Strong-Drive® SDWF FLOOR-TO-FLOOR Screw


The Simpson Strong-Tie® Strong-Drive® SDWF Floor-to-Floor screw is designed to simplify the floor-to-floor, wind-uplift restraint connection while providing superior performance over the life of the structure. The unique design of the Strong-Drive SDWF Floor-to-Floor screw enables it to attach upper and lower walls together from the top, spanning the floor system and providing an easy-to-install connection within the continuous uplift load path of the structure.

The innovative TUW take-up washer plays a key role in the long-term performance of the Strong-Drive SDWF Floor-to-Floor screw when installed between the screw and the sole plate of the upper floor. As the structure settles because of shrinkage and construction loading, the threaded portion under the head of the screw ratchets up through the tabs of the TUW, which is fastened with Strong-Drive SD Connector screws. The interlock between the tabs of the take-up washer and the threads under the head of the Strong-Drive SDWF Floor-to-Floor screw prevent the screw from sliding back under load, providing a simple yet reliable means of shrinkage compensation up to 3/4″ per story.



  • Faster to install than other methods – drive the screw and the connection is made
  • Shrinkage compensation ensures a tight connection even after initial shrinkage and settlement occur
  • Fastening can be done before or after exterior sheathing is applied for added flexibility
  • Installs from inside the structure, eliminating exterior work on the upper stories and enhancing job safety
  • The TUW take-up washer installs with (4) #9×2 1/2″ Strong-Drive® SD structural-connector screws (provided)

Material: SDWF – carbon steel, TUW – 10 gauge

Finish: SDWF—E-Coat™; TUW—Galvanized


  • Use all specified fasteners. See General Notes.
  • To choose the appropriate SDWF length, add 6″ to the joist size.
  • SDWF installs best with low-speed, high torque (200 in-lbs minimum) drill with a 5/16″ hex-head driver.
  • See details for minimum edge/end fastener distances.
  • To install:
    • Drive the SDWF into the upper-wall bottom plate vertically (90°± 2°), until the head is a minimum of 2″ above the plate.
    • Slide the TUW over the SDWF head and center.
    • Continue driving the SDWF until the washer head contacts the TUW tabs and bends them until they engage the shank of the SDWF directly under the head.
    • Secure the TUW to the upper-wall bottom plate with #9×2 1/2″ SD screws (provided)