Hi all,
I don’t have any shoring jacks, though I am getting some. In the meantime, I need to jack up a deck slightly while I install new posts and beam. It won’t be on jacks for long, just enough time to pull out the supports, and put the new wood into place (everything is pre-cut and footings are in place).
I’ve been on jobs where little bottle jacks have been used under a legth of 2x (probably doubled up, or set in a t-shape) to jack up a new interior beam into place. But the jack kicked out and that scared me pretty stupid.
Is there any way to jack with a bottle jack…and ensure it’s done safely without risk of kick-out?
Justin Fink – FHB Editorial
Your Friendly Neighborhood Remodelerator
Replies
Build a plywood baseplate for the jack. Scrap of plywood with scraps of lumber or ply to form a perimeter curb so the base doesn't slide out, then stake the baseplate to the ground. This will also provide a little wider base for the jack to help prevent it from sinking in the soil.
"Put your creed in your deed." Emerson
"When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it." T. Roosevelt
Ply will probably work for this little old deck, but for real jacking, youcan punch right through a plywood base. I usually use a couple of 6x6 a couple feet long, then another across it to set the jack on.
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I have a 12" x 16" piece of 1/2" steel plate that I put under the jack. Wood can crush before you reach the max load most bottle jacks can handle.
-- J.S.
Sure.
You first have to be sure that the base is on a firm level spot. I usually want a piece or th=ree of short cribbing to spread the laod.
It is being off plumb that makes things kick out usually. So if the base sinks into the ground, it will go off plumb and let it kick. use a couple cedar shims too if need be.
Then use a steel plate under the post you are jacking to, or the jack can act like a wood splitter. Be sure the jack stem is centered under the post, and that the post itself is plumb.
Getting all that lined up working alone can be tricky.
Get those relatives to help you help them...
if alone, get it all close and slightly loose. then you have to stand theere with post and level while you work the jack handle with your toe.
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as usual you give a precise & concise description...
I keep meaning to weld up a plate with lips with screw holes, and a short pipe piece on the bottom to capture the jack....I'll get to it one of these years....
Better yet, a house mover I know simply welded the base of some of his jacks to larger steel plates. Pre drilled the larger plate for nails/screws so he can fasten it to his cribbing.
"Poor is not the person who has too little, but the person who craves more."...Seneca
I use cribbing preferably 6x6 sections at least 3-4' long, with a platform on top of the cribbing made from 6x6's also. I use jacking plates made from 1/2" steel on top of the jack, as it's easy to punch a jack through wood.
OPD
Also, most hydraulics can bleed off over time, so unless this is just for an hour or two, cut another kicker to stand in next to it overnite so the load can settle onto something.
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Thanks for the tips, all. I guess seeing a tall LVL come slamming down right next to you can leave a mark, if only mentally!
Anything to be said for somehow tying the top of the "jacking post" to the object being jacked? I was thinking of anchoring it, however temporarily to the underside of the deck structure. At least that would help keep it from kicking out the top as well. No?Justin Fink - FHB Editorial
Your Friendly Neighborhood Remodelerator
Yes a couple of duplex nails or some screws tacked in there so it doesn't slide can helpp a bit. That is actually more valuable when taking things down! Imagine your self bent over maybe even leaning on the post with one hand, and turning the release screw on the jack, then having the post go bye-bye....
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The only reasonable way to do this (jacking with a short screw or hydraulic bottle when the jack point is several feet in the air) is to build some sort of sturdy scaffold up to near the jack point and place the jack on that. After the jacking is done (or halfway up, if you're going a good distance), insert some cribbing between the scaffold and the jacked member, spaced wide enough to catch things if the scaffold should lurch slightly and the jack pop out.
It should be noted that the cheap adjustable-length screw jackposts that you can buy for about $20 at home centers are fully capable of jacking a load such as a deck or porch roof. You do need to carefully place them, though. The plate that the screw bears on should be nailed/screwed to a stout, flat board on the ground, and the other plate should be nailed/screwed to the jack point (with a scrap of wood between, generally, to spread the load and prevent bruising the structure). It is CRUCIAL that the scrap attached at the jack point is braced in both directions, so it can't rock out from under the structure.
The post is then inserted screw-end down and its length adjusted via the holes and pins to be at tight as possible while still allowing the fully screwed-in post to be placed. Then extend the screw until it's taut. Once the post is taut check the ends to be sure they're bearing right before continuing to jack.
Like Piffin said it's all in the setup. Get some scraps of 4x or 6x header, and lay those on the ground on carefully leveled spots. If the jack or the stick above it are out of plumb then it may kick out. Set your block on the ground then use a plumb bob or laser to find exactly where to put the jack.
Attach some steel or plywood to the top and bottom of the post you're using to jack with, so you won't split it. Also, don't use a 2x- 4x4 is a minimum for stability's sake, 4x6 is nice if it's taller than 8' or much of a load. If this is the same deck you posted pictures of earlier, it's not that much of a load really.
You should also do something to ensure that the deck can't fall far if the jack does kick out- like temporary posts attached to the rim joist or something. They can also act as jack stands once you jack up to your desired height- just put some blocking and shims under them.
zak
"When we build, let us think that we build forever. Let it not be for present delight nor for present use alone." --John Ruskin
"so it goes"
A while back I bought a couple little hydraulic scissor jacks on wheels labeled something like 1 1/2 ton.
