Leveling shop floor

[MikeH]

I'm moving and my new shop for the time being will be a 12'x16' building. This building has only been supported on the outer rim joists with no support in the center at all. The floor joists run across the 12' section and the only one that has support besides the corners is the center joist. The floor has a ridge in the center splitting the building into 2 sections and the floor dips on both side of the center.

I have to be able to keep some things inside the building and I'm looking for the easiest and safest way to level this floor out.

Help please.... :help:

P.S. I'm also replacing all the siding on the building with plywood first then siding of some sort. Suggestions on siding?

Below are pics... I have more and can take more if needed. Let me know.

The front...

The back center joist (pic above and below) where the ridge is in the floor. What's the best way to straighten this mess out with the twisted board?

Looking under the shed...

 

[scsmith42]

Re: Leveling hop floor

Mike, this is easy.

First, determine where you want to add support columns underneath (such as every 6' along the middle seam). Typically you would use a cinder blocks, set on a flat, solid concrete block on the bottom (such as a 18" square cement paver). Be sure that the ground underneath the paver is flat and level, and then stack cinder blocks on top of the paver until you are within a couple of inches of the existing floor.

Next, at each column measure the distance between the top cinder block and the botton of the floor joists. They do not have to be the same, you just need to know what each distance is.

Now, mark the column locations on the floor inside the building, and set up either a laser or a builders level / transit). Determine your grade reference by checking the perimeter of the building, and then measure the amount of drop in the floor at each column location.

Add the amount of drop to the distance that you previously measured from the top of the column to the bottom of the floor joist. Make a spacer (or combination thereof) that adds up to this distance. Most folks use some type of stack of presure treated lumber such as 2 x 10's, and then plane down one board to get the exact amount.

Now, go back underneat the building and place the appropriate spacers next to the columns. Use a bottle jack and a spacer block to jack up the floor joists next to the column, insert the spacers on top of the column, and let the floor back down. Repeat at each columnn

It is a good idea to add columns below the locations of any of your heavier pieces of equipment too.

 

[MikeH]

Scott,
Thanks for the input. I'm concerned that joists have warped over time. What should I do if they are?

 

[Joe Scharle]

From the pics, I don't think you can physically get under the floor joist. You'd probably be better off if you work from above. I'd saw out an access hole about 2 X 2, that I'd nail back in place before opening the next.

But from the looks of the nails pulling out of the joists, I'm thinking that the only thing preventing the back of that building from collapsing is the flooring! I'd dry stack piers all along there and then replace the band.

 

[scsmith42]

Ditto Joe's comments.

Re fixing your exterior band, if the wood is still solid I would place a 2 x 12 across a couple of the floor joists right inside of the band, jack it up at that point, and then reattach the band to the joists with lag bolts, etc. Then I would move the cinder blocks inward somewhat so that when you let the building back down both the exterior band and floor joist is on top of the block.

RE the curved joists, if you support them in the middle they should straighten out over time.

 

[Bigdog72]

I would replace the warped rim joist. Use engineered rim joist material. Won't warp. Don't bother lagging anything into the end grain on those floor joists. Lags won't hold. If you use hangers for the joists and nail them properly you will be alright. I would put as much support under the joists as possible if you plan on putting machines in there. How long will you be using the temporary quarters?

 

[yanmarman2007]

It looks to me, with a little shovel work you could dig out the front. slide 2 or 3 pressure treated 4x6's under it (of course running opposite direction of floor Joist)
* laser or water level
* level out for a dirt pier.
* Place 8" concrete blocks at each side of 4x6
* jack up a little at a time until you reach a level plane

You really need to get the rim joist above ground anyway.
when you are satisfied that its level. support and level 4x6's in center.

 

[dave "dhi"]

Put a 6x6 along the middle on bottom the opposite direction that the floor joist are running. Then jack both ends up so it has outer band resting on it. That should level all joist then just support each end and middle and toe nail each joist to 6x6 if possible! :icon_thum

 

[KenOfCary]

Regarding the siding:

T-1-11 is cheap and once painted doesn't look too bad. If you want to get fancy and more pricey, then rough-sawn tongue and groove cedar looks real nice.

 

[MikeH]

I would replace the warped rim joist. Use engineered rim joist material. Won't warp. Don't bother lagging anything into the end grain on those floor joists. Lags won't hold. If you use hangers for the joists and nail them properly you will be alright. I would put as much support under the joists as possible if you plan on putting machines in there. How long will you be using the temporary quarters?

Geoff,
Where do you get the engineered rim joists and what is the cost? :dontknow:

 

[Charles Lent]

Having done this 2 times in my life I would prefer putting up a new building to doing it again. This will involve heavy timber, jacking, digging, and a lot of time. The suggestions given to you by yanmarman2007, dave "dhi", scsmith42, and the others are the way to go. You will need at least one 5 ton hydraulic jack(several is better) if the building is empty and bigger if it isn't. Dig troughs under the building to crawl in and then dig out where you want to put the new support columns. Make up some heavy beams or buy steel beams to slide under the building and then jack them up against the bottom of the building at a right angle to the existing floor joists. Lift one end of the building at a time, and only about one inch at a time. Put temporary blocking under the beams to hold that end while you jack the beams at the other end of the building. Don't depend on the jacks to hold the building weight more than a few minutes at a time (safety reasons) and don't go under the building if the jacks are supporting it. Use levels (laser is easiest) to get the building level, then place permanent supports under the beams and re-check for level. Now you can replace the rim joists, but use blocking in between the floor joists to prevent them from twisting when the rim joist is removed. Joist clips will hold better than lag bolts or just nails.

Charley

 

[richlife]

I haven't seen an outcome for this project yet, so I'll add two cents and a warning. Two cents: I agree with the comment that this will cost a lot and is very time consuming.

Depending on the conditions (and it doesn't look like you have a lot of room under there) it can also be potentially very dangerous. I have my shop in a similar building, but the piers are three feet inside the outside edges and the heavy tools had caused the outside edges to sag slightly after about 6 - 7 years. Before expanding the building, I wanted to level the floor by jacking up one end with a house jack and the low edges with an 8 ton bottle jack and placing additional piers. Difficult and time consuming, though successful.

But my big scare happened when the bottle jack, apparently not being quite vertical, slipped and dropped the shed above me about 1/2" back onto the existing piers. Fortunately, I was already super-paranoid about crawling into that small space (about 18" high) and was keeping my body and head well below the bottom of the joists and the pier tops. If my head or back had been up, the force of that instant drop could have sheered my neck or spine.

My message, if you can stay out from below the shed, do so. Make absolutely certain that your new piers are strong enough us sustain a problem and that any body parts are no where near any possible drop area.

Like any woodworking task and the tools used, you need to plan and understand the "what if" and the "next possible actions". And remember that all the best planning and thinking may not be able to account for what actually happens. Protect yourself to the maximum extreme.

Looking back, I'm now sure how I had the courage and/or fool-hardiness to stay under that shed and reset the the jack to get the new pier in place. Was it really worth it?

Rich