can a laminated 2 x 12 span 40 ft?

Question

im trying to brace up some roof trusses in my pole barn that that was ordered wrong the truss co. told me i could run a beem down the middle but i need it to span at least 35 to 40 ft

i ordered them from lowes i told the saleperson i wanted to span 30 ft on 48 inch centers then i change the order for 5 ft on centers he didnt let the truess co know

the truss co said i could put a beam down the center of the truss but i dont want a buch of post i want the most open space possible

the pole barn is 30 x 48

Answer 1

2x12 WILL NOT WORK!!!! TO SAFELY CENTER SPAN 40' WITH 16" ON CENTER CROSS MEMBERS FOR A STANDARD ROOF YOU NEED TO USE 5 7/8" X 14 7/8" LAMINATED BEAM
*****THIS IS ONLY FOR RIDGE-LINE OF THE ROOF NOT ***** ***********FOR LOAD BEARING FLOORS OR WALLS***********

Answer 2

You need to supply more info. Is the roof going to be flat or pitched? If pitched, is it under a 3 in 12 slope or above a 3 in 12 slope? Also, what species and grade of lumber are you using? You didn't mention where you live but in the northeast the present code is usually around 40# Live Load (snow) and 15# Dead Load. A #2 grade douglas fir 2x10 spaced 24" o.c. has a max span (run) of 14' 8" if it is a minimum 3 pitch so I'm sure a 2x12 of the same species would be fine. A southern pine species 2x10 spaced 24" o.c. might be okay. Check with your local building department. (You pay their salaries with your taxes, use them) Remember if you're using 24" o.c. spacing you will need 5/8" plywood and have to use plywood clips on the joints. Compare your material costs and you may find that 16" o.c. 2 x 10's with 1/2" plywood is cheaper and a little less backbreaking. The important thing to remember is that you should always pull a building permit. It is for your protection. If you fail to follow the proper procedure in erecting a structure and somewhere down the road you have damage from weather, etc., then your insurance company can and probably will deny your claim. When you build something, you need to build it well. Building code is the minimum standard for whatever it applies to. A good builder will almost always go above code requirements and build a good solid structure that will last for decades. EDIT: I'm not going to debate things with people who don't know what they're talking about or how to interpret charts right in front of them. Talk to your building inspector. Better yet, nail a piece of 3/8 plywood between 24" o.c. rafters and stand in the middle of it and see where you end up. A little knowledge can be a dangerous thing sometimes.

Answer 3

Laminated Beam Span

Answer 4

Without question you'll never find a 40 ft ANYTHING, but certainly you can splice 16's or 20's. The issue is more about supporting the span, not that you can make the span.

If you must have free space beneath, splice the 2 x by notching a fitting/joint/butt by cutting half away and bolting then use metal brace plates. You have to realize that at some point some compromise will occur in that wood shrinks and swells, bolts and plates rust, Holes enlarge and get sloppy just from movement of the structrure.

The fact that you state "ordered wrong" suggests "operator error" no offense, and demands the analogy, "measure twice, cut once."

Certainly the better choice will be to add a vertical support at any joint.

Steven Wolf
(The Rev.)

Answer 5

I do agree on both replies. I would make sure you get the truss engineered by the truss company so that your building inspector can see that. I kinda look at it to be an alteration to the truss, so you should have paper work approved from the truss company so your not liable and they are.

Answer 6

i would get the truss company to give me a letter and a drawing showing how they want it installed.......this way u will cover ur self!

if they r engineer roof trusses then follow their idea.....but to answer ur question, under normal conditions NO u can not span a LVL 12" 40 ft.......

lic. gn. contractor

Answer 7

The General statues,International Residential code,International
Building code all lead you to one solution for your problem.
A new plan Stamped and Signed by a Structural Engineer and
submitted the the Building Official for approval.

Answer 8

There are to many variables to tell you anything on this one.
You will need to have the truss company give you a detailed print on the needs for the trusses and what you will need to make them work as they are not the right ones for your needs.