Balloon Framed Wall Detail 2

[dhoward26]

Has anyone ever seen a detail like this before or done one? I am reviewing a design and don't know if this is a legitimate connection without seeing some sort of verification.

 

[dhoward26]

I guess I could probably just do a double top plat there as well, as that would span the 8ft between the Glulams.

 

[BAretired]

Yes, a double plate should be okay. Good solution.

BA

 

[dhengr]

The glulams should still be full height, and they do transmit fairly sizable reactions into the roof diaphragm and the floor diaph. or foundation. This is called “tall wall” framing. The wall panels btwn. the two exterior walls (shear walls under the eaves) and the glulams are supported, in good part, by the full height glulams. The sheathing transmits the shear in the plane of the wall, not the straps. The straps may act as tension ties across that platform framed double top plate, but as BA suggested, once the platform framing shrinks and settles, the straps will likely buckle under your sheathing or siding.

 

[ToadJones]

if you do this, I recommend that you put horizontal strapping on the inside walls if they are gyp board.

 

[dhoward26]

Thanks for the advice.

Reason for the straps:

Where the stairs come up, there is about 6'-4" of floor diaphragm to the wall for wind going the other direction. He has to transfer about 3000lb into the wall that I show with glulams with very little floor sheathing available (5'-0" wide x 6'-4" deep area to transfer through). He missed some special detailing at that location. The CS16 straps carry the tension load from the floor diaphragm into the wall. I showed them going full length so it would engage the entire wall. He still has some work to do on the detailing to transfer the load as it is decently complicated and was overlooked. Might be overkill to go full length, but CS16 straps aren't that expensive in the overall project, plus I would be able to sleep at night knowing there aren't any questions at that location.

 

[msquared48]

Looks good to me.

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[FSS]

I don't know what your wind loads are, but at first glance it looks like your "posts" will be overloaded with loads perpendicular to the wall. Those 4x12's are loading the posts right in the middle which can't be good. The full height LSL's just seem so much easier to build. Depending on your drawing scale, those scissor trusses can't be braced well and you need to go up to the roof diagram.

My two cents...

 

[dhoward26]

I originally tried a glulam in the center, but it WAS overloaded. Utilizing (2)glulam's I have quite a bit of capacity. I thought the load would be more than it is, but when accounting for tributary areas and 14psf wall wind loading, I only have about 1400 lbs total point load on the column. Deflection isn't the best, but my calc is a little conservative so I'm not too concerned about it.

I have in my red-line notes that full height LSL's are an option in lieu of the Glulam detail. I just think the Glulam detail with a double 2x8 (went with 2x8s to keep uniformity for the wall framing as the wall width is now governed by the glulam width) will be a lot less headache on the contractor for a few reasons: 1) LSL's are a pain to nail into, 2) it's fitting (2)-sticks of lumber full height instead of a bunch, 3) once the glulams are in place, the framers can frame just as usual and not have to worry so much about a very flemsy tall wall, 4) I don't know how much a stick of LSL costs these days but traditionally it has been much more expensive than DF.

 

[4thorns]

So....let me get this straight. Your detail considers:

1: Structural integrity...and
2: Ease of construction...and
3: The home owners wallet...

Number 1 is a given. I thought numbers 2 and 3 were lost years ago in a plague of self advancement.

Kudos