I have found them to be invaluable in ease of use and serve a handle a variety of situations.
I keep one for outside dirtier use and the other I keep clean for interior stuff.
If I lost them I'd go replace them with the same.
However, if one designs to construct a dwelling-house, it behooves him to exercise a little Yankee shrewdness, lest after all he find himself in a workhouse, a labyrinth without a clue, a museum, an almshouse, a prison, or a splendid mausoleum instead.
Parolee # 53804
Edited 4/27/2007 10:14 pm ET by rez
When I rebuilt my victorian porch ( 25 by 10 feet) a couple of years ago and jacked up the roof I did a couple of things that worked well and might be of use.
To keep the top of the jacking post from moving, I screwed a cleat on the side of the roof box beam, with the bottom of the cleat cut with a 15 degree taper toward the box beam. The top of the jacking post had a slightly steeper taper (maybe 18 degrees) so that the upper end of the jacking post would stay snuggled against the box beam.
At the bottom I most often put the jack on a solid concrete block, 4 by 8 by 16 inches, which is large enough for most loads but small enough to easily shim. An important factor for stability at the jack is to minimize the distance that the piston comes out of the bottle. Do this by adjusting the length of the jacking post and the position of the cleat (if you use one) so that the jack starts taking a load as soon as you start jacking. A well aligned nine inch jack on a stable base that has it's piston extend for only an inch or so is unlikely to kick out.
If the jack is not lined up exactly right, when you start jacking, the jack will increase it's tilt in the direction that it is mis-aligned. To control this, I would place the jack next to a vertical support post and put a spacer such as a 1 foot piece of 2 by 12 between the jack and the post and lean the jack ever so slightly toward the post. When I would start jacking, the jack would lean into the spacer and was unlikely to go in some other uncontrolled direction.
Some of my jacking posts were up to 12 feet long. To get rigidity without too much weight, I used two rough cut 2 by 4's, screwed together in a "T" formation.
Hope some of this helps
A concrete block might work for just this deck, but I wouldn't want to jack much on a CMU at all. I have lifted some laods that would destroy a concrete block
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Very true. Wood will also crush a little and maybe even make some groaning sounds to tell you to back off. Concrete shatters instantly and without warning.
-- J.S.
John Sprung,
Over the years I have worked closely with several house movers/lifters and have asked them why they used Doug Fir for their cribbing instead of oak.
What they told me was that oak will fail without a warning sound where as Doug Fir always warns you that it is being stressed to far. The Oak is stronger but they consider it more dangerous to use.
Just thought I would toss that out here.
"Poor is not the person who has too little, but the person who craves more."...Seneca
That's interesting. I never even considered oak. In fact, around here I've never even seen pieces of oak big enough. If you could find them, they'd be way too expensive for cribbing. Here, oak is strictly a high end furniture, floor, and finish carpentry material.
-- J.S.
Oak would be too expensive and too heavy to handle for cribbing too. Mine is all doug fir and spruce. The spruce is light and easy to handle and stacks cribs well, and the fir is better for spanning gaps or immediately under the jack. I also have a few cypres 8x8s from older demo jobs that used to be posts under houses. Those have been good for ground contact positions
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You guys don't have a sawmill down the road that will let you have all the 2-3' long oak/maple/hickory cribbing you can load in the truck?Admittedly most of my jacking is done in the mud under a broken machine, and usually the bottom layer of cribbing is permanently subterranian after the adventure.A medium to large guy named Alan, not an ambiguous female....
NOT that there is anything wrong with that.
We have a sawmill on every cornerbut not that many hardwood trees and what is harvested is too valuable for cribbing.And when you handle a pile the size of a truck ten times in a year, you want the lighter weight.
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Geez- you and Frenchy- rub it in why don't you! Sawmill on every corner...Even the ones around here run by Mennonites know the value of any piece of hardwood that your guys might give you for a song- we'd be paying large for it.
Well, I might not go to the extreme frenchy does, but I know the sawmill guy pretty well, and we are only talking about ends and scraps from making ties and pallet wood.He keeps a pile of scrap around for the neighbors, and when it gets too big, some of it goes in the chipper.Usually get a free load of bark mulch in the summer also, but he's beginning to get a market for that so I may have to pay now.A medium to large guy named Alan, not an ambiguous female....
NOT that there is anything wrong with that.
Make sure you have some redundancy. Don't rely on one jack, don't replace all the supports at once unless you have to, and make sure that you're never in harm's way- if you have to be under the load for an extended period while it's on the jacks, set up some secondary supports that will catch the load before it lands on your head should the jack let go or pop out. Remember, most of those jacks come from China these days...
I'm happy to report that the jacking went without problems. New posts and beam are in place, pictures to come.
thanks for the advice everybody!Justin Fink - FHB Editorial
Your Friendly Neighborhood Remodelerator
i had to cut down a big tree that was leaning the wrong way once, We could not wedge or pull it over, I cut in a spot for a little bottle jack and put a metal piece on top, That jack jacked that whole tree over, i still cant believe it