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Brace location

Started by mpuste, August 15, 2017, 03:20:54 PM

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mpuste

In most timber frames I see in the US, braces are located at the top of posts, such as between a post and plate.  The ability of the brace to prevent racking should be just as effective if it is located at the bottom of a post, such as between the post and sill, and by moving the brace down you can create more options for locating windows.  Are there other structural (or non-structural) reasons for choosing to locate braces at the top of posts?

Dave Shepard

I don't think the effectiveness would be nearly the same if the braces were at the bottom of the posts.
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Roger Nair

I admit that I have a bias towards plate to post braces but I have used both sill to post and sill to plate braces.  Long sill to plate bracing will be stronger and will require fewer braces to secure a frame and are very common in old barns in my area.  From a raising pov once a sill to post braces are set the frame is braced without resorting to temporary bracing.  Braces that tie to securely supported sills are rock solid, without flex.  sill to post braces do not pick up direct load as they would from plate to post braces that impart a steady side load to posts that can stress joints and can lead to breaking joints.  Frames that have plate to post braces are probably more ductile and that could be a long term advantage.  I have worked on frames that were broken by braces footed in sills, in those cases the barns were not well maintained for generations. 
An optimist believes this is the best of all possible worlds, the pessimist fears that the optimist is correct.--James Branch Cabell

Don P

I don't see a problem with it. A longer brace is better than a shorter one. Look at old European work and you'll see both used. Old balloon frames and earlier platform frames prior to let in bracing typically had sill to corner post bracing.

mpuste

Thanks everyone for the feedback.  A brace from sill to plate is something I had not considered and I have seen barns here in the Midwest with that construction.  One of the reasons I asked the question is because I have seen timbered buildings in Germany with braces located mostly below the windows.  I have heard that the design of those buildings was partially due to the lack of quality timber so the design may have been driven more by material availability than optimal strength or rigidity.

Dave Shepard

Did those German buildings have brick infill (fachwerk)?
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mpuste

I can't say for certain if they had brick infill but since the exterior (between timbers) was coated with plaster it is very possible.

Don P

Will you have some form of bracing sheathing? If so that will be where the load goes.

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