How to calculate LVL strength? Adding beams for storage.

[INTMD8]

I have a 36x47 Wick pole building and would like a bit of overhead storage from the front wall to the 2nd truss out.

What I would like to do is add 2 36ft long 1.75thick 14in height LVL beams next to the existing lower chords and frame it in and cover it with plywood.

I'm just looking for a bit of extra room for boxes/tires/etc. Nothing heavy like engines/transmissions.

Is this a possibility and how do I calculate the strength of the LVL's?

Thanks!

 

[JakeKohl]

This one is easy - go to the place they sell them and their application engineer will gladly crunch the numbers for you.

 

[theoldwizard1]

What I would like to do is add 2 36ft long 1.75thick 14in height LVL beams next to the existing lower chords and frame it in and cover it with plywood.

Curious. What is the spacing between the bottom chords ?

Secure the LVL to the truss so that they can not twist/roll.

 

[6768rogues]

It depends on the load you intend to put up there. To calculate any framing member, the intended load has to be known. There are assumed loads for residential first and second floors, commercial floors, parking garages, etc.
That said, I would not attach to the truss chord. Any floor calculation has a "baked in" allowance for deflection. Typically a floor is 1/360, which means for every 360 inches of span a deflection of 1 inch under load is permissible. In your 36 foot span, the allowable deflection would be over an inch. Forcing the bottom chord of your roof truss to deflect over an inch might cause a truss failure.

 

[INTMD8]

Thanks for the input guys. I don't really have a per sq/ft goal in terms of load. Would rather know what the max load is for what I intend to do and if it's worthwhile, stay within that range.

Trusses are 8ft spacing.

The seller of the LVL that I found was Mendards. There answer was they didn't know so it seems I should speak with someone else.

 

[INTMD8]

I spoke with the building manufacturer and he didn't think adding the LVL's would help much.

They said that when they have an order for a building that will have light storage in the trusses they reinforce the metal truss plates with 1/2 osb and glue as the wood construction of the trusses is strong enough but the metal plates would be the failure point.

 

[59bones]

As others have said, I would not attach to the bottom chord of the existing trusses. Trusses in "pole barns" are designed to the bare minimums. Often the bottom chords are designed for dead loads only and zero live loads.

If those 2 - 1 3/4" x 14" lvls were working by themselves and spanning 36' they would only be able to carry about 30-40 psf, certainly not enough for storage loads and definitely not engines! Deflection on a span like that could be significant, as much as an 2"!

That 36' span is the killer. When designing long span beams, headers, etc. it is the span (not the loads) that necessitates BIG structure.

I suggest you speak with an architect (like me) or an engineer to help you design a safe, efficient storage system.