SPAX® PowerLags® T-Star Washer Head Wood Lag Screws

Base Part #: 458182()

Choose SPAX® PowerLags® T-Star Washer Head Wood Lag Screws. The low-profile, large diameter head design provides outstanding clamping force and improved aesthetics. Deep T-Star drive offers excellent bit engagement without requiring a “special” driver bit. Available in 1/4", 5/16”, and 3/8” diameters, and in lengths up to 10”. Buy SPAX T-Star Washer Head PowerLags and wood lag screws with HCR® high corrosion-resistant coating in bulk pails or in job-friendly package quantities (hex driver included) from wholesalers, dealers, and specialty distributors or retail hardware and home improvement stores near you.


SPAX® T-Star Washer Head construction fasteners with HCR® coating are intended for wood-to-wood connections in exterior structural applications when attaching treated lumber components. These fasteners are designed with a low profile large diameter wafer head for applications requiring additional surface area under the head for superior pull-down force. Ideal for deck ledger attachment and multi-ply beam applications.

Material & Coating

Cold-rolled “carbon steel” wire heat treated to Grade 5 durability and plated with an HCR® (High Corrosion Resistance) double barrier coating. “HCR” is tested and recognized for use in ground contact pressure treated lumber for exterior, freshwater general construction applications (e.g. AWPA UC1-UC4A, UCFA)


SPAX PowerLags require no pre-drilling and drive faster and easier than conventional lags and other structural lag screws. We offer the largest selection of code-recognized structural wood-to-wood fasteners in the industry. Featuring SPAX patented thread technology and HCR high corrosion resistant coating, our T-Star washer head and PowerLags collection can be used for interior or exterior applications, including treated lumber.

  • IRC / IBC Code Compliant DrJ TER No. 1912-07 Structural Fastener Properties
  • DrJ Technical Evaluation Reports (TER No. 1711-01; Deck Ledger Attachment and TER No. 1802-03; Multi-Ply; Sawn lumber assemblies and engineered wood - LVL, PSL and LSL assemblies)
  • Grade 5 durability
  • No pre-drilling required (1/4" and 5/16")
    Note: Lead hole of 11/64" (0.172") diameter is required for 3/8"
  • Patented thread serrations require up to 40% less driving torque to increase installation speed while helping prevent cracking in logs
  • Built-on washer head designs eliminate the need and extra cost of a separate washer
  • Fastener length stamp on the head provides convenient identification without measuring and aids on-site inspections

Choose SPAX PowerLags structural wood to wood screws with built-on washer design in a variety of screw styles, including Hex head, T-Star, and multiple coating options. Request a sample pack of SPAX PowerLags today and build strong connections on the job site. Need something stronger? Shop our PowerLags collection designed for timber frame and log home construction.


• Multi-ply LVL beam assembly

• Multi-ply girder truss assembly

• Exterior treated lumber pergolas & gazebos

• Landscaping timber

• Outdoor furniture

• Exterior fencing posts

• Exterior out buildings

• Deck ledger to residential band joist attachment

For CAD documents, please see Technical Documents.

SizeDrive/Bit SizeThreadAvailable Pkg. Options
Retail PaxLarge Retail Pax1 lb. Box3 lb. Box5 lb. BoxIndividualProject PaxContractor PaxBulk Pail
1/4" x 2-1/2"T-30Partial1+1250500
1/4" x 3"T-30Partial1+1250500
1/4" x 3-1/2"T-30Partial1+1250500
1/4" x 4"T-30Partial1+1250500
1/4" x 4-1/2"T-30Partial1+1250500
1/4" x 5"T-30Partial1+1250500
1/4" x 6"T-30Partial1+1250500
5/16" x 3"T-40Partial1+1250250
5/16" x 3-1/2"T-40Partial1+1250250
5/16" x 4"T-40Partial1+1250250
5/16" x 4-1/2"T-40Partial1+1250250
5/16" x 5"T-40Partial1+1250250
5/16" x 6"T-40Partial1+1250250
5/16" x 6-3/4"T-40Partial50250
5/16" x 8"T-40Partial1+1250150
5/16" x 10"T-40Partial1+1250150
5/16" x 12"T-40Partial1+50150
3/8" x 5"T-50Partial1+1225150
3/8" x 6"T-50Partial1+1225150
3/8" x 8"T-50Partial1+150
3/8" x 10"T-50Partial1+150