We estimated the weight of the limb to be 4,500 lbs. There weren't any adjacent trees to rig the brush out of. The 1st thing we did was secure the butt end with a 5/8" DB to an arborist block, down to a GRCS.
We then removed as much brush (weight) as possible to lighten the load. We then constructed 2 "A" frames to place under each fork to support the limb and to prevent it from crushing the potting shed. We used dimensional lumber for the "A" frame. 4X4's, 2X6's and 5/8" steel bolts.
We were then able to cut beyond the roofline and put the tip weight on the "A" frames. Tag lines were also used to prevent the limb from side to side movement.
I had some similar work we did to a very large ash limb that fell on a house after H. Isabel in 2003.
We used a small crane, since the crane could only take small sections we had to keep the log stable as we cut and took sections away with the crane. It had several limbs that peirced through the deck but we added a few pieces of lumber to stabilize. I cut holes in the log for the lumber to wedge inside of it and nailed them.
First pic: Picture of lead that fell and cut through the roof, crane taking away first section from butt.
Smart. We've used support systems before during storm work too. Not fun, but is necessary sometimes. I never grabbed a photo, but will try to now! Great stuff, let's see more of the tricky stuff!
Only had to use an A-Frame support twice in over 40 years of tree work, but works great when needed. I have some pretty good diagrams of all the loads calculated, when I last used it, which I'll try and upload.
How many of you newer guys have had a chance to do this?
BTW, for those of you who don't know who Norm Harris is, you should check out some of his articles. He's a Master Rigger who truly know his stuff!