Barn Raising - Part 4
Blow-By-Blow
Okay, you saw the first two trusses just "go up" in the previous page.
For the third truss, we have enough photos to give you a blow-by-blow accounting
of just how we get these things vertical and positioned. Realize
that these trusses are nearly 24 feet wide, 20 feet high, and weigh nearly
800 pounds each. Getting them raised and positioned is not trivial;
especially if one is concerned about the safety of the people, equipment,
and the truss itself. It took a lot of brainstorming, geeking, and
negotiating back & forth to come up with a plan that got the trusses
raised without killing anyone (and make no mistake; even with hard hats
a fatal accident was not outside the realm of possibility).
Step 1 - After assembling the truss, four ropes are attached to
the peak -- two fore, two aft. The majority of people get on the
ropes and get ready to haul on command. A small crew lifts the peak
of the truss onto the loader bucket. The feet of the truss are braced
against the piers to serve as a pivot point.
Rosie then very carefully lifts the truss up and inches
forward, tipping it up as far as she can.
The "pole people" on each corner of the truss then push the truss
off the loader bucket, at which point the aft rope crew hauls the truss
upright. Once it is upright. all rope crews apply tension to keep
it that way. At this point the truss is vertical, but in front
of its pier. To lift it onto the pier, Rosie positions the loader
bucket under a chain that has been slung across the truss uprights.
This is the most hazardous part of the operation; Rosie lifts the
truss up by the chain, and a crew at each foot wrestles it onto the bolts.
What makes this so dangerous is the fact that the chain is holding the
truss up well under its center of gravity. It is absolutely
critical that the rope crews apply sufficient tension in both directions
to keep the truss upright during this operation; otherwise, it could very
easily tip over and crash into the building, the backhoe, or an unlucky
person.
Once the truss is in place, the worker-with-the-wrench quickly
comes in and sets the nuts onto the bolts, thus assuring a minimal
amount of stability for the truss. Still, we keep tension on the
ropes until the girts are in to hold the truss up to the rest of the building.
With the truss secured, Rosie gently backs away, and we're on our
own!
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