Built up Beam Carrying Truss Load

[airman89]

I thought I would get on here and see what you all think before I go make a decision. I have a continuous beam (3ply 2x12) running the length of the house (60’) on top of posts (7-1/2’ O.C.) with the splices in the beam directly over the posts. The trusses have a clear span of 50’. Am I able to use OSB in between the laminations? The only reason I’m wondering is because of the kind of load I’m dealing with. I can’t find much in the IRC about it to read up on so I thought I would get some opinions on this beam before I go assembling it.

Thanks everyone.

Adam

 

[PCustoms]

Huh?

OSB between what laminations?

Is the mean in the basement and the trusses above a 1st floor?

Trusses shouldn't be transferring load to a center beam.

 

[Innovate1]

Why are you wanting to put OSB between the 2 x 12s (I don't think the word lamination would apply in this case)? That's usually done to make the total thickness match other things - perhaps that's why. The 2 x 12s should be fastened together so they share the load. This is typically done by multiple nails vertically and repeating that at fairly close intervals - something like 18-24". I think the OSB spacer allows more spring or "give" in the connection so the 2x12 closest to the truss hanger takes more of the load. A lot depends on the actual load supported. Hard to know without more detail such as are they attic trusses - that would add a lot of load. All the former assumes the trusses are hung with hangers from the side which I am just realizing may not be the case. If the trusses sit on top of the beam then I see no reason against the spacers as the truss would contact all the 2 x 12s and the load would be shared. Seems like a good place for microlams.

 

[airman89]

Sorry for the lack of details I posted this right after I woke up this morning.

I have a Barndominium build with 6x6 posts.
The OSB im referring to would be used in between the 2x plies for spacing to match the 6x6 posts. The beam is directly over the posts and not hung on the sides. Splices in the beam are directly over the posts. For the trusses, one truss will rest over a post, the next one will rest on the beam, the following one over a post and so on alternating. These are standard trusses not attic or scissor etc. we have a 20 psf snow load here and I’ll be running purlins with 1/2” OSB and standing seam roofing.

Thanks for the fast responses!

 

[BillK]

I think some pictures would really help. I am usually really good at visualizing things but I am totally lost on this one

 

[PCustoms]

I think some pictures would really help. I am usually really good at visualizing things but I am totally lost on this one

This

 

[Zen]

So, the trusses are spaced @ about 3.5' on center?

 

[Innovate1]

Given what you have described I don't see any problem with the spacers. Although it might be easier and less spacer material to just put the 2x together and put a spacer strip for the siding and whatever finish is on the inside on the sides of the beam.

 

[MovingAlong]

I have a continuous beam (3ply 2x12) running the length of the house (60’) on top of posts (7-1/2’ O.C.) with the splices in the beam directly over the posts. The trusses have a clear span of 50’. Am I able to use OSB in between the laminations? The only reason I’m wondering is because of the kind of load I’m dealing with. I can’t find much in the IRC about it to read up on so I thought I would get some opinions on this beam before I go assembling it.

Thanks everyone.

Adam

Your truss supplier should have an engineer on staff that will design them to your needs. Many full service lumber yards will have someone qualified to engineer these type of designs too. Consider getting qualified direction, not just anonymous opinions...

Wishing you only success!

 

[airman89]

I think some pictures would really help. I am usually really good at visualizing things but I am totally lost on this one

Sorry I’m not the best at describing things sometimes.. I can take a picture when I get out there today.

Given what you have described I don't see any problem with the spacers. Although it might be easier and less spacer material to just put the 2x together and put a spacer strip for the siding and whatever finish is on the inside on the sides of the beam.

That’s a good idea that would make things easier. If I were glueing the plies together would the OSB then add any strength to the beam that’s worth talking about? Or would it not be worth the trouble?

So, the trusses are spaced @ about 3.5' on center?

Yes the trusses are built for 4’ O.C. spacing and I’ll have them at 3.75’ O.C.

 

[The Tool Tyrant]

Even not knowing the species of wood your 2X12's are, you're fine. The trusses are only carrying 25' of roof load and the 2x12's are only spanning 7.5'. Just be sure to 'crown' (sight for bow, place high side up) the 2x12's before laminating them. I would also suggest some type of column cap connection (Simpson) between post and beam rather than just toe-nailing.

