If you would like to know more about the brand new state-of-the-art seismic retrofit guideline, there are around 30 educational videos and web pages that you will find interesting. Just type ICC 1300 in the search box in the upper right.

Joist Blocking In Cantilevered Floor Joists

Some houses have cantilevers extending a few feet over the cripple wall.  In these cases, some kind of system needs to be developed to keep te floor joists from rolling over.  This video looks at a blocking system applicable to houses where the floor joists are supported by the cripple wall.  In cantilevered systems, the joists do not sit on top of the cripple wall so a different approach was developed by the retrofit guideline Vulnerability Based Retrofit Assessment And Retrofit of One and Two-Story Dwellings. 

This will often be a bay window, a love seat, or sometimes an extension of the kitchen.  It is very impost to give special attention to these areas of the house because the joists are cantilevered which makes it impossible to connect the floor to the top of the cripple wall.  The seismic retrofit guideline VulnerabilityBased Assessment And Retrofit Of One And Two Story Dwelling provides one way of doing this. Joist Blocking Drawing in Guideline Retrofit of One and Two Story Dwellings

Joist Blocking Detail in Vulnerability Based Seismic Retrofit of One And Two Story Dwellings

The connector Type G is the Simpson StrongTie LTP 4.  This is an adequate method except in order for it to work the top plates need to be joined together with nails extending through the lower top plate into the upper top plate.  That way when the LTP4 slides the upper on top of the lower top plate it will transfer that force into the lower top plate when the plywood is nailed.

Joist blocking drawing by structural engieer

Joist blocking detail by Thor Matteson

This is a unique system that relies on the strength of a glued connection rather that a nailed connection.  Generally glued plywood to framing connections are avoided because glue lacks the ductility of nails and might snap.  In some cases you don’t have a choice.

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