions were right, I'd use (2)2x10's. If you are in a really heavy snow area, you may want to go with 2x12's?
Hope this helped.

mopower440 · Nov 21, 2003

The bays are spaced at 9'5" apart and the trussess are 4 foot OC for a total of 8 trussess, so i will go with the 2x10's then to be sure?

rlk · Nov 21, 2003

Play it safe and use 2 x 12's on each side of the pole. They will cost a little more
but in the long run will be well worth the added expense.

Bob

dmccarty · Nov 22, 2003

mopower440,

Are you in a local that gets snow? Even here in NC we have
gotten as much as 24 inches of snow in the last couple of years.
There was a link the a NY state report on pole barn failures.
The report has a table showing the weight of snow per foot. I
was figuring 30#/foot for the live load on my barn roof. After
reading the study I'm going to at least 40#.

I just went and changed the number of column/poles so that
on the load bearing walls the pole are 8 feet OC instead of
12 feet. I did this BEFORE I read the report mainly due to
future siding and garage door issues. AFTER reading the report
I'm glad I put in more poles.

I have not rerun the load numbers for higher snow loads but
I think I'll be ok with using two 2x12. But I might go to three
2x12 to make sure. For the price difference between a 2x10
and a 2x12 get the larger lumber.

Later,
Dan (Who is NOT a structural Enginerr but who plays one at
home ) McCarty