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Strong-Drive® SDWF FLOOR-TO-FLOOR Screw 

The Strong-Drive SDWF Floor-to-Floor screw is designed to simplify the wind-uplift restraint connection while providing superior performance over the life of the structure. The unique design of the SDWF 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 Take-Up Washer (TUW™) plays a key role in the long-term performance of the SDWF when installed between the screw head 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 Simpson Strong-Tie® Strong-Drive SD Connector screws. The interlock between the tabs of the take-up washer and the threads under the head of the SDWF prevent the screw from sliding back under load, providing a simple yet reliable means of shrinkage compensation up to 3/4" per story.

Key Features

  • Faster to install than other floor-to-floor connection methods — drive the screw, install the take-up washer and the connection is made from plate-to-plate
  • Shrinkage compensation ensures a tight connection even after initial shrinkage and settlement occur
  • Installs from inside the structure, eliminating exterior work on upper stories and enhancing job safety
  • Fastening can be done before or after exterior sheathing is applied for added flexibility
  • One screw length can be used for multiple floor depths (refer to chart to select appropriate screw size), reducing the need for many screw lengths
  • Qualified for use in engineered wood products

Applications

  • Wind-uplift restraint connections

Product Includes

Kit includes all required installation hardware:

  • (25) Strong-Drive SDWF Floor-to-Floor screws
  • (25) TUW take-up washers (washer is galvanized 10 ga. steel)
  • (100) Strong-Drive SD Connector screws (#9)
  • 5/16" hex driver bit (replacement driver bit — BITHEXR516-R1
  • Screw depth guide to ensure proper SDWF engagement with TUW

Patent Information

  • US Patent 8,276,323

Related Literature

Fastening Systems Catalog
C-F-2023
A catalog including new product information as well as any applicable specification and installation instructions for Simpson Strong-Tie® fasteners and Quik Drive® systems.
Catalog
Fastening Systems Technical Guide
C-F-2023TECHSUP
A technical document featuring engineering information for structural fasteners featured in the C-F-2023 Fastening Systems Catalog.
Catalog
Guía técnica de los sistemas de sujeción
C-F-2023TECHSP
Un documento técnico información de ingeniería para los sujetadores estructurales que se incluyen en el C-F-2019SP Catálogo de sistemas de sujeción.
Catalog
Sistemas de sujeción
C-F-2023SP
Catálogo que incluye información sobre productos nuevos y las instrucciones de instalación y especificaciones correspondientes para los sujetadores Simpson Strong-Tie® y los sistemas Quik Drive®.
Catalog
Fastening Systems Technical Supplement for Canada
C-F-2017CANADD
A technical information addendum for Simpson Strong-Tie Fasteners in Canada.
Catalog
High Wind Guide
F-C-HWG23
A comprehensive guide to help designers select the most appropriate connections for high-wind regions.
Product Guide
Installer's Pocket Guide
S-C-INSTALL22
A bilingual pocket installation guide for connectors.
Product Guide
Fasteners Simplify Wind-Uplift Restraint
S-F-SDWFSDWC23
A sales flier explaining continuous load path implementations along with features, benefits and installation diagrams for the Strong-Drive® SDWF Floor-to-Floor and SDWC Truss screws.
Flier
Strong-Drive SDWF Floor-to-Floor screw
F-F-SDWFTUW21
A flier providing current product information for the Strong-Drive® SDWF Floor-to-Floor screw.
Flier
High-Wind Retrofit Solutions for Homeowners
S-C-HWRGUIDE22
A flier providing recommendations on reducing the risk of hurricane- and other wind-induced damage to existing homes.
Flier
Strong-Drive® SDWF FLOOR-TO-FLOOR Screw for Alternate Floor Joist Depths
L-F-SDWFALTHT22
This letter provides withdrawal loads and SDWF spacing for common floor depths which result in reduced thread penetration and are not included in our Wood Construction Connectors catalog tables.
Engineering Letter

Product Information Table

Fastener Production Information and Stuff & Things
Model No. Coating/Material Length (in.) Head Diameter (in.) Shank Diameter (in.) Drive Type Head Type Thread Type Thread Length (in.) Point Type Packaging Qty.
SDWF2716-TUW E-coat® Electrocoating 16 0.730 0.270 5/16 in. Hex Hex Washer Head Variable Thread Design 5 Type-17 Point 25
SDWF2720-TUW E-coat® Electrocoating 20 0.730 0.270 5/16 in. Hex Hex Washer Head Variable Thread Design 5 Type-17 Point 25
SDWF2724-TUW E-coat® Electrocoating 24 0.730 0.270 5/16 in. Hex Hex Washer Head Variable Thread Design 5 Type-17 Point 25
SDWF2726-TUW E-coat® Electrocoating 26 0.730 0.270 5/16 in. Hex Hex Washer Head Variable Thread Design 5 Type-17 Point 25
SDWF2730-TUW E-coat® Electrocoating 30 0.730 0.270 5/16 in. Hex Hex Washer Head Variable Thread Design 5 Type-17 Point 25

