Adding a sill plate to a pole building

[Big-Al]

Has anyone ever done this?

My issue is I have a pole building that is probably 40-50 years old. About 15 years ago I poured a slab. Ever since the building rises up a tad every winter and does not settle back down. I now have a gap of as much as 6 or 8 inches between the slab and the start of the metal wall. Would it be feasible to install a sill plate and cut off the poles and anchor the plate to the slab? Any other ideas out there to solve the issue?

[LightningBG]

The short answer would be "NO", you cannot do that.

Problem would be that you wouldn't have anything going down below the frost line.

I'm not really sure why the building is heaving, since those poles should be down below the frost line.

Only thing I can think of is to jack the whole building up, cut off the poles and dig them out of the ground and pour footings, but even that is questionable. Pole buildings get a lot of their strength and rigidity from those poles going down into the ground. and if you cut them off it would just be the equivalent of a weakly built stick frame construction.

[CAMAN]

My first thought is drainage. Is there proper slope leading away from the building on all sides?

[Big-Al]

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Problem would be that you wouldn't have anything going down below the frost line.

I thought about that but even if the poles are below frost line they are not protecting it from the frost now. The slab is not moving at all. The edges of the slab are extremely thick, probably close to 14 inches. If the slab is not moving at all right now, why would it be an issue with the poles tied to a sill plate and the sill plate anchored to the slab? I am open to any and all advice and suggestions because I certainly have no experience in this type of work. I would be hiring the job out.

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Only thing I can think of is to jack the whole building up, cut off the poles and dig them out of the ground and pour footings

That is certainly a possibility.

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Pole buildings get a lot of their strength and rigidity from those poles going down into the ground. and if you cut them off it would just be the equivalent of a weakly built stick frame construction

Now that I had not that about at all. I suppose that might make the whole thing impossible.

[Big-Al]

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Is there proper slope

There was generous amount of sand hauled in when the building was constructed. Having said that, I am sure (or at least I would hope) that the poles go well into the clay hard pan that is 1 to 2 feet below the surface in this area.

[LightningBG]

I'm still stumped as to why it's moving...

Was there any movement before the slab was poured? or even if there was, would you have noticed it without a solid reference point?

[nonteepical]

is there a possibility of a high water table where the building is located? i've seen poles heave, if they had concrete poured around them at the bottom of the hole when first installed they don't like to settle back down to original after the ground thaws, they keep creeping up year after year. just a thought.

[Big-Al]

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I'm still stumped as to why it's moving.

And I am too. There was no movement that I was aware of before the slab was poured. As you say I did not have a real reference point so there may well have been some but certainly not as much as there is right now. I wanted to tie the poles the the slab when it was poured but I was advised against it because "the slab was going to move". Well the slab is very stationary and the whole building is moving. It is 32x32 and it initially was variable in the movement but now the entire building has heaved 6-8 inches in 15 years.

[Surface Tension]

Even the though the posts are below the frost line they can heave, Frost can grab the post from side and lift the post up.

Good chance the post has some rot to it giving it a collar and the soil around it a good hold when it heaves. A post set into a bracket on top a pier will not allow that to happen.

Slab slab could be heaving and settling. If the slab is not floating past the post it'll lift it. Once lifted it won't settle like the slab will. Each year it can inch the post up further.

Down South you don't need to posts below the frost line and they are often shallow or set on a pad with bracket.

Once the sheeting is on that wall is stiff so I wouldn't worry about that, you can allows ad additional dia bracing.

I'd have to ask that are you positive the posts are heaving and its not the slab sinking?

If the posts are heaving then you'd have some racked and buckled walls.

Having 14" integral footing around the perimeter, your sort of in luck if you choose to use a sill plate and cut the posts off.

I think your OK there but you might want to check to see if that is enough to set a post on.

Be sure to remove the post below grade when your finished.

Cutting off each post and placing in a frost pier(new footing) is another option.

Either way you'll have to take the weight off the posts and lower the building back down.

Since your hiring this out I'd like to hear what the contractor has come up with.

[Big-Al]

I really do think that it is the posts heaving and not the slab sinking. I would think that I would have more than the one hairline crack in the slab if it was doing a lot of moving. I certainly would think it would not move so perfectly that I wouldn't see more cracks than I do.

As far as the walls buckling, I have really been expecting to see that. There has been issues with the man door operating properly at times. Originally portions were up more than others but now it is a fairly consistent distance up all the way around.

[LightningBG]

Try and find a really old farmer. I'm talking REALLY old. 85 plus. they always have solutions for stuff like this. but it might take a while to get the answer... And make sure you have coffee on hand. Cheap coffee.

[Surface Tension]

The simplest fix would be adding a skirt board, clad it if you want.

That isn't solving anything but if the building isn't racked it''ll get you by.

[walleyeseeker]

At the rate you are saying this building is coming up, the problems are going to start growing exponentially. Your best solution would be to dig around one of the poles and see if it is sitting on a concrete pad. Also, you can see how deep they are buried. If you find it is actually lifting, then you would be best finding a good pole shed builder to advise or help you get it under control. If you cut the poles off, your building will fail in a big wind. It is not designed to stand that way. Good luck and be safe.

[jeffreyd]

I have to say that i am so impressed with the people on the board. This question that i just read has a ton of questions and problems. the amount of information that was provided back in feedback is truly amazing considering most if none of you have seen this issue. I am so honored to be associated to such a fine group of people. Jeff

[Big-Al]

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The simplest fix would be adding a skirt board, clad it if you want.

I have certainly thought about doing something like that. A permanent fix would be preferable but I have a hunch it is going to cost a whole bunch.

[Big-Al]

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Your best solution would be to dig around one of the poles and see if it is sitting on a concrete pad.

