Free building II: erecting the trusses

November 8, 2009

The first afternoon I assembled seven of the eleven trusses. By that point I was exhausted from all of the bending. A couple of days later my body had adjusted and things went easily. Basically the truss consists of three interlocking sections of 3″ oval pipe and a long brace running across its width, reinforced by a triangle of shorter pipe sections at the centre of the truss.

Bolting things together with 1/4 X 3 1/2″ carriage bolts was not difficult, though I discovered a light rope and a sliding hitch helped with the fitting.

How I was going to support/hold down the trusses? A gravel pad is fine, but a light building could easily blow away. I explored two junk yards in search of inspiration, but found no solution which would not 1. cost the earth, 2. leave a lot of expensive steel rotting uselessly on the ground and 3. still require anchors.

I asked Peter Myers. My neighbour is a machinery expert and has a lifetime of experience with things related to metal work. “I wonder if that building could sit on steel fence posts?” Laconic as ever, Peter merely pointed to a piece of heavy pipe leaning against his bench. “A pipe driver? No, I thought I’d push them down with the loader.”

Peter broke his silence: “Take this. It works better.” On my second attempt I managed to lift the thing to my shoulder and transport it to my truck. The one my dad had I could at least lift. It was a piece of 2 1/2″ pipe with a plug welded onto one end and some weight inside. This one was much heavier.

My dad used to cache valuable scrap metal in and around the base of an old silo. Less valuable scrap made its way back the lane, its proximity to the silo an indication of my dad’s perception of its value and/or the likelihood of its eventual use.

Fortunately for me, steel fence posts seemed to be at the top of my dad’s scrap-iron hierarchy, because I found several dozen of them in perfect condition on my first peek into the silo pit.

Time for Peter’s pile driver. I grabbed it out of the truck and immediately it overbalanced and dropped to the ground. No damage to the truck. Ten toes still intact. Strange centre of gravity there.

The first post is the only one that won’t be wrong in some dimension, so I enjoyed driving it. The heavy pipe made short work of the packed limestone, even the coarse material underneath it. It just powered the steel t-bar through until it finally hit a boulder and would go no further, leaving about 40″ above ground. I wondered if that would do. It was certainly sturdy.

I quickly laid out a 20 X 40′ grid, using little green flags on wire posts to mark the location of each post. These markers work well on sod, but much less accurately on gravel. Nonetheless I persevered, and drove a few more posts before the driver overbalanced and crashed to the ground once too often and I called it a day.

By next morning I had thought the situation over and used the driver to start the remaining posts, but then pushed them down with my loader. This was more to my liking, even though it meant freezing my hands on the hydraulic controls while the loader did its thing, and I still had to finish each off with the hand driver, sitting down on the job was a welcome relief from jamming poles into the earth with a thirty-pound pile driver. Soon I had 23 posts neatly lined up as the foundation for my free garage. 23? Uh, the first corner turned out to be wrong, so I drove another post, but it didn’t go in very far before it hit a boulder. So I eventually decided to use the original post, 6″‘ too close to the other end, but firmly grounded. I would explain to Bet that the angled entrance is a feature to make parking easier in winter.

The moment of truth had come. I eased the loader over to the pile of trusses and balanced the horizontal part of one on the teeth of the loader. Up the assembly went until the tails hovered just above the grass. Here goes! As my wide load oscillated overhead, I eased the tractor onto the foundation pad and stopped at the far end. Now what?

The tractor’s bucket formed a “V” in which the support brace for the truss rested. It wasn’t about to fall down unless I did something drastic, so why not experiment? I hopped off the loader, grabbed the right tail of the truss, and lifted as hard as I could. Up it came and settled over the top of the post. The truss seemed to have eaten about a foot of the post and it didn’t look as if it would fall, so I tried the same thing on the other side. As soon as I lifted the left tail, the right slammed down as far as it could on its post. Another lift, assisted by a step ladder, and I was able to position this end over its post, as well. The trusses are quite flexible at this stage. Counting my fingers, I let it drop, only to have it stick a foot down, as well.

That’s what sledge hammers are for. A series of gentle taps on the post and the truss, and it was time to get the loader out of the way and let the thing thud into the gravel bed on both sides. It stood there, unwavering, without other support. Good stuff in those fence posts. Another six trusses went up before the novelty wore off and I realized I’d better put some braces on before the wind came up.

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