Tricky trusses

My architect, Paul, originally called from the pitched roof to be supported by timber beams and posts. I didn't like the idea of posts since I figured they would get in the way of our equipment. I did love the idea of timber and suggested we use a scissor truss.

Scissor truss

I found a company in Perth, Gibson Timber Frames, that could make them. Unfortunately, the price was beyond my budget so I started to look at different options. While surfing the web, I came across a design known as a composite truss which uses steel rods for the lower truss members. The rods are tightened with a left and right turnbuckle. I found this a much more elegant design and hoped it would save me money.


Neither Gibson or my engineers had done a composite truss so it took weeks of persuasion to have them consider it. Once they came up with a design, I had to source the parts. The steel rods are connected to large steel plates inserted into the timbers. I found a company in Carp that could make the plates but they couldn't rust proof them. So I found another company in the east end of Ottawa (Zincon) to coat the plates in zinc. I couldn't find anyone local to supply the rods and I ended up ordering them from Portland Bolt in Oregon. The stainless steel bolts were custom ordered from Fastenall. I was counting on five different suppliers delivering correctly and on time. A big gamble but Paul had modeled all the parts in AutoCAD and was confident it would work.

Today, the gamble was put to the test. Gibson delivered the timbers and we started to assemble them. Not an easy task given each timber weights over 500 pounds. But with four people we were able to move them and the pieces started to come together. The steel plates fit as planed with the help of a sledge hammer. The rods lengths were right on and the turnbuckles worked as advertised. We uncovered a couple mistakes. Gibson forgot one of the trusses and worked overnight to deliver the missing one. I ordered the wrong number of bolts but luckily was able to get more delivered the next day. My friend Pat and his son Conor dropped by to watch and I put them to work assembling the trusses. As we finished preparing a truss, Perry used a crane to lift it into position. The trusses were to sit in a saddle at the top of the steel post. Holes were pre drilled in both the steel saddle and trusses for the bolts. After lowering the truss into place, Perry was having trouble inserting the bolts. He discovered that the solder joint in the steel saddle was the culprit so we chamfered the edge of the timber and the holes aligned. Things went smoothly after this adjustment and the trusses were in place by the end of the day.