 

[Hank11]

The OSB spacers add nothing to the strength. If you want this built-up beam to act like a solid beam it takes a lot of fastening. There really should be some engineering behind this. Who came up with the plan?

it would probably be a good idea to add some diagonal bracing from the beam into the ceiling system above. This will help to prevent the beam from snaking. Like a backbone with the ribs. But you may not need that because we don’t really know what kind of load you’re gonna have. And that’s where engineering comes in.

 

[airman89]

Even not knowing the species of wood your 2X12's are, you're fine. The trusses are only carrying 25' of roof load and the 2x12's are only spanning 7.5'. Just be sure to 'crown' (sight for bow, place high side up) the 2x12's before laminating them. I would also suggest some type of column cap connection (Simpson) between post and beam rather than just toe-nailing.

Thanks for the tips. Yeah I have the Simpson caps up there for one side of the cap and the building department wanted me to use a 2x6 on the other side and through bolt it for the beam post connection.

The OSB spacers add nothing to the strength. If you want this built-up beam to act like a solid beam it takes a lot of fastening. There really should be some engineering behind this. Who came up with the plan?

it would probably be a good idea to add some diagonal bracing from the beam into the ceiling system above. This will help to prevent the beam from snaking. Like a backbone with the ribs. But you may not need that because we don’t really know what kind of load you’re gonna have. And that’s where engineering comes in.

Thanks for the info and tips. This is just my design. I am building my own house.

When you say diagonal bracing into the ceiling system do you mean knee bracing? I will have knee bracing installed.

So you don’t think the OSB will add strength on edge in between the plies being glued and nailed?

 

[Innovate1]

Thanks for the tips. Yeah I have the Simpson caps up there for one side of the cap and the building department wanted me to use a 2x6 on the other side and through bolt it for the beam post connection.

Thanks for the info and tips. This is just my design. I am building my own house.

When you say diagonal bracing into the ceiling system do you mean knee bracing? I will have knee bracing installed.

So you don’t think the OSB will add strength on edge in between the plies being glued and nailed?

Hank is right that the OSB adds very little to the strength - small enough it can be ignored. As far as fastening the layers together, glue doesn't add anything in this case (except maybe make you feel like you have done something good). Just nail them together so they can't bow individually and that's fine. The issue with bracing that was mentioned was to keep the beams from bowing sideways. Some diagonal bracing on the bottom of the trusses - say from the beam end on one truss horizontally at a 45 angle to the next truss. This ideally will be carried across the building to the center, a brace will be run down the center from end to end, and similar bracing will be done on the other side. Not sure I explained that clearly so page 12 here shows a drawing of something similar.
https://wwtams.com/wp-content/uploads/2020/03/permanent_truss_bracing.pdf

 

[Hank11]

snipped...

So you don’t think the OSB will add strength on edge in between the plies being glued and nailed?

No.
Might as well put some dried up oatmeal in there.

You should ask the truss manufacturer for recommendations.

Can you post a sketch of your plan showing where the beam goes?

 

[billconner]

Do you really need to pack them out - make them wider? Maybe just at column tops?

 

[jack stand]

So you don’t think the OSB will add strength on edge in between the plies being glued and nailed?

If you want the extra strength, use 1/2" plywood, cdx will be fine.
You'll need 8 sheets for this. I don't think this is excessive or overkill for the relatively little cost. Offset the plywood joints by 4' between the plys of 2x12.
50' is a "healthy" truss!

 

[Youngandfree]

Sorry I’m not the best at describing things sometimes.. I can take a picture when I get out there today.


That’s a good idea that would make things easier. If I were glueing the plies together would the OSB then add any strength to the beam that’s worth talking about? Or would it not be worth the trouble?

Yes the trusses are built for 4’ O.C. spacing and I’ll have them at 3.75’ O.C.

So the beam isn't actually built and installed yet is it?

 

[Youngandfree]

Thanks for the tips. Yeah I have the Simpson caps up there for one side of the cap and the building department wanted me to use a 2x6 on the other side and through bolt it for the beam post connection.

Thanks for the info and tips. This is just my design. I am building my own house.

When you say diagonal bracing into the ceiling system do you mean knee bracing? I will have knee bracing installed.

So you don’t think the OSB will add strength on edge in between the plies being glued and nailed?

Plywood would likely be better

 

[PCustoms]

I'm still lost where this beam is in relation to the trusses and what the beam is actually holding up.

