Lifting a shed

[srmofo]

Looking for opinions from the collective hivemind.
Long story, short. Built a 10x12 shed a few years, then some changes were made to a nearby creek by the city and now my back yard floods significantly in a flash flood type event. In the past 7 years, I have had 4 floods with last year being the worse and getting about 19" water inside my shed which is already about 10" above grade minimum. I was here for 3 years before I built the shed and only had a wet yard for the most part. Luckily I did prepare for that during construction and used premium materials so it hasn't destroyed it, but its a real PITA to get everything all dried out. Its a flash flood type scenario where the water comes in within about 30-45 minutes and is gone again in 2-3 hours. City already told me to pound sand essentially, not looking to start a legal battle for what can be solved for a few hundred dollars.

I'd like to raise it between 19 and 24". Even if that's not enough for all floods, if it stops a majority of them its still a win and its much easier to take care of 1-2" water than 19".

What I'd like to brainstorm is how would you build the structure for the lift? The water table is very close to the surface so posts directly in the ground would rot quickly, so definitely concrete piers below the frost line. The shed is trapped in a corner of the yard so moving it to dig new posts is not really a viable option without taking down 1 or 2 trees. I have plenty of bottle jacks and support cribbing to do the actual lift, and if that fails there's some Amish folks in the area that do the lift for me. Moving the shed to another corner could be an option but I'd still have to raise it 9-10", it would just be easier to dig...but I really like the shed where its at.

Would you then use 6x6 support columns from piers up to a beam that supports the shed joists?

Would you extend sonotubes above grade and directly support the beams on the concrete piers and brackets?

How many lift columns? 4 or 6?

What support bracket for pier to posts/beams would you use?

I think I like the first option, but I am concerned that when driving a mower up the ramp into the shed would experience enough force that the posts would tip and the shed come crashing down front to back. Diagonal bracing could help with that , but would it be enough? Decks don't usually have that problem because they are anchored to the house and its only foot traffic.

Like I said I've got ideas in my head but not sold on any 1 thing yet, just would like to hear some opposing ideas. Here's the foundation layout as it is and what I was thinking for option 1.

 

[larry4406]

There was an awesome post on here several years ago where the member jacked his entire garage up and raised it several feet while also raising the foundation up to solve a flooding problem.

It was an epic build. I will see if I can find it.

 

[Hank11]

If it was me, I would consider moving the shed up the hill, just a little bit to where that small wood pile is now. You could build your new footings or set poles, slide the building up onto it and it’d be over with. Looks like you gained a foot of elevation at least if you move it up there and that would keep it closer to the ground and easier to get in and out of.

 

[nadogail]

Back in the day when I was but a kid, we used to lift Telephone Booths with Car Jacks.

After add Diagonal Bracing on the walls, you might be able to raise each wall a few inches, add cribbing and then move the jacks to another wall.

Eventually you will raise the struckure to your desired height.
this process will not be fast, but with Junkyard Jacks, your expenses will be minimal.

 

[walta]

Make sure to understand your towns shed rules.

In some places they are allowed as temporary building with few regulations. But to be temporary means NO foundation NO concrete no electric no water.

Seems like most shed set on 2 or 3 PT runners in contact with the ground so 6 or 9 columns would put you 16 inches above grade.

Walta

 

[crazylunker]

I have a similar problem also caused by the town management. I get up to 41 inches in a flash flood and thankfully it never reaches the house and it's gone almost as quick as it shows up. long story short I always struggled to move my equipment trailers when there was a threat of possible flooding. About a mile from my house a new cell tower was being built and I noticed alot of tri axle activity. I stopped there and asked what they were doing with the fill they were removing, the guy practically paid me to let him deliver 18 loads of fill to my house because I was right around the corner. I now have a nice elevated spot where the trailers are safe without disturbing the natural in/out flow of flood water.

 

[Skiff Builder]

I have done this many times in the past.
(6) 10" tubes, with 2-3 sticks of rebar ea, right up to the shed beam/joist.
Any number of straps or connectors to choose from wet conc to beam.
Figure (1) 80lb bag conc per foot of tube. Could always add extra stack(s) of blocks if shed floor flex's.
Good racking resistance.
Also think about "pinning" the lower end of your ramp into the ground with steel stakes.

Very nice shed you have!

 

[Wubicon]

Back in the day when I was but a kid, we used to lift Telephone Booths with Car Jacks.

After add Diagonal Bracing on the walls, you might be able to raise each wall a few inches, add cribbing and then move the jacks to another wall.

Eventually you will raise the struckure to your desired height.
this process will not be fast, but with Junkyard Jacks, your expenses will be minimal.

I'm following this thread because I need to figure out how to raise up a plastic Costco garden shed and replace the foundation it's sitting on and I think this post is the essence of what I need to do to get the shed up, and do something with the existing base and put something new down.

 

[Innovate1]

Some posts with diagonal bracing should take care of concerns about side force when driving the mower in or out. What's the floor framing like - that determines where posts need to be and how many. You could do some concrete base blocks and then treated posts on top of that. The house I grew up in was like that with the concrete base blocks about 15 x 15 x 18 inches. Think they got them cheap from somewhere that made them from excess concrete from jobs. But you can get smaller ones at big box stores. You're going to need a much longer ramp to raise it that much. I have a shed on skids. After it was dropped off I raised it just enough to put some pavers under the skids thinking it would keep it all off the ground. But then a ground hog moved in and pushed a bunch of dirt all around - wondering if I should have raised it more to keep the critters out. Or maybe I should have done some sort of skirt. Wouldn't keep them all out but might discourage the big ones.

 

[captain14]

This is how one GJ member raised his garage. There’s been a couple of others that posted their process in a thread.

 

[Firebrick43]

I would do a compacted crushed stone pad a few feet larger than the pad. Every raised shed with space under it eventually becomes a home for ground hogs and skunks in my experience

 

[srmofo]

I would do a compacted crushed stone pad a few feet larger than the pad. Every raised shed with space under it eventually becomes a home for ground hogs and skunks in my experience

Fortunately, I already have about 4" #57 under it and with the high water table and generally damp conditions critters haven't been much of a problem. Of course is caked in with lots of mud from the flooding , but its there.

Seriously the water table is so high, I have burrowing crayfish in my yard that like to leave little mounds of soil. Thee little guys

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[srmofo]

Some posts with diagonal bracing should take care of concerns about side force when driving the mower in or out. What's the floor framing like - that determines where posts need to be and how many. You could do some concrete base blocks and then treated posts on top of that. The house I grew up in was like that with the concrete base blocks about 15 x 15 x 18 inches. Think they got them cheap from somewhere that made them from excess concrete from jobs. But you can get smaller ones at big box stores. You're going to need a much longer ramp to raise it that much. I have a shed on skids. After it was dropped off I raised it just enough to put some pavers under the skids thinking it would keep it all off the ground. But then a ground hog moved in and pushed a bunch of dirt all around - wondering if I should have raised it more to keep the critters out. Or maybe I should have done some sort of skirt. Wouldn't keep them all out but might discourage the big ones.

Current and current proposed structure. 12' wide x 10' deep.

Would definitely have diagonal bracing on both sides and likely add it to front and back as well. Since its only a shed and a majority of the load is carried at the sides, adding above grade supports to stop any bounce seems like a reasonable approach .

Only remaining decision is whether to add 2 additional columns and beam in the center span.

My experience with ground rodents is the more open and unprotected it is, the less inviting it is for them. both from predators and the weather.

 

[srmofo]

Make sure to understand your towns shed rules.

In some places they are allowed as temporary building with few regulations. But to be temporary means NO foundation NO concrete no electric no water.

Seems like most shed set on 2 or 3 PT runners in contact with the ground so 6 or 9 columns would put you 16 inches above grade.

Walta

Pretty fortunate in my area. City doesn't even require a permit for anything less than 200sqft.

Good call on the blocks. I hadn't even thought about using them instead of poured. Could probably even cap them with solid half blocks to get an extra 4" lift and keep the weather out.

 

[srmofo]

Back in the day when I was but a kid, we used to lift Telephone Booths with Car Jacks.

After add Diagonal Bracing on the walls, you might be able to raise each wall a few inches, add cribbing and then move the jacks to another wall.

Eventually you will raise the struckure to your desired height.
this process will not be fast, but with Junkyard Jacks, your expenses will be minimal.

I've actually got several bottle jacks and floor jacks I planned to use to actually lift along with plenty of 4x4 cribbing left over from the fence in the background. Bought the 8' posts instead of 6' because I knew I would need to do this eventually.

 

[nadogail]

I've actually got several bottle jacks and floor jacks I planned to use to actually lift along with plenty of 4x4 cribbing left over from the fence in the background. Bought the 8' posts instead of 6' because I knew I would need to do this eventually.

Being Kids in the late 1940’s we used bumper jacks.
That was back when cars had real bumpers.

 

[cody1325]

I helped a buddy get a shed placed in his yard. His uncle had loaded it onto a trailer using a hydraulic Simplex "railroad jack" which later got drafted to position and level the shed. If I were doing this with my stuff, I'd probably grab my mechanical ones and the Hi-Lift.

 

[Just_Steve]

Call one these guys they'll lift you right up.

 

[captain14]

Call one these guys they'll lift you right up.

That would be my first thought. When you watch them place and remove (repo) sheds on YouTube, they can make it look easy and safely.

 

[75gmck25]

When they delivered a shed in my neighborhood they use a Moffett-like vehicle on one end, and wheel assemblies bolted on the other end.

Using only one guy, he pulled the shed off the flatbed and attached the wheel assemblies. Then the moffett slide in under the other end and pivoted so it was pointing right at the end of the shed. Then he just drove the shed into the yard like it was a big wheelbarrow. This is similar to how he moved the shed.