Lowering a roof

I have too much time on my hands tonight. I'm thinking about all of the projects I've been meaning to do.

I need help ciphering something. I have a cement pad by the grain bins where the drier used to sit. It is a slab about 15x35. The slab is covered with a really nice steel roof but it is on telephone poles about 20 feet above the slab. The poles are rotting off and it has started to lean both south and east. The roof is going to come down someday. If I could plant new posts and find a way to lower it without destroying it I would slap sides on it and use it to store a grain truck or even alfalfa.

So how can I lower it? It is high enough that none of the three loader tractors here could reach it. It isn't built in such a way that I could just support either side and cut off the posts. There isn't enough support to the roof. Forgot - there is currently a pole on each corner and one in the middle of the long sides.

A Scaffolding will hold a lot of load. You could build four towers out of scaffolding to safely support the four corners and support the roof while you replace the poles or build walls and not lower the roof. X brace between the four towers with cable and come-a-longs and you have a very stable structure. Scaffolding rents pretty cheaply by the month.

B To lower the roof you would need to come up with a jacking system to lower the roof controlled. One method is to build the walls you want with the scaffolding A above holding the roof. Then hire a crane for one day and lift the roof slightly while you remove scaffolding and let the roof down to the wall height.

C Without bringing in a crane, you can collect a lot of cribbing enough to crib all four corners the height of you scaffold sections. After you support the roof with scaffolding and get the poles out of the way, crib all the way from beams across the next lower scaffold section, then jack up 1/4 inch, remove one layer of cribbing, lower to the next lower level of cribbing and so on. Requires jacks that will travel al little more than your cribbing. 4x4 cribbing with 5 inch stroke jacks lets you walk it down four inches at a time. Takes a while but requires no expensive lifting equipment and the roof supported on four corners with 5 ft by 8 ft scaffold towers is stable.

D Set up six poles outside the roof, higher than the roof, with beams running under the roof to support the roof. X-brace the poles below the level you want to lower the roof to. Set up winches, or chainfalls on each pole to support the ends of the beams, like house movers. Lift the beams slightly, cut out old poles, install new poles or walls, then lower the chainfalls to let the roof down. Poles will hold against wind one direction, and x-bracing will hold against the other direction.

Just some ideas to chew on.

Set up some scaffolding or cribbing at the new desired roof height, then blow snow under it all winter 'til the pile will support the roof, then cut the poles off.

As the snow melts in the spring, it will gently lower the roof.

JUST think'in outside the box, here, but based on a tale in "POWER magazine" from any years ago by "Marmaduke Surfaceblow".

Every month there was a submitted story about how an operating engineer (or whatever) solved a tough problem somewhere in the world in the power generation industry. Steve Elonka wrote the column for many years.

In the case in point, a large steam engine was being assembled somewhere on the northern tundra, with GIANT flywheels and a crankshaft that needed to be lowered in place on the engine base, with big "pockets" in the floor to accommodate about 1/3 of the diameter of the flywheels.

No crane was available and getting the engine assembled and in operation ASAP was imperative.

The engine mfg. sent "Marmaduke" up there, probably by dogsled, and he solved the problem... had them cut blocks of ice and fill the recesses in the floor, then they rolled the crankshaft and flywheels into place, and as the ice melted the assemble was slowly lowered into the main bearings!

I can't immediately find a link to that very story, but the link below tells you what "he" was all about.
Marmy

We built a couple of 200,000 bbl oil tanks in Wood River a few years ago. One had a floating roof built close to the bottom and had to be raised to let the support legs be adjusted to low leg setting. Contractor proposed putting fans in the manways to lift the 200 ft diameter roof with air pressure. I didn't think company safety would go along with it, but they did. Very smooth operation, and air can't all leak out at once, so it was pretty safe. Lot's of ways to skin a cat. There's a little Marmaduke in all of us.

Safety first, a man can get killed trying to use front loaders way up high like that. I tried something like that, realized I was about to kill myself, and just got a local man with a crane. Simple, took no time at all, and I stood back and watched.

My sister has a boat dock on lake in Florida. We raised her roof using cables, pulleys and the electric boat hoist. Everyone thought it was a crazy idea, but it worked. Others tried doing what I did using jacks and their roofs landed in the lake. Her roof was supported by 6 poles. All the poles were cut half way up. All moved up slowly at the same time. Then we added spacer post. Added boards on all sides of post. Still standing years later. I wouldn't try doing it with front end loaders. Good luck.

Could you use grain bin jacks and lift it a little cut legs off then lower and repeat till its down to the correct height?

When I needed to shore up a corner of the foundation of my post and beam barn I needed of course to take the weight off with no good bearing surface available. I drilled two one inch holes through the post and using all thread I secured a piece of full 2x4 inch hardwood vertically to the post. This gave me a purchase point for my forklift. You could attach vertical pieces like I did to your posts, using as many through bolts as needed for the weight. Then use the verticals to rest on horizontal adequately beefy planks going out two feet to each side. This gives you a purchase point near the ground, so then you can take the weight off the posts with a little cribbing and a couple jacks. Then you could cut the deteriorated part off the poles, build a form and pour a concrete block with the steel attachments that they make to go into the concrete,to make a footing for each one, then lower the post back down to it. You could do them one at a time working safely on the ground. It would be a good idea to install two cable or chain safety braces from about ten feet down one post, diagonally up to the roof eaves member to eliminate the tendency that you say that it has now to lean. Once you have it on its new bearings you could install permanent wood or steel diagonal braces. If you think that this looks viable but is not entirely clear post back and maybe I can describe parts a little better.

Unless you can get a crane to lift the roof off I would dismantle the roof and start over. It's too dangerous to prop up and try to build a structure under it.

assuming it is a light roof--metal--and only 15 x 35. and the rot is at the bottom of the poles---consider bolting a heavy beam to the 3 poles on the 35 ft sides at a height that the loader bucket can reach easily--not too high--
then cutoff off bottoms of poles 1 ft at a time alternating sides

I would recommend just dismantling it piece by piece, putting in your new posts and then putting it back together. Seems to me it would be safer and easier. If it is already leaning at all significantly then you will not only have to lower it onto new posts but also move it laterally however far it has to go to get back to where it started. Unless you get a crane I can't think of a way to do that.
Zach

I have lowered buildings like the one poster stated. Attach cross supports on the current posts. I would think they are just rotted at the ground level. So go up to where they are good. Bolt a cross support across the end posts. You can use a channel iron,a 3x12,etc. Put the cross supports at a level above your final bottom but low enough for your loaders to lift the roof. Just lift it up and cut the post off and set lower it to the height you want.

I like the idea of the beams (mentioned by 2 responders), but making sure the balance stays correct, and all is safe worries me. My recommendation is to use a high lift style jack to raise the longest existing pole about an inch. cut 6 inches off the bottom and lower it. go to the next pole and do the same. Repeat this until they are all pretty even and the roof is close to level. Now build the posts and supports for the roof as needed next to the existing posts (make sure they are braced to plumb and stable). the again lift and cut old posts till it lands on the new structure. Tie the old to the new with splice plates and there it is. Jim

I can"t post pics of it, but we "saved" a shop roof by putting round bales on end on a semi flatbed, and backed it under the roof. Intended to drop the roof onto it, but the bales were too low, so we took out the old broken concrete floor, and hauled in clay fill- which was needed anyway. That raised the trailer to within a foot of the roof, so we pushed in the concrete walls and dropped the roof onto the hay. Roof was about 24x28.