We should figure that out before we worry about how the beam needs to be made

 

[billconner]

I think it's a header between to columns and supports one end of a truss. The live load is I believe is a little under 2000 and dead load - assuming a ceiling - half that.

 

[PCustoms]

I think it's a header between to columns and supports one end of a truss. The live load is I believe is a little under 2000 and dead load - assuming a ceiling - half that.

60'?

I can't picture how thered be a single beam supporting 50' wide trusses. I could see this as the outside we all of a pole barn.

 

[billconner]

That's what it is. What some call a truss carrier. 60 x 50 pole barn with poles 7 1/2 ft on center, trusses half that. I presume 15' 2x12s.

 

[airman89]

No.
Might as well put some dried up oatmeal in there.

You should ask the truss manufacturer for recommendations.

Can you post a sketch of your plan showing where the beam goes?

Sorry I just seen all of these replies. Yes I’ll sketch it up sometime today to show you.

Do you really need to pack them out - make them wider? Maybe just at column tops?

I wouldn’t necessarily need to pack them out because I used these brackets on top of the posts but I wanted to lean more towards a stronger beam (even if slightly) and making drywalling easier by already having a flush surface.

https://www.lowes.com/pd/Simpson-Strong-Tie-Steel-G185-Post-Cap-Common-6-in-Actual-5-in/3047267?store=264&cm_mmc=shp-_-c-_-prd-_-bdm-_-ggl-_-CRP_SHP_LIA_BDM_Online_C-D-_-3047267-_-local-_-0-_-0&gad_source=1&gbraid=0AAAAAD2B2W-bCtncSa-6K3XPID6A7Rgu3&gclid=EAIaIQobChMIi5fSo4ibiQMVLUT_AR2HLBqfEAQYBCABEgIKX_D_BwE&gclsrc=aw.ds

If you want the extra strength, use 1/2" plywood, cdx will be fine.
You'll need 8 sheets for this. I don't think this is excessive or overkill for the relatively little cost. Offset the plywood joints by 4' between the plys of 2x12.
50' is a "healthy" truss!

Thanks for the tip, yes I’ll happily use plywood instead of OSB. Yeah these 50’ trusses are some nice Amish built trusses. I was surprised the bottom cord wasn’t bigger than a 2x6 (2 splices) considering the 50’ clear span. I debated a beam supporting the center of the trusses to but they assured me I don’t need one.

So the beam isn't actually built and installed yet is it?

No the beam isn’t built yet, I only have the measurements for it. I still have to finish a few things but I’ll be starting it on Monday.

That's what it is. What some call a truss carrier. 60 x 50 pole barn with poles 7 1/2 ft on center, trusses half that. I presume 15' 2x12s.

Yes you’ve got it spot on, that’s exactly what I have.

 

[billconner]

I believe the 3 2x12s are more than adequate, and the 1/2 ply won't add much. I get wanting framing flush for drywall. Book shelf gifts below, with horizontal batt's? The brackets are for 5 1/2" beam? I'd put the ply or OSB on inner surface, not interspersed between 2x12s. If you didn't have the brackets, I'd use truss screws up through posts and rip a 2x into 1" thick pieces to take drywall.

 

[airman89]

I believe the 3 2x12s are more than adequate, and the 1/2 ply won't add much. I get wanting framing flush for drywall. Book shelf gifts below, with horizontal batt's? The brackets are for 5 1/2" beam? I'd put the ply or OSB on inner surface, not interspersed between 2x12s. If you didn't have the brackets, I'd use truss screws up through posts and rip a 2x into 1" thick pieces to take drywall.

Hey Bill, I actually did something that I regret now (probably never seen this before) but I built stick frame walls with mid span blocking inside of the posts that will be fully sheathed. Originally I did this because I have a 2nd floor in here and wanted the stick frame walls to support the 2nd floor. Local building codes approved me for it but later in the build, that building department was shut down and transferred to the county building department and they said no that I had to put the load for the second floor on the posts. So I hung beams in between the posts.

Anyway, I wish I would have just done the standard wall girts or bookshelf girts. I would have been done framing a long time ago.

The brackets can accommodate a thinner or wider beam actually because it is a 2 picece. But it is meant for a 5-1/2” post width. I like the idea of using the truss screws and getting rid of some brackets. I might try that with the header truss connection instead of hurricane ties.