# Joist Bracing/Blocking Q's



## epson (Jul 28, 2010)

Cross bridging is often specified on plans if joist span is over 8'. It gets nailed on top, the subfloor is installed, and then the bottom gets secured.


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## acerunner (Dec 16, 2009)

epson said:


> Cross bridging is often specified on plans if joist span is over 8'. It gets nailed on top, the subfloor is installed, and then the bottom gets secured.


you're thinking the metal bracing like this which would be difficult to work around:









what I have is the 2x4 bracing nailed to the side of the joists like this:









there are already a few that must have been knocked out by an electrician to run wires and were never replaced. I will be replacing those. But my remodel includes running a large duct through a joist bay that would be too large to use bracing. So my question is would that be ok? Maybe I can use strapping instead?


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## behrend (Jun 11, 2010)

Has anyone tried the IBS2000 bracing systems yet?


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## Gary in WA (Mar 11, 2009)

From your State Code: 
Prevent rotation (blocking or hangers at ends) ________________________ 2308.8.2
Blocking at intermediate supports __________________________________ 2308.8.2
Joists >2X12 blocked or bridged max 8ft O.C. ________________________ 2308.8.5
No notches middle 1/3 of span ____________________________________ 2308.8.2
Bored holes min 2in from top or bottom or other notch or hole ____________ 2308.8.2
http://docs.google.com/viewer?a=v&q...557f1r&sig=AHIEtbTD8uknkHDKWtwwh1W5lElSFXE4_w

Notches and holes, Page 2: http://arch.umd.edu/Tech/Structural...Wood_Products/Notching_&_Boring_Guide_A11.pdf

You don’t want a gap. Better to compress some of it with the rest meeting. No gap under floor: http://oikos.com/esb/38/floorinsulation.html

Gap metal or wood cross-bridging or it will squeek……

Gary


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## acerunner (Dec 16, 2009)

GBR in WA said:


> From your State Code:
> Prevent rotation (blocking or hangers at ends) ________________________ 2308.8.2
> Blocking at intermediate supports __________________________________ 2308.8.2
> Joists >2X12 blocked or bridged max 8ft O.C. ________________________ 2308.8.5
> ...


thanks.

so is that a no to running ducts in the joist space since bracing is required? This is what was suggested by HVAC sub. He wanted to run cold air return in joist space, or more accurately, use joist space as cold air return plenum and line it with sheet metal.So unless I can install bracing inside the sheet metal?

I understand notch/bore restrictions in joists and studs, but my question is if bores and notches in blocking & top/sill plates fall into these restrictions or if there are separate restrictions.


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## epson (Jul 28, 2010)

Actually acerunner I was talking about your second picture.


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## acerunner (Dec 16, 2009)

epson said:


> Actually acerunner I was talking about your second picture.


ok. when you said nailed to the top, I thought you meant top edge of the joist, where it will be sandwiched between joist and subfloor, which must be the metal type.


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## epson (Jul 28, 2010)

No problem


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## Gary in WA (Mar 11, 2009)

"so is that a no to running ducts in the joist space since bracing is required?" ------- Yes, I have seen the block removed and used for HVAC, many, many times. As long as it passes inspection. 

"So unless I can install bracing inside the sheet metal?"----- No, that would cause air turbulence. 

"I understand notch/bore restrictions in joists and studs, but my question is if bores and notches in blocking & top/sill plates fall into these restrictions or if there are separate restrictions." ------ No restrictions. Some science: http://books.google.com/books?id=DWsmAAAAMAAJ&pg=PA749&lpg=PA749&dq=bridging+to+strengthen+a+floor&source=bl&ots=it36ZbRj6b&sig=RsHU_VEi-ZM0lLAHq69yvvy8Iy8&hl=en&ei=MNHwSdekHZL0tQOA3Z3QCg&sa=X&oi=book_result&ct=result&resnum=4#v=onepage&q=drilling%20wood%20columns&f=false

Top plates: pp.15: http://www.awc.org/helpoutreach/ecourses/MAT106/MAT106eCourseV09-2007.pdf

Gary


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## epson (Jul 28, 2010)

What we have done and supplied in the past was use a 3’’ x 2’ x 1/4’’ thick plate with 6 holes either side to except ½’’ lag bolts and we had no issues as per your reference to page 15.


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## acerunner (Dec 16, 2009)

epson said:


> What we have done and supplied in the past was use a 3’’ x 2’ x 1/4’’ thick plate with 6 holes either side to except ½’’ lag bolts and we had no issues as per your reference to page 15.


1/4" is awfully thick. How do you install wall coverings in that area?


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## epson (Jul 28, 2010)

acerunner said:


> 1/4" is awfully thick. How do you install wall coverings in that area?


By using furring strips


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## acerunner (Dec 16, 2009)

GBR in WA said:


> Top plates: pp.15: http://www.awc.org/helpoutreach/ecourses/MAT106/MAT106eCourseV09-2007.pdf
> Gary


on page 21 of that doc. "And when wider studs are used it's important that they rest completely on a plate. The code requires for the plate to be at least as wide as the studs."

I have a few walls that are furred out around footings as shown in drawing below. Would that be a violation?


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## Gary in WA (Mar 11, 2009)

Are the walls bearing or just to add insulation behind and hide the concrete footing? How wide is the bottom plate?

Gary


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## acerunner (Dec 16, 2009)

GBR in WA said:


> Are the walls bearing or just to add insulation behind and hide the concrete footing? How wide is the bottom plate?
> 
> Gary


sorry, my drawing is obviously not to scale. This was done for non-bearing partition walls, and on walls to hide plumbing and footing. The bottom they used 2x2.


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## Gary in WA (Mar 11, 2009)

That will work as long as it passes Inspection.

Gary


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