The Retrofit Mudsill Connection

 

Screenshot at Sep 07 18-40-55

 

There are four ways to modify the framing so that the plywood is attached to the bolts.

 

 

 

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OLYMPUS DIGITAL CAMERA

 

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Photo: Block Split in an earthquake retrofit

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Another Split Block on a Cripple Wall Retrofit

 

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Appendix Chapter A3 Existing Building Code

los Angeles Retrofit Guidelins

 

Blocks and plywood

This is a construction detail that illustrates the nailed blocking method is similar to those found in other retrofit guidelines..

Standard Plan A

 

FEMA DR-493

 

SEATTLE’S PROJECT IMPACT

 

FEMA P-1100

 

 

 

 

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Which Method is Best?

 

Douglas Fir nail pull out is 77 pounds.

Redwood (either close grain or open grain) nail pull out is 56 pounds

In other words, nails in redwood will pull out 28% sooner than nails in Douglas Fir. For this reason, some designers recommend adding 25% more nails to the redwood.  Unfortunately, there has been no testing to confirm this.

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The footnote states the adjustment is 1 – (0.5-G). If G = 0.37 the specific gravity adjustment would be 1 – (0.5-0.37) = 0.87. You would also still need to apply all other applicable adjustment factors including SDPWS 4.3.3.