Foundation holddown placement

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Wayne Whitney - 26 Apr 2006 18:49 GMT

Hello,

A couple questions about the placement of foundation holddowns for use
with wood structural panel shear wall segments. First, for a 3" wide
holddown (e.g. Simpson HHDQ14) installed on a 3x6 squash post using 1"
threaded rod through a 2x6 mud sill, is it necessary to center the
holddown on the face of the post? Placing the holddown on the
interior side of the face of the post would typically better center
the threaded rod anchor in the foundation for greater strength at the
threaded rod/concrete connection.

Second, if there is space available on the outside face of the squash
post (the side not within the shear wall segment), is it OK to install
the holddown there? It seems desirable from the point of view of
reducing eccentricity, but perhaps there is some other reason not to
do this.

Thanks, Wayne

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Bob Morrison - 26 Apr 2006 22:17 GMT

In a previous post Wayne Whitney wrote...

> A couple questions about the placement of foundation holddowns for use
> with wood structural panel shear wall segments. First, for a 3" wide
[quoted text clipped - 4 lines]
> the threaded rod anchor in the foundation for greater strength at the
> threaded rod/concrete connection.

The placement you suggest is acceptable. You might consider a compromise:
fudge the HD a little closer to the inside edge of the stud, but not all
the way to the center of the concrete below.

> Second, if there is space available on the outside face of the squash
> post (the side not within the shear wall segment), is it OK to install
> the holddown there? It seems desirable from the point of view of
> reducing eccentricity, but perhaps there is some other reason not to
> do this.

Yes. The only "caveat" is that the trimmer studs must be securely
fastened to the full height studs. Another option is to use a through
bolt type HD or use longer SDS screws so that they capture all the framing
at the location in question.

Signature

Bob Morrison, PE, SE
R L Morrison Engineering Co
Structural & Civil Engineering
Poulsbo WA
bob at rlmorrisonengr dot com

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Wayne Whitney - 26 Apr 2006 23:20 GMT

> Yes. The only "caveat" is that the trimmer studs must be securely
> fastened to the full height studs. Another option is to use a
> through bolt type HD or use longer SDS screws so that they capture
> all the framing at the location in question.

Right, I hadn't considered this issue because in the locations in
question there are no trimmer studs (the squash post location is
determined by the presence of a larger opening above). I see that if
a trimmer stud is in the load path, then the trimmer stud must be
attached to the squash post (king stud) in a way that is at least as
strong as the holddown.

As to the original question, it's not a problem for a floor-to-floor
tie to be attached to the top of one face of a squash post and a
foundation holddown to be attached to the bottom of the opposite face
of the squash post?

Thanks, Wayne

Reply to this Message

Bob Morrison - 27 Apr 2006 01:11 GMT

In a previous post Wayne Whitney wrote...

> As to the original question, it's not a problem for a floor-to-floor
> tie to be attached to the top of one face of a squash post and a
> foundation holddown to be attached to the bottom of the opposite face
> of the squash post?

Shouldn't be a problem. that scenario actually has a tendency to minimize
the effect of the load eccentricities.

Signature

Bob Morrison, PE, SE
R L Morrison Engineering Co
Structural & Civil Engineering
Poulsbo WA
bob at rlmorrisonengr dot com

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Homeowner Forum / Construction / April 2006

Foundation holddown placement