Tag Archives: hangers

A Truss Raising Challenge

A Truss Raising Challenge

STEVE in ST. MARIES writes:

“My question is about raising my trusses. I bought my building package when prices were rapidly rising, not knowing how high they would go. I was only able to afford a third of the building I wanted, but I had the engineer design it so I could attach the other two thirds of the building (the shop portion) at a later date. So the gable end is a 40′ span and the eave sidewalls are 24′. To make it a sturdy freestanding structure, the center trusses on the 24′ sides are tripled, with single trusses on each end. Also, the purlins are hangered from the center triple truss and rest on top of the endwall trusses. With the tripled truss in the center having full bearing on the posts, i don’t see a way to use a winch box in the center. FYI, when i say center I’m looking from the eave wall side. What I’m thinking is building the whole system on the ground, using winch boxes at the four corners, and using two genie crank lifts under the triple truss to handle the weight. since the posts on the gable ends are notched to the outside, I was thinking I could use partially sunk nails on the top of one gable truss to keep the purlins from sliding down the pitch even though the other end will be in the hangars on the center truss, and using nails on the bottom side of the purlins to keep the truss from leaning in or out as I lift with the winch boxes. when the whole assembly gets up where it needs to be, the one gable side and triple truss will slide into the post notches, and the other gable truss bottom chord can be pushed into place and the nails removed on the bottom of the purlins that are resting on it to get everything on layout. Is this too convoluted? Will this work? Is there a better way other than renting a forklift or boom truck, which aren’t options for me?”

I have been through St. Maries many times. It made for a great stop on motorcycle rides around Coeur d’Alene Lake. Way back (early 1900’s) my great grandparents had a store there in town (I have an awesome panoramic photo on my wall – looking North from town showing billowing smoke from 1910’s Great Fire).

Temporarily attach short pieces of 4×6 to one side of your triple truss bearing columns opposite truss notch (using 8 inch long TimberLoks or similar) so you can winch up the center set of trusses. You can (should) attach purlins in end bays to tops of end trusses with Simpson H-1 brackets or equal and solid block on top of the truss, between purlins, to prevent rotation. On the end away from the triple truss notch, don’t attach lower few purlins, so truss ends remain flexible.

With six winch boxes, you can now crank up all of your roof at once.


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!