I think I will do that, but mostly to see how deep they are. I highly doubt that they are sitting on concrete. I would sure think they are just poles with no footings of any type.

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finding a good pole shed builder to advise

I think that will be my next step.

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If you cut the poles off, your building will fail in a big wind.

I just made an assumption that anchoring the poles to a sill plate and anchoring the plate to the slab would work but I guess that may not be the case.

I sure do appreciate all the advice and suggestions.

[Surface Tension]

You'll have to be sure if the posts are heaving or the slab settled. Digging around one post as walleyeseeker described and looking for separation between the post and pad will tell you that. Because of the age of the building don't be surprised if you find a rock instead of pad,

As I mentioned about the slab catching the posts and lifting them up. Is there a barrier(1+" foam) between the slab, posts and skirt board.

Poles are set into the ground because it is a fast way to raise a building while adding a frost footing.

The option to leave the floor gravel or a floating slab at a later date is always there.

You can most definitely build a pole building on a slab. Difference is you'd add the bracing but that fast and easy part slips away because instead of your posts being in ground you'll have to brace them in place as you build. That would be true if you set the posts on top piers w/brackets.

Wind isn't an issue here, what is is the integral footing of the slab in place. Is it thick enough and wide enough to support the weight being put on it in each location of the posts. Even though it'll be set on a sill plate that plate can't distribute the weight.

We know its 14" thick but we don't know about rebar or how wide that integral footing is.

[Big-Al]

I did a bit of research today. I talked to a local fella who lived in this place when the pole building was built. I had guessed on the age, but was very close, it is just shy of 40 years old. He did say the there is a concrete pad under the poles and he thought the poles were 5 feet in the ground.

The slab was poured about 14 years ago. The 1/2" rebar pattern was 8" x 8". The edge 14-16" and is 18-24 " wide and tapers from there to about 6" I had several people tell me that it was way overkill but that is what I wanted. I did not want it to start breaking up in a few years.

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Is it thick enough and wide enough to support the weight being put on it in each location of the posts.

I am confused on this statement because once the poles were cut they would be setting on the plate. There would be a void under that spot because the poles would be gone. I envisioned a steel bracket of some type that the poles would sit in and that would be tied to plate and for that matter through the plate and right into the slab.

Thanks Frank and all the others for you thoughts and suggestions. Hopefully this will become reality down the road. I'm tired of a garage that gets snow drifts in the winter.

[Surface Tension]

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Is it thick enough and wide enough to support the weight being put on it in each location of the posts.

"It" being the integral footing around the perimeter of the slab..

Instead of the weight of the building being dispersed over studs on 16'-24" centers like you would a stick framed wall.

you have that weight on 8' or 10' centers.

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The 1/2" rebar pattern was 8" x 8". The edge 14-16" and is 18-24 " wide

Overkill for a floating slab inside a pole barn but now your setting weight on it.

Having that I think your OK putting weight on the slab with those 8' to 10' centers.

Using the brackets and sill plate anchored as you described is good and what you would do.

Besides cutting each post at your desired height minus the sill plate, you'll still need to create a void at each location a post enters the slab and remove a section of each post to 1' below the slab or else it'll continue to push up the sill plate with frost.

Since your sill will be spanning that void your post will act like a stamp. For that reason I'd 3" thick for the sill with two treated 2x6s.

[jentz]

The simplest fix would be adding a skirt board, clad it if you want.

That isn't solving anything but if the building isn't racked it''ll get you by.

Best idea here/With one suggestion,when installing do it like window jambs in log buildings,Nail it on, but where the nails go through the material predrill elongated holes then nail,so whem the slab or the building moves up and down the skirt slide up and down because of the elongated nail holes,Dont completly set the nails so movement is possible.

[jentz]

If you want to cut the poles and plate under them, there is some hardware to serve your purpose, Its called hold downs. I believe either silver or simpson strongtie makes them their number (of the holddown is HD then a number) as HD2 Is a 2 inch hold down two inches tall thats a example you'd need HD10?? HD12 they bolt in the concrete at their bottom for you a drilled hole with a leadhead set or expansion bolt,Then there are two holes for through bolts in the posts,They were designed for earthquake stress but now have many other uses

[mabr]

Here’s what I would do for what it’s worth. Actually did it for a sinking pole barn instead of a lifting one and it cured all the issues these folks had. It is a lot of digging though.

Dig out around posts. Temporarily jack up building to support. Cut post where the post is still solid, I’m guessing you’ll have rotten posts. Dig your footing down below frost line depending on where you’re at. Put a solid concrete (cookie) block at the bottom, cut temporary post (hopefully you have an old 6x6 around) let weight of building back down on pad to compact the dirt. Jack up again close to where it needs to be, cut a new PT post to fit from remaining post to pad. Sandwich around this new post with PT 2-2x6x6' or 8' and a ripped to flush 2-2x10x 6 or 8 (assuming 6x6 posts)on 3 sides (save the remaining 2x8 for after it’s in the hole) nailing them to the new post and into each other. The 2x6 & 8 should overlap the joint by at least 3 ft on each side. VISUALIZE a post wrapped all the way around with the wrap extending equally from where the post was cut off by at least 3 ft. Then set weight back down on it again, you may have to shim the bottom to get it just right but you’ll be close. Then pour 2 ft of concrete around the new post, then put a 12" sauna (sp) tube around the whole thing (you’ll have to split it)setting on the area just poured. Back fill to grade and Pour until concrete is a couple inches above grade.

Only thing I didn’t mention is something you might want to do but if footings are deep enough I personally wouldn’t worry, drill some holes at the bottom of your new post and push some rebar (double post width in length) through to prevent lift.

Hope this all made sense.