Raising Heavy Timbers
Traditional timber framers will make all their bents ahead of time, and have them stacked in the proper order, waiting for the big day when plenty of help is gathered together for the raising. Lots of bodies wielding poles, as seen in Fig. 2.17, lift the bent to vertical. The poles can also act as temporary stops to aid during the lifting process. Someone — usually the boss — checks the bent for plumb, as diagonal bracing is fastened.
Oftentimes, professional timber framing contractors hire a crane for the big day.
My experience over thirty years has been to raise posts individually, brace them with temporary diagonal supports, and then to raise the girts or girders one at a time. Usually, this involves just two to four people, as at the Earthwood addition, but, in the case of a 30-foot ten – by-ten at Log End Cave, eight people and a pick-up truck were involved in the installation.
Mark Powers, now building a Log End Cave type of home with very heavy rafters, and working mostly alone, says: "With some creative engineering, I’ve been able to raise all of my girders and rafters with my trusty Kubota 45-horsepower tractor with its quick-attach forks and bucket. I can’t imagine building the house without it."
At Earthwood, I had fun raising a fairly green 15-foot ten-by-twelve oak girder — probably over 700 pounds (318 kilos) in weight — to the top of the posts, aided by just one other helper. We accomplished the feat by raising an end of the timber with a lever, and slipping a concrete block under it, about 40 percent of the way along its length. Now lifting the other end was easy, as the overhanging 40 percent of the beam’s weight cancelled out another 40 percent of the weight at the lifting end. Again, we made a slightly higher block stack 40 percent of the way in from the new lifting end. We alternated our lifts back and forth, end to end, always adding a block or two to the low stack. After a couple of lifts, we rebuilt the block stack with criss-crossed block construction, for greater safety and stability. In short order, we had the beam up to height, and then, one end at a time, transferred its load onto the braced posts.
to structural — problem, and it could easily have been avoided. But as I have said before, heavy timber framing is forgiving, particularly if you are willing to forgive yourself once in a while.