Rafter Crane 25 Ton

[Jannet Nevels]

Lastspring as we were peeling, sanding and painting the timbers for Underhill House, the question of how we would get the roof rafters up on top of the bents was often on our minds. In previous houses built by Whole Trees Architecture and Structures, rafters have been hoisted up by ingenuity and muscle power, but Underhill House is an extra story taller than any previous Whole Tree house.

I moved timbers from their resting place on the ground up onto saw horses for individual attention and back again many, many times, and often considered the danger of hand hoisting those logs up onto the roof. I breathed a sigh of relief when Bryan decided to use a crane.

Two rafters span the three bents. Michael was stationed on the south bent, Brad on the north and Bryan and Prairie manned the middle bent on which the two rafters meet. Prairie would cut each north rafter to fit flush against its southern counterpart and then each mated pair was drilled and either screwed or nailed to the beams.

Dan showed Doug how to tie a rope to the trailing end of each rafter to help guide them into position. On such a blustery day, this was doubly important in order to prevent rafters from swinging wildly over the vulnerable heads of the busy crew members who were often looking down at their work instead of up at the next swinging timber, which resembled a battering ram with wings.

In the afternoon, the wind picked up, making the flying rafters strain against the rope like a frisky puppy, and we had a couple of what looked like close calls to me, but everyone assured me they never felt it was too risky.

As the day wore on, the pace of progress slowed down. The temperature topped out at 92 degrees and the wind was gusting to over 40 mph. Everyone was hot and getting tired, and we all began to worry about running out of drinking water.

But the last rafter went on at about 4:30. It was a start-early and work-late day, and I really appreciated everyone sticking with it to the end. As the third to the last rafter was rising into the air, I hopped into the car and made the mile+ run to Ridgeway for some cold, local beer (Man Moon from New Glarus Brewery and Arena Premium from Lake Louey). We all gathered in the relatively cool, shady basement and shared some building horror stories while wetting our whistles.

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What about raising the entire building, less demo?, This would raise your headers at the same time. Brace to hold parrelell , some well placed jacks and up you go. I would Think a House Moving company might work with you on this.

If you went roof only as one peice , I would say some type of Purlin about 1/2 to 2/3rds up from plate to ridge. Nailed /lagged, maybe ledger or timber locks evry other rafter. Big crane (crane company should be able to tell you what size crane, and if they are comfortable with the job)with a spreader bar. Four penetrations in roof sheathing maybe eight feet in from each end. Straps around purlins and rafters.

The sheathing IF NAILED PROPERLY creates a pretty stiff system. I have never lifted any thing this size or with shingles installed. Checking that all rafter, ridge, collar tie connections are ROCK SOLID would be a good idea.

I would thinh rasing the whole thing would be cheaper too plus safer. Run "headers" along the outside walls with the paralell wals obviously level with one another but the perpendicular walls different by the depth of your lifting beams. lift the whole thing, put in prebuilt wall sections and lower it back down. Remember though that regardless of where you insert the wall sections, you are creating a hing point and you have to do something to counteract that by tying the new wal section to old with more than just nails or bolts through the plates. Your BI had better sign off on your plan but I woulld think plywood spanning the addition ON BOTH SIDES would be enough to counteract the hinge effect.

thanks for your thoughts. the shingles arein fine shape so i was thinking of saving them, although i 'm guessing thats an additional couple thousand pounds. the hinge point is a good one, the inside is unfinished so sheating that would be no problem, the outside is vinyl that i was hoping to leave pretty much intact so sheating that over the hinge point would be more of a pain.. the job is in illinois.i am goint to talk to a crane guy this week. thanks again

BTW, no matter how new the siding is, you are going to face a clearly noticeable stripe of new vinyl in that band. If you lift the whole building, you could use an alternative treatment on the bottom which would look much better such as a brick band or faux stone. Not sure what you would do at the top of a wall to hide a new section unless you put up a band board at that point and switch to shingles from that point up. That would look fine on the gable ends not sure how it would look with just a two foot band on the other sides.

Lifting the roof will involve a crane for likely two days you will also have to demo the garage doors and openers and deal with completely rebuilding that wall if the owner wants taller garage doors as well. If you lift the whole building the garage doors and openers can stay in place provided you secure them and they will get naturally taller when you ift the whole building requiring just another section to be added on.

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