Author Topic: Post and Beam Connection  (Read 850 times)

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Offline Peter_Danube

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Post and Beam Connection
« on: July 25, 2018, 01:05:22 PM »
I am self-building a 20x32 wood framed shop in Delaware that will become a dedicated wood shop. I am modeling my design in SU and have some questions about post, beam, and joist connections. I have to run everything by an engineer first before I get a permit, and would like to get as many of the kinks worked out of my plan before I do.

The structure is a 1.5 story with shed dormers on both sides of the ridge. In from each gable end I am putting up attic storage that is eight feet deep that stops just before the shed dormer begins on both ends (the dormers are about 20' long). The joists that create this floor span the 20' width of the building and rest on a beam. By my calculations, that is a 3-2x10, 8+ feet long. One end is supported by 3-2x4s buried in the exterior wall framing. The other end is where I have the question. I don't really want posts in the middle of my shop, but to this point it seems unavoidable without unlimited cash. In my mind, the post that supports the beam will also extend up to the ridge where it will also support the structural ridge for the shed dormers. I believe that makes it about an 18' post which I don't believe I could find and/or would be allowed. The question is can I make up a post of 2x's that will catch the attic floor beam and also function to support the ridge beam? For instance, could I laminate 5 2x6s from the floor to the ridge?

As an FYI, the center portion of the shop is a 20x16 area that goes from the floor all the way to the ridge, so there's nothing above this part of it. The shed dormers allows this area to be filled with natural light and is where I'll do most of my projects. The 20x8 areas on both ends under the attic storage is for dedicated tools, finishing, and lumber storage.

The 10-foot 2x8 joists that make up these attic floors and rest midspan on the beam start atop the double plates on each outer wall. I don't want them to overlap on the beam if that can be avoided, but would rather have them but into each other. How could that be done so they are also secure on the beam?

Appreciate any feedback you are able to offer.

Peter Danube

Offline Don_P

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Re: Post and Beam Connection
« Reply #1 on: July 25, 2018, 02:41:24 PM »
run 20' tji or open web truss joists and avoid the beam.
The post can run from main floor to loft, and the begin another post from loft to ridge. but yes you can build up a post.

Offline akwoodchuck

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Re: Post and Beam Connection
« Reply #2 on: July 25, 2018, 07:59:59 PM »
yeah totally agree with Don...go 2x12x20' or so for your storage joists, trusses or rafter ties on your dormer....posts in the middle of a shop are a real buzzkill....
"The lyf so short, the craft so long to lerne."

Offline Don_P

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Re: Post and Beam Connection
« Reply #3 on: July 26, 2018, 02:42:01 AM »
and low lights  d*. I was thinking more about this, one more way. You could have a gang of 3 or 4 attic trusses stacked and fastened together at 8' inboard from each gable. Run a LVL ridgebeam between them to carry the shed rafters ad run floor joists from the gable endwalls to the girder truss' bottom chords.

Oh, you can also get and use 20' posts, likely engineer land but they are available.

Offline SouthernTier

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Re: Post and Beam Connection
« Reply #4 on: July 26, 2018, 05:29:31 AM »
I have something similar, but not identical.  I have a loft in half of my 22x28 cabin, the other half is open (cathedral ceiling).  The dormers I will have are in the loft half.  The part under the loft is not open, which is a difference.  I will have stair framing going up to the lower part of the post and those stairs will also be framed into an interior wall under the loft.  And under the girder from the post to the back gable is also a framed wall, but because it has three doors (closet under the stairs, bedroom door, and bedroom closet door), I went with double 7.25" LVLs for that girder.  I did lap the loft joists from this girder to the walls since that is what code requires.

So my post isn't really a 17' post, but rather a 7+' "buried" (in the sense it is incorporated into the stair and wall framing) post and a 9+' post atop that.  Therefore I believe the post stability calc only applies to the ~9' section. 

I thought a real long time about how to do this.  The objective was to have the both the loft girder supported and also have the last loft joist supported, but without just stacking a "stand alone" post on the loft floor which would pose fastening and compression perpendicular to the grain challenges.  I finally came up with this approach (note, the stairs aren't built yet - they will be in the middle of the picture):



I have 3 1.75x7.25 LVLs as a post to support the horizontal girder LVLs, but I notched them so three 1.75x5.5 LVLs can stack on top of those going up to the ridge beam.  The difference between the 7.25 and the 5.5 allows me to have a ledge to put the last of the loft joists there, too.  To tie it all together, I have one long 17' 7.25" LVL running the whole length.  These are all tied together with Simpson Strongtie structural screws (6.75" I believe) at their specified interval. 

Not a cheap solution, but it should work.  I probably could have gone with a 6x8 (lower) and a 6x6 (upper) of an appropriate species, but wasn't sure how to spec or source that, but it would have been less expensive, probably.  The other options presented above may be cheaper and more easily workable.
« Last Edit: July 26, 2018, 04:48:12 PM by SouthernTier »

 

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