truss size

[Pendragon]

I'm trying to find the best truss size and construction for a barn style storage shed.

My original plan called for 2x6 spanners with 2x4s along top, with 3 supports, that was at 14'. Now I'm going 16', and wondering if 2x6's will still be sufficient.

Should I stay with 2x6's or go to 2x8?
Should I try to find 16' 2x6's, or fashion two 8 footers together with an OSB plate on each joint?

I know 2x4 will span 12' using this config (and 3 trusses together are strong enough to pick up a small car, been there done that!). but 16 feet is a long way from 12 as far as roofs are concerned.

The attic area may be used for storage, so extra load bearing is a concern in this case.

I can make a scan of the current truss design if that would help.

[A_unique_name]

pre manufactured from a truss manufacturer. What you are talking about is stick framing. If you want these questions answered proceed to a local truss company.

[trance]

you should consider larger "floor joists" in your truss if you plan on doing attic storage.

1) if you buying trusses, contact the truss manufacturer and explain what you need & get suggestions from them

2) if you are site building it, and you are not trussing the attic, but rather using traditional stick framing, I think you are probably going to need 2x12 or larger if you want attic storage on a 16' span.

I'd think that you woudn't get much floor storage space in your attic if you use trusses.

go ahead and upload your design drawing

[Pendragon]

This was for a 2x6 going 14'

http://www.thehomeforums.com/cgi-bin/pendragon.cgi?showpic&pic=2x6x14-truss.jpg&page=1

What if I skip the attic storage, it's not critical, just would have been a nice bonus.

[trance]

Hi - I wouldn't call the sketch you made a truss - since the center 2 panels are not triangulated.

Actually, it's a sort of vierendeel truss, however I believe that this is more a traditionally framed (stick built) roof. Vierendeel trusses require moment (rigid) connections at the joints - which is not possible in wood.

If you go to this page:

http://www.alpeng.com/engineering_architectural_info.html

and click on the "Span Tables for Roof Truss" you will see designs for roof trusses - note that they don't have much area for storage because they are fully triangulated. they also list spans and sizes and loading possibilities.

good luck! :D

[Pendragon]

The original design that I am going off of was the same basic pattern but without the bottom chord, it was just 2x4 with OSB plates over each joint!

http://www.thehomeforums.com/cgi-bin/pendragon.cgi?showpic&pic=2x4-truss.jpg&page=1

(wow, didn't realize the image quality on that was so poor).

While that may meet code and design specs, I WILL NOT climb on that! I simply would never have trusted it to be strong enough and the only advantage I see is more headroom and slightly lower cost.

My design is essentially the same design I used on another building (at 12'), but without the 'barn' styling of the extra angle on each side. That building isn't using the attic for storage (it's fully enclosed, insulated and vented).

I'll keep investigating, I'm still a good ways away from construction.

After looking that page over, it looks like I could go 2x4 all the way and still be ok, but I think I will stick to the 2x6 bottom chord.

[grover]

One thing you can do is talk to a truss yard about the truss you're looking for, and get a price quote- for the effort involved in building the trusses yourself, you may find it's just far easier in the long run to have them delivered. (You might even talk to them about any returns- maybe they built some trusses for someone else 6" too short and they got returned; you could pick those up for a steal and build your shed around it!) And at the very least, they will give you a diagram of the truss design with all the critical dimensions labeled, which you could use to build them yourself, with numbers to back the design up.