Flat Washer Head Partially Threaded Structural Wood Screws, 4.0
  • Code Approval
  • ICC , ETA
  • Connection Type
  • Wood/Wood
  • Applications
  • Timber Framing , Log Home Building , Mass & Heavy Timber Construction
  • Manufacturer
  • SWG

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Flat Washer Head

Partially Threaded

Shank Cutter

Reamer Tip

Product Description

Product Description

The ASSY FWH 4.0 are partially threaded high performances structural fasteners. They are ICC-ESR [3179] approved fasteners, designed to pull connection elements tightly together.

They are two-in-one engineered screw that combines the pulling power of a washer-head screw with the clean finish of a countersunk head screw. Their design offers a precise setting without the need for pre-drilling [may be recommended for long models]. Their blue passivated zinc coating makes them adequate for use in low corrosive environment, such as dry service condition. They participate in LEED BD+C 2.0 certification [MRc 4.1 & 4.2, 2 points possible] thanks to the percentage of post-consumer recycled steel used to manufacture them.



Diameters  5/16″ (8 mm)
Lengths 4″ (100 mm)  to  15-3/4” (400 mm)
  • Partially threaded structural fasteners 4.0
  • Installed with RW Bits
  • Flat washer head for a clean architectural finish
  • Ideal for wood-to-wood connections
  • Blue passivated zinc coating
  • Reamer tip providing the fastest fastener wood bite & installation
  • Equipped with a shank cutter reducing the installation torque needed
  • LEED certification letter available upon request




SpecificationASSY F.W.H.Thread LengthDrive BitPackaging Qty.
# ItemMaterialHead
[4] FWH08080Hardened SteelFlat Washer Head5/16 x 3 1/88 x 80250RW 4050
[4] FWH08100Hardened SteelFlat Washer Head5/16 x 48 x 1003 1/880RW 4050
[4] FWH08160Hardened SteelFlat Washer Head5/16 x 6 1/48 x 1603 1/880RW 4050
[4] FWH08200Hardened SteelFlat Washer Head5/16 x 7 7/88 x 2003 1/880RW 4050
[4] FWH08240Hardened SteelFlat Washer Head5/16 x 9 1/28 x 2404100RW 4050
[4] FWH08300Hardened SteelFlat Washer Head5/16 x 11 7/88 x 3004100RW 4050
[4] FWH08360Hardened SteelFlat Washer Head5/16 x 14 1/48 x 3604100RW 4050
[4] FWH08400Hardened SteelFlat Washer Head5/16 x 15 3/48 x 4004100RW 4050
Design Guides

Design Guides

Structural Screw Catalog

A catalog with all information on our ICC & CCMC code-approved fasteners, including dimensions, references & design properties.

Code Approvals

Code Approvals

ICC Code Approval ESR-3179 for Partially Threaded Fasteners - 2022 Edition (October)

ISO 50001 Certification for ASSY Fasteners

White Papers

White Papers

Supplementary Considerations for the Conventional Yield Model

Screw Buckling Values for Compression Perpendicular to Grain Reinforcement

Withdrawal Resistances of ASSY Screws at Various Angles to the Grain

Technical Blogs

Technical Blogs

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