Building a 24×32 workshop/barn with 1/2 story above. Last week we raised the first gable wall with Proctor wall jacks I picked up used. I tried to learn as much as I could, there was a recent FH article and Mike Smith’s generous contributions. I had the company instructions which I read numerous times. We were raising a 24′ long gable wall with 10/12pitch with a 4′ knee wall, topped out about 14-6, 2×6 framing, sheathed, 4×6 post for bearing ridge. Heavy. We got to jacking and despite my nervousness all was going well. The higher the wall got, the more the jacks wanted to slide down the gable rafter, and these guys are heavy. As we got the wall to vertical, the jacks were pushing more than I anticipated. Before we knew it the wall was going too far, and the stops at the top were not yet making contact because the jacks were out of position from sliding down. Freak out time, I don’t know how we saved it, there must have been an unseen hand helping out. We stopped it at about 3 ” out and managed to inch it back bit by bit. The wall jacks are amazing, but watch those gable walls. For the 2nd one , I set up a tall brace to stop the wall on the outside, brace to the ground and set braces to stop the jacks from sliding down. What a difference. I’m usually pretty cautious, but I think we came close to a real disaster cause I didn’t take that extra step.
Discussion Forum
Discussion Forum
Up Next
Video Shorts
Featured Story
Few people understand it. Nobody agrees what it is, how to learn about it, or who's responsible for it. It has never been more important
Featured Video
SawStop's Portable Tablesaw is Bigger and Better Than BeforeHighlights
"I have learned so much thanks to the searchable articles on the FHB website. I can confidently say that I expect to be a life-long subscriber." - M.K.
Replies
I can't picture what you're doing wrong, but it's definitely something. The only way the jacks can slide down the gable is if there is slack in the cable. Those cables should be razor taut as they're holding the entire weight of the whole gable.
Was it just one of them slipping? This can happen on gables if you don't have both jacks in exactly the same position. Because it's a gable, by moving the jack left or right, you're effectively changing the height of the wall that's being lifted, as far as the jack is concerned. So if one is lifting from a higher point than the other, then one jack will be doing all the work while the other just tries to keep up as they'll be lifting at different rates. This can cause the 'slow jack' to slide down the gable. This can also be very dangerous as all the weight is on only one jack.
Were your jacks set up square to the bottom plate, or square to the rafter?
The jacks will slide some as you get very near vertical. But that's normal as you've taken the weight of the wall off them at that point.
One other note: If you picked them up used, you might want to give them a tune up. It's been recommended to me to replace the cables yearly. Mine are currently three years old and I just ordered the parts to give them a complete overhaul this year including the winches.
Wall jacks are a wonderful tool, capable of doing an impossible amount of work. But they really need to be used correctly and taken care of properly. They don't leave a lot of room for error and the consequences can be catastrophic.
According to Proctor's instructions, as you get near vertical, let one jack lead a little and go slow. It seemed that at that point, the weight of the 23' jacks was doing more than the cables. On the 2nd one I extended a short stick next to the jack and it worked perfectly. THe jacks were square to the bottom plate.
These jacks weren't very used, but the guy I got them from tossed the wall stops and lifting brackets, said they were junk. After replacing those they cost me $ 700 for the pair.
Bruce, I think your wall jacks were significantly too tall for your application.
I'm thinking that you were rasining a gable end wall from on top of the second story deck. Correct?
One of the biggest advantages of using the type of wall jack that I used (Mac-Hoists) was that I could adjust the height of the wall jack by simply building a shorter pole and inserting it into the brackets. I'd be using a very short pole on a gable end wall such as I have described. I think the pole would be in the 12' range and I'd be using my framing square to quickly calculate the exact position to locate it. Our goal was to use a pole that was the exact length neede to raise the wall plumb without having any slack available that would let the wall lean out. Essentially, the wall would lock in very close to plumb.
IF you are using a pole that is significantly too long, it becomes imperative that you adequately plan on stopping the wall using other means. It sounds like you've figured that out. Our solution normally was to stop cranking when the wall was past it's heaviest point, but well before it got light and wanted to drag us all over the edge. We'd then prop the wall using a couple of short "safeties" (temp braces that were held by gravity) and then we'd install a couple of "holdbacks". When the two winches started cranking again, we'd have a couple of guys holding the wall back and not allowing it to get past plumb. If the wall jacks were significantly too tall, they would add a substantial tendency to push the wall over, so we rarely used poles that were too long. I always considered that a rookie mistake. Unfortunatly, I don't think the Proctor poles are adjustable.
blue
Our Skytrak is for sale. It has 500 hrs on it. We want 50k (you pay the freight) and we'll finance it. Drop me an email; it's a good buy.