ThruLok screw-in bolts replace 1/2 in. through-bolts
FastenMaster just introduced an innovative screw-in bolt that replaces ½ in. through bolts called a ThruLok that I think deck builders will warm up to quickly. No need to bore a bolt hole, you just chuck the ThruLok head in a drill/driver and screw the bolt right through your wood to wood connection.
ThruLoks more or less replace ½ in. threaded bolts 3 to 2 – meaning 3 ThruLoks roughly match the strength of 2 – ½ in. bolts. Common uses are bolting posts to rim joists, beams to notched posts and posts to blocking. There are two technical bulletin links on the ThruLok web page detailing about a dozen different configurations using ThruLoks. ThruLoks come in 6 ¼ in., 7 in., and 8 in. lengths.
Installing a ThruLok is easy, you just have to follow some simple steps. Drive a ThruLok into the workpiece and stop about ¼ in. to 1/8 in. before the washer seats (photo). Then you spin the Hershey’s Kiss shaped nut finger-tight onto the screw threads poking through the other end (photo). Finish driving the ThruLok with the drill / driver until the washer snugs against the work. In the last few turns the bolt tightens into the nut and pulls the connection tightly together. Two small windows on the nut show a minimum engagement point so installers and building inspectors can make sure each ThruLok is securely attached for the rated capacity (photo).
I tested a dozen sample ThruLoks by attaching kiln-dried-after-treatment pressure treated southern pine 2×8’s to like-dried 4x4s. It took a few seconds for the drill points to carve into the extra dry SYP before the threads grabbed; but soon as they did, the ThruLoks drove through in half a minute. To shorten the delay in thread bite, I rapped a couple ThruLoks in ½ in. until the threads hit the wood. The threads engaged instantly when I started the drill / driver and zipped right through the wood.
According to the FastenMaster website, ThruLoks should be available at pro lumber dealers across the US so if they aren’t at yours yet – ask. Expect to pay $2.50 – $3.25 depending on length and quantity. So how does that compare to the cost of bolts? My local yard gets $3.15 for a 1/2 in. galvanized 6 in. bolt with washers and a nut. Figuring I’d need 3 ThruLoks to match 2 bolts, I’ll spend an extra buck on the ThruLoks but save more than that on the install labor since I don’t need to bore the holes.
Step 1: Drive ThruLok through work stopping 1/4 in. short of seating the washer.
Step 2: Install the nut finger-tight onto the end of the ThruLok
Step 3: Finish tightening the ThruLok until the washer seats to the work and the tip of the screw reaches past the MIN line in the nut window.
Post to beam connection.
Post to beam connection.