0.275" x 4" Strong-Drive SDHR Combo-Head Screw - Zinc, Pkg 100 MST/HST Strap Ties Witness Hole: Visual check confirms

Witness Hole: Visual check confirms correct installation

For purlin anchorage

Designed with type 305 stainless steel for corrosion resistance

If you have a nominal joist measuring 3-1/2" x 5-1/2" you will need an APHH46 Decorative Heavy Joist Hanger

Designed for joist

0.275" x 4" Strong-Drive SDHR Combo-Head Screw - Zinc, Pkg 100 MST/HST Strap Ties Witness Hole: Visual check confirmsThe Simpson Strong Tie Strong Drive SDHR Combo Head Screw is made for serious wood projects like cross laminated timber (CLT), mass timber, and other big framing jobs. The unique combo head design gives you flexibility, with a choice to drive it with either a hex bit or a T40 6 lobe bit. A knurled shank helps lock the screw in place, and the sharp Type 17 point starts fast, reduces driving torque, and often eliminates the need for predrilling.