Product Information Table

Model No. Length (in.) Drive Type Head Diameter (in.) Head Type Thread Length Thread Type Shank Diameter (in.) Point Type Coating/Material Packaging Quantity UPC
SDWF2716-TUW 16 5/16 in. Hex 0.73 Hex Washer Head 5 Variable Thread Design 0.270 Type-17 Point E-Coat® Electrocoating 25 707392478805
SDWF2720-TUW 20 5/16 in. Hex 0.73 Hex Washer Head 5 Variable Thread Design 0.270 Type-17 Point E-Coat® Electrocoating 25 707392885405
SDWF2724-TUW 24 5/16 in. Hex 0.73 Hex Washer Head 5 Variable Thread Design 0.270 Type-17 Point E-Coat® Electrocoating 25 707392845904
SDWF2726-TUW 26 5/16 in. Hex 0.73 Hex Washer Head 5 Variable Thread Design 0.270 Type-17 Point E-Coat® Electrocoating 25 707392448709
SDWF2730-TUW 30 5/16 in. Hex 0.73 Hex Washer Head 5 Variable Thread Design 0.270 Type-17 Point E-Coat® Electrocoating 25 707392455813

Load Tables

Product Information and Withdrawal Loads

Size (in.) Model No. Thread Length (in.) Joist Depth Below (in.) Reference Allowable Withdrawal per Thread Penetration (lb./in.)
Single Bottom Plate Double Bottom Plate
Min. Max. Min. Max. SP DFL SPF
0.27 x 16 SDWF2716-TUW 5 8 1/2 10 1/2 6 7/8 9 295 250 180
0.27 x 20 SDWF2720-TUW 5 12 1/2 14 1/2 10 7/8 13
0.27 x 24 SDWF2724-TUW 5 16 1/2 18 1/2 14 7/8 17
0.27 x 26 SDWF2726-TUW 5 18 1/2 20 1/2 16 7/8 19
0.27 x 30 SDWF2730-TUW 5 22 1/2 24 1/2 20 7/8 23
  1. Allowable loads are for CD=1.0 and may be increased for load duration up to CD = 1.6.
  2. Joist depth listed based on the 3/4" subfloor and 3" of thread penetration into double top plates.

SDWF-TUW Floor-to-Floor Screw — On-Center Spacing for Uniform Uplift Loads

  1. Spacing listed based on lesser of: single bottom plate bending allowable load, single bottom plate deflection limited to spacing/240 and 1/4" max. for No. 2 grade lumber, screw allowable withdrawal load, and take-up washer allowable load.
  2. Withdrawal load is based on a CD = 1.6 and minimum 3" penetration into lower wall double top plates.
  3. Stud-to-plate connections are required to complete the load path. These connections shall not exceed the lesser of 48" o.c. or SDWF spacing.
  4. Spacing values listed for SP lumber consider base values adopted by AWC on June 1, 2012.

Concentrated Uplift Loads

Model No. Single SDWF-TUW Double SDWF-TUW
Allowable Tension Load (lb.) Deflection at Highest Allowable Load (in.) Allowable Tension Load (lb.) Deflection at Highest Allowable Load (in.)
SP DFL SPF SP DFL SPF
SDWF2716-TUW 1,410 1,200 865 0.095 2,270 2,125 1,730 0.142
SDWF2720-TUW
SDWF2724-TUW
SDWF2726-TUW
SDWF2730-TUW
  1. Allowable loads listed include a wood load duration factor of CD = 1.6 for wind or earthquake loading with no further increase allowed; reduce when other loads govern.
  2. Single and double SDWF-TUW applications listed are for concentrated load uplift restraint conditions (i.e., end of header, at girders, or at the end of shearwalls).

See additional Load Tables, Technical Data and Installation Instructions for the Strong-Drive® SDWF Floor-to-Floor screw.

Code Reports & Compliance

Drawings

PDF DWG DXF RFA IFC SAT

Related Products

Strong-Drive® SDWC™ TRUSS Screw
Strong-Drive® SDWC™ TRUSS Screw
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Wood Shrinkage Calculator
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