# Question about Walls Dimensions

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I have a house that has an 8" CMU with a 4" brick veneer and 1" air gap for a foundation that is derived from the first floor which is the standard Siding 4.  The foundation is set to dimension to the outer layer of the 8"CMU and the first floor is set to dimension to the outside face of the stud

If you look at the attached test plan the foundation dimension doesn't seem to be correct.  The difference between the face of the stud to the face of the block should be 5" (4" brick + 1" air gap).  So taking the 30'-0" dimension across the top of the building subtract 10" (2 x brick and 2 x air gap) the length of the foundation should be 29'-2" (30' - 10") but it's 29'-2 7/8".

Can someone please let me know where the addition 7/8" is derived from?
Thanks
Alan

Test.plan

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English, after examining your plan, all I see is a plan that is following your orders in terms of the way you have the main layer set on the foundation walls and the default settings of dimensions.

Can someone please let me know where the addition 7/8" is derived from?

To get a cogent answer to that question you will have to speak to Dermot Dempsey, Dan Park or someone like that who knows "why" (they wrote the code for Chief Architect)

DJP

PS: I know it is sometimes vexing that the software does what it was designed to do and not what you think it should do but part of the process of mastering it is learning that lesson over and over again

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Your problem is that your upper walls are set to Foundation To Exterior Of Layer: OSB.  OSB is 7/16" thick.  7/16" x 2 = 7/8"

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Okay David I contacted tech support for it.

Alan

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Alan,

https://chieftalk.chiefarchitect.com/index.php?/topic/8759-wall-alignment/

I'm afraid Scott and David both may have misinformed you just a little. The dimensions are correct and it is very easy to see where they come from without talking to any programmers, there IS a way to get those walls to automatically align and build like you want them, and main layers are not all that come into play...specifically when the foundation is involved.

To fix the problem you are having with this particular plan (at least like I think you want it), set the upper walls to Foundation To Exterior Of Layer: Fir Stud 16" OC and then click Align With Wall Below.

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Michael

If you take a cross section of that wall you will see that the face of the OSB is aligned with the face of the brick allowing only the siding to be proud of the brick (as it would be in actual construction).  So the only difference between the Siding 4 wall and the foundation CMU is the stud and air gap -- a total of 5".

Doing what you suggested only makes the face of the OSB align with the face of the brick so now both the OSB and siding are proud of the brick.  It doesn't change the fact that the dimension difference should be the stud and the air gap -- 5"

Alan

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Michael

If you take a cross section of that wall you will see that the face of the OSB is aligned with the face of the brick allowing only the siding to be proud of the brick (as it would be in actual construction). So the only difference between the Siding 4 wall and the foundation CMU is the stud and air gap -- a total of 5".

Doing what you suggested only makes the face of the OSB align with the face of the brick so now both the OSB and siding are proud of the brick. It doesn't change the fact that the dimension difference should be the stud and the air gap -- 5"

Alan

Sounds like it's building like you want it then. I wasn't quite sure of how you wanted it built. No matter...that 7/8" is still coming from the thickness of your OSB. I'm away from my computer, but if I remember correctly, your upper walls are dimensioning to the face of FRAMING (excludes OSB).

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I just had an epiphany and can now see where the OSB comes into play.  If we actually build the foundation with the face of block to face of block at 29'-2⅞" then build two stud walls with applied 7/16" sheathing at each end and erect them so the faces of the OSB are aligned with the outside faces of the brick and pull a dimension from outside face of stud to outside face of stud it will be  29'-2⅞" + 4" brick + 1" air gap + 1" air gap + 4" brick less the sheathing (2x 7/16" ) = 30'-0".

I was forgetting that the OSB is flush with the brick so face of block to face of stud is 4" + 1" - 7/16" = 4-9/16".  So 30'-0" less 2 X 4-9/16" = 29'-2-⅞"

​So Michael you were right all along -- I just couldn't see it.

Thanks

Alan

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You're very welcome.  Glad you got it figured out : )

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