Tag Archives: Simpson

Simpson Strong-Drive SDWS Timber Screw

Simpson Strong-Drive® SDWS Timber Screw

In yesterday’s article I discussed attachment of roof trusses in post frame building construction. In most cases, Hansen Pole Buildings utilizes Simpson Strong-Drive® SDWS Timber screws.
It was more than twenty years ago Simpson Strong-Tie changed fastening world with introduction of a heavy-duty structural connector screw used in wood construction as an alternative to bolts. This screw, SDS or Strong-Drive® screw, was first screw of its kind able to be installed without predrilling and get loads comparable to bolts.

Simpson Strong-Drive® SDWS Timber screws have been newly redesigned for faster starts and less torque while driving.

They are designed to provide an easy-to-install, high-strength alternative to through-bolting and traditional lag screws. Strong-Drive® SDWS Timber screw proves ideal for both contractors and do-it-yourselfer alike. Code listed under AAPMO USE ER-192 it meets 2012 and 2015 IRC® (International Residential Code) and IBC® (International Building Code) requirements for several common wood framing and engineered-wood applications.

Photo: Simpson SDWS – Simpson Strong-Tie

A new patented point called SawTooth™ improves SDWS performance in two key respects. First it grabs wood, helping screw start fast and drive quickly. Occasionally, an installer runs into a piece of wood harder than others or engineered wood with a hard surface. When a hard surface condition becomes encountered, most screw points will spin around upon surface, grinding away wood fibers until one thread can finally catch and begin to cut in. Simpson designed this SawTooth™ point with a sharp angle and serrated threads to penetrate wood quickly. Threads begin to work right away, pulling screw in faster without frustration of waiting for point to scrape open a hole.

A bold thread design provides superior holding power. Under-head nibs offer greater control when seating screw head. Large low-profile washer head provides maximum bearing area (3/4” head diameter). All SDWS screw heads have a size identifier, making inspections easy. 6-lobe T-40 drive reduces driver-bit cam-outs, resulting in easier installations and longer bit life.

A second performance enhancement made to SDWS screws was to lower driving torque. Let’s face it, some of these screws are long, and you don’t want to have to fight to keep from being thrown by a drill. SawTooth™ point has a cutting knurl built into screw point. This helps open a hole in wood to receive threaded length of screw all while it’s being pulled in by threads. Having a thread top knurl helps reduce shank friction. Result – a screw driving with less wear and tear upon installer, drill motor or drill battery.

Double-barrier coating provides corrosion resistance equivalent to hot-dip galvanization, making it suitable for certain exterior and preservative treated wood applications.

Watch the video here: https://www.youtube.com/watch?v=VpZmjgz2ckE

Simpson Strong Tie

I believe in the use of engineered connectors, wherever they can be prudently used in post frame (pole building construction). The average consumer who has visited a lumber yard, or a big-box home improvement center has probably seen many of them, but may not have given them more than a passing thought.

About two decades ago, when I was constructing pole buildings, one of our clients called us after a freakishly high wind storm (significantly higher than the design Code required wind load, at the timSimpson Strongtie H1 Hangere, of 70 miles per hour) had plowed through their building. This particular building had 2×6 roof purlins on edge, cantilevered over the endwall roof truss, to support the end overhang. The wind literally tore the purlins off the end truss, and flipped the first bay of the roof upside down onto the second bay!

In doing forensic analysis, after the wind died down of course, we determined the connection of the purlins to the end truss with toenails was adequate to have withstood a Code wind load, but not the wind speeds which had attacked the building. The solution for the repair, as well as for future building designs was to utilize a Simpson H-1 bracket to attach overhanging roof purlins to end trusses.

Typical Hansen Pole Buildings utilize many engineered steel connectors manufactured by Simpson.  Most typically they include joist hangers to attach roof purlins and bottom chord bracing to interior trusses and strap hangers to attach X bracing to trusses as well as end trusses to columns in high wind load applications.

There is an interesting history to the development of Simpson brackets, which I had been unaware of:

“The Simpson Family has been in the San Francisco Bay Area building community since 1914, but it wasn’t until the mid-1950s that they launched the business that would become a world leader in their industry. And it all really began with a visit from a neighbor.

“The doorbell rang one Sunday night in 1956,” recalled Barclay Simpson, who took over a window screen business from his father in 1947. Outside was a neighbor who was looking to make structural connectors for the ends of 2x4s for a flat roof. Could Simpson help him out? “I said, ‘Of course’ and then tried to figure out whether I could.”

It was that request for a joist hanger that led to the creation of Simpson Strong-Tie, a global company with more than $550 million in sales worldwide (2010), more than 1,800 employees, and nine U.S. and 10 international manufacturing locations. As a publicly traded company, Simpson Manufacturing Co. has had exceptional performance records since the company’s 1994 IPO. As a result, it has consistently commanded the respect of industry analysts for its market leadership, strong fiscal management, and innovative approach to growth.”

My experience is, if an engineered steel connector exists, Simpson makes it – and if it doesn’t exist, their engineering team will find a solution!