Step Three: Shear Transfer Ties (Attach Floor the Cripple Walls)

Figure 3 shows plywood bolted to the foundation.  Shear Transfer Ties prevent the floor from sliding on top of the bolted and plywood braced cripple wall.   do this.   Strong steel shear Transfer Ties made of steel attach the floor to the cripple wall.  This completes the final stage of a cripple wall to shear wall conversion.

THIS IS WHY EVERY SEISMIC RETROFIT MUST ATTACH THE FLOOR TO THE TOP OF THE PLYWOOD BRACED CRIPPLE WALL. THIS IS BY FAR THE MOST COMMON OMISSION WE SEE IN THE EXISTING RETROFITS WE EVALUATE

THIS HOUSE SLID OFF  THE BOLTED AND PLYWOOD BRACED CRIPPLE WALLS.  AN EFFECTIVE RETROFIT CONNECTS THE FLOOR AND THE BRACED CRIPPLE WALL TOGETHER.

  • All seismic retrofit guidelines require the installation of shear transfer ties.  Be sure you have the right one.  Many shear transfer ties on the market that don’t do anything at all. 

SHEAR TRANSFER TIES CREATE A COUNTER FORCE TO THE EARTHQUAKE FORCE STOPPING MOVEMENT OF THE FLOOR

THESE SHEAR TRANSFER TIES RESIST EARTHQUAKE MOVEMENT.  THESE ARE VITAL TO ANY EFFECTIVE WOOD FRAME HOME RETROFIT

 

Earthquake simulation testing on shear transfer ties tell us ow much resistance a particular shear transfer ties has.    Always check to see that you are using the highest strength shear transfer ties available

Below is another kind of Shear Transfer Ties, there are many others. 

Earthquake Force Being Resisted by Shear Transfer Ties

SHEAR TRANSFER TIES RESISTING THE EARTHQUAKE FORCE

Using Plywood Blocks for Shear Transfer Ties

In older homes, contractors on occasion did not install blocking between the joists.  This can cause the joists to roll over like dominoes.  Locks blocks prevent this.

Sometimes it is not possible to connect the floor to the floor joists with steel or plywood blocks in which case one must staple the plywood directly to the floor

STAPLING PLYWOOD DIRECTLY TO THE FLOOR IS SOMETIMES THE ONLY WAY TO CONNECT A SHEAR TO THE FLOOR IT IS TO RESTRAIN