ACADuser

CMU Walls & floor heights?

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Here in Florida we do a lot of CMU exterior walls. I suppose the strength & termite resistance is driving that
Anyway when you have 2, 3 & 4 story houses then floor to floor error (3/4")  adds up.
With a block wall 9'-4" common plate height and 16" common web truss the first floor plate height is 9'-4" of course. But adding another 9'-4" the plate height becomes 20'.
And 30'-8" is the 3rd floor.  So to add in the 3/4" plywood subfloor in the model or not?

I suppose the correct method is to make floor to ceiling heights 3/4" less.  (9'-3.75")

How do you address this problem?

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I assume the floor trusses are hung off the masonry wall on a ledger, correct? If so, set the exterior walls to hang the floor structure, then set the the floor levels to your 9'-4" increments:

cmu1.thumb.PNG.94c1324eb4c2b53cdc4884393338e098.PNGcmu2.thumb.PNG.73f1868c31de6d72c25cec76c65987e3.PNG

 

With this method the actual floor system doesn't matter. This is my normal method of working with cmu, tilt-up, panelized, etc.

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Thanks for the reply,

So do you set all the exterior wall to those settings? On the 2nd floor there are cantilevered area that get frame wills & a 3rd floor above that.

Also the interior bearing walls, will they honor that plate height?

 

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Wherever you have a floor cantilevered (like at a balcony projection) don't set the wall (or a portion of the wall) to hang:

cmu3.thumb.PNG.a21c61d939e8224aed39a9bb7c8d74bc.PNG

 

Interior bearing walls will not respect the bearing height - you need to drag them up manually:

cmu4.thumb.PNG.15ebfb8cfda6d0a9628aa2f6a3c3d729.PNG

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Thanks, but I was talking about bottom chord bearing for the interior walls.

I'll take a look tonight, it's a little crazy today here.

 

 

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Bottom chord bearing for the interior walls is no problem - you won't have to mess with the walls at all. Too easy.

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OK did a test run & you are correct. Thanks for pointing that out. I've not been using the wall setting correctly all this time.

 

 

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