ThruLOK Through-Bolt Replacement

The ThruLOK system can be used for applications including multi-ply beams, deck posts, carrying beams and more. It combines the strength of a through-bolted connection with the speed of a LOK fastener with no predrilling required.

ThruLOKs replace traditional carriage and through-bolts in applications ranging from 4½”– 8 ½”. Its three-part assembly includes a screw, featuring the patent-pending Paddle Point™, engineered washer and LOK-Nut. Other features include:

  • Installs with an 18 volt cordless drill
  • No drill bits or wrenches required
  • Galvanized coating meets IRC ACQ corrosion requirement
  • Lifetime performance guarantee

ThruLOK is code-compliant when attaching decking handrail posts and carrying beams. For ThruLOK technical information and drawings, see the Technical Docs section below. For technical documentation of all our structural wood screws, see our Technical Resources page.


ThruLOK vs. Through-Bolts

In this short comparison video, see how much time is saved installing a ThruLOK vs. a carriage or through-bolt.

ThruLOK Through Bolt Replacement

ThruLOK is a multi-purpose structural wood-to-wood fastener that replaces carriage or through bolts. It is perfect for specific applications such as multi-ply beams, girder trusses, deck posts and many places where a traditional carriage or through-bolt is used.

  • Sku Selections
  • Installation
  • Technical Docs
  • Purchase FM Products
ThruLOK SKU Selection Guide    
 6 1/4"   4 1/2" to 5 1/4"   4x4 deck posts to 2x rim joists connections  6 pc box  FMTHR614-6
 24 pc box  FMTHR614-24
 7"   5 1/4" to 6"   2x beams to a notched 6x6 post connections  6 pc box  FMTHR007-6
 24 pc box  FMTHR007-24
 8"   6 1/4" to 7"   4x4 posts to double rim joist or single rim joist and 2x blocking  6 pc box  FMTHR008-6
 24 pc box  FMTHR008-24
 9 1/2"   7 3/4" to 8 1/2"   2x beams to 6x6 post connections  100 pc bucket  FMTHR912B-100

Put the ThruLOK-Washer on the ThruLOK screw with the teeth of the washer facing away from the head of the fastener. No predrilling required when properly installed. Using a 1⁄2" high torque variable speed drill (18V if cordless), drive the ThruLOK until washer and hex head are just above the wood surface (approx 1⁄4") and point of screw protrudes out other side of connection. Thread the ThruLOK-Nut onto point of fastener. Hand tighten nut until flush with wood. Tighten screw with drill. Repeat to match code-compliant fastening pattern.

Using an Impact driver or high torque ½” variable speed drill (18V if cordless), drive the ThruLOK until the pre-installed washer and hex head are almost flush against the wood surface. On the opposite side, thread the ThruLOK nut onto the exposed point of the fastener and firmly hand tighten. Finish by driving the screw until washer and nut are snug.

NOTE: Point of fastener must engage in ThruLok-Nut to “MIN” line or beyond.

ICC-ES Report, ESR 1078

The ICC-ES Evaluation Report demonstrates to the installer and code official that our LOK fasteners comply with the most current building codes. This report also provides the engineer with critical values needed to design safe installations. Reports from ICC-ES are the most recognized reports used by code officials across the U.S. This document can be shared with code officials, engineers, architects and specifiers who may have questions regarding proper use or code compliance of LOK fasteners.

Technical Evaluation Reports (TERs)

TERs qualify for building official approval and are developed from test reports that comply with IBC Section 104.11.1

Technical Bulletins

FastenMaster technical bulletins are abridged versions of our TERs that demonstrate general guidelines and fastening patterns.

ThruLOK Deck Post Technical Bulletin

This file contains technical information on how to fasten this application in a code-compliant manner

ThruLOK Deck Post Technical Bulletin - Canadian Version

This file contains technical information on how to fasten this application in a code-compliant manner - Canadian version (both English and French)

ThruLOK Carrying Beam Technical Bulletin

This file contains technical information on how to fasten this application in a code-compliant manner

DWG Drawings

For use in CAD software

Catalog Pages

Product specific pages from our FastenMaster catalog.

Purchase FastenMaster Products

To find a dealer near you, click below:

Find a Dealer

To order online, visit one of our online partners: