Need Help Fixing a Leaning Shed

[MnM]

I am finally ready to tackle a job that has been on my to-do list for several years and grateful to have found this site to get some ideas.

The project is an 8 x 12 playhouse (now a garden shed) that I build for my kids about 20 years ago. Over the years the shed has settled and is now leaning towards the back by about 3-4". I believe the front of the shed has also settled somewhat.

The shed is supported by six 4x4 treated posts (3 in front, 3 in back) set in concrete to a depth of about 42", which is the frost line in the Chicago area. The shed is in the back of the property which has a decent slope from front to rear, meaning that rainwater drains down towards the shed.

I thought about different ways to support the shed after I jack it up but would love to hear some ideas from the forum. I cannot really dig new foundation holes without moving the shed out of the way, so I am looking for alternate ideas on a simple foundation.

Any thoughts greatly appreciated.

 

[K'ledgeBldr]

After 20yrs I'd assume that the majority of the "settling" is done. So, I would just jack and shim every footing until it's level.

Just use PT material for the shimming.

 

[MnM]

That should be a very easy solution.

Any thoughts on whether the 4x4 treated posts would be rotting below grade, therefore, causing issues later?

Also, how would you suggest I anchor the shim to both the house and the post?

Thanks for the idea.

 

[K'ledgeBldr]

Anything is possible.

Shim and level, then monitor. If it continues to move out of level there’s a possibility the post could be rotting. Posts that are embedded in concrete tend to last a bit longer than those that aren’t. The better solution is anchoring the framing member “to” concrete- not “in” it.

 

[MnM]

Yes, I agree. I learned a few things since building the shed and regretted not putting in proper concrete pillars. Fixing later would have required a significant effort.

I am curious, though, if placing a treated 6x6 or larger under the length front and rear would be a viable solution?

 

[K'ledgeBldr]

Then you’re at the mercy of ground heave- it’ll never be “level”.

 

[nadogail]

Shims made of Trex or equal should be unaffected by moisture IMHO.

 

[MnM]

Thanks nadogail. That Trex material is pretty dense, so i don't think it would compress.

My process would be to place a couple of trolley jacks under the rear double joists and then cut the 3 posts using a sawzall. Then, jack the rear of the shed to the height required to bring it to level, plus about 3-4 inches to give more clearance from the ground. Insert shims in the rear and lower the jacks.

This would bring the rear above the height of the front, so I would then need to repeat this process for the front posts to bring it to level.

I assume I'd need to somehow fasten the shims to both the shed and post below it. Any suggestions on how to do this? I was thinking a metal plate that could be screwed to top and bottom of the post, sandwiching the shim in between.

Any thoughts on this? Thanks.

 

[nadogail]

If I am not mistaken you can put screws in the pilot holes you will be drilling in the Trex.
I have not tried this myself, but IMHO it should work.

Try using some of those samples I have seen at the Lumber Yard.

 

[Innovate1]

I have a similar size shed that I bought 15 years ago that was brought to the site already built and has treated beams underneath that usually just sit on the ground. Think they are 4 x 6. After it was in place I jacked it up and set the beams on concrete paver blocks to keep them off the ground and make things last a little longer. Since you want to raise it you could put similar beams and blocks under yours. If you are worried about it shifting you could also anchor it to the existing posts but they wouldn't be holding it up. Yes, it will move a bit from frost heave but I have never found that to be an issue.

 

[captain14]

We have had a couple of garage repairs completed here you may want to check out just to read.

https://www.garagejournal.com/forum/showthread.php?t=254986

https://www.garagejournal.com/forum/showthread.php?t=107111

 

[K'ledgeBldr]

I assume I'd need to somehow fasten the shims to both the shed and post below it. Any suggestions on how to do this? I was thinking a metal plate that could be screwed to top and bottom of the post, sandwiching the shim in between.

I’m pretty sure the weight of the structure will be enough- especially if it’s level.

 

[MnM]

Thanks for all of the tips and the links to other forum postings. Now I have a couple of ideas to think through and I am sure both would work. Need to decide which would be easiest to implement.