Getting into my head too far. How to support my storage shed?

[Sanderguy777]

(On mobile. Sorry for the formatting, but I want things separated so they're easy to find).

I'm building my parents a couple of 96sq ft storage sheds (the city wants permits for anything more than 100sq ft). One will store a garden tractor (riding mower with a better engine and thicker steel) that weighs 550lbs, and miscellaneous other lawn care stuff. I doubt it ever sees more than 2000lbs total including people grabbing stuff). The other will be for mainly Christmas decor and maybe some old books. Nothing too heavy and probably everything on shelves along the walls.


I built myself a shed a couple years ago. It's 8x12, has 6 posts set in concrete, and used 2x6 floor joists, 3/4" GCPT (ground contact pressure treated) ply flooring, and PT studds and rafters. The only non PT wood on it is the siding and roof sheathing (7/16 OSB and 5/8 ply or OSB respectively). I made some mistakes I want to rectify:
1. Used no construction adhesive on the floor and only 2x6 joists. This means the floor squeaks and moves a bit too much. I want to solve that issue.
2. I put posts in concrete footings that means I can't really fix anything when they inevitably rot (they're just ground contact rated pressure treated, so that will probably not be even 20 years. I'd like these to EITHER last a long time, or at least be a relatively simple fix (yes I have done some jacking up buildings work).



My question with this build is: how do I support the thing? I am trying to figure out if I really need NINE 24" deep 16" piers with a CCA post set in it (that would be 21 bags and $105 of concrete and $46 per 4x6x144" post). Or can I get away with a gravel " pad" and just building on some 4x4s I replace as needed.

We live in SW Missouri, so clay soil, lots of rain and humidity and bugs. They also have a VERY rotten tree and root system under where the sheds are going (the tree has 3 trunks, NO canopy left at all. Not even a twig, and a 6ft section of the trunk just gave up and fell off last week!) WE obviously have tornadoes, but I just want this not to fly away like Dorothy's house in a strong 80mph wind.

I assume I need piers, and wanted to go with an 8" pier in a form, a bracket on top, and then directly bolt the rim joists to the bracket (or probably add a 4x4 post that's just long enough to bolt the bracket to and the joist above it). 9 piers for the mower shed and 6 for the Christmas shed. I was also planning on just 2x8 joists with no sistering and just under 8ft spans)

The alternative option would be the same thing, but using 2x6s, and having 3 CCA rated 4x6s (smallest possible size) on end going between the 6 or 9 piers perpendicular to the joists, just like a deck is built.

The issue is that I am looking at concrete prices and needing 3 bags for an 8" pier and 22 for a 16"! Add to that the 4x6s are $46 per, and then needing spacers to keep them off the pier surface. If I do the normal brackets, they're $15 per and that's $270 if I just did 9 piers per shed like I'm leaning towards.

Is this overkill? Am I overthinking this or am I just realizing what it costs to build a building in 2026?

 

[Hank11]

Your last two sentences are the answer.

I think I’d put a post in each corner and then in the middle of the 12 foot span, I’d pour a little pier or a little footing for a pier to support the middle. Hardest part is gonna be putting the holes in the ground with a lot of roots and rocks to bust through, but it’s only four holes. Dig the holes on the large size so you can put the posts in, put the rim joists on and wiggle things around until you get the bottom square. Be sure tp check level. Put on a brace to hold it square, pour the concrete. All downhill from there.

 

[Skiff Builder]

As someone who scratch built thousands of custom sheds for a living in my mid 20's:

On the grass ,build an 8'x12' perimeter frame from 4x4's. We used 40d nails to fasten. Use 4" solid conc block on the corners and get frame level. Add 4x4 floor joists on 24" centers. Place more blocks under the floor frame. I would have that done by 9:00 am. Deck it with 3 sheets of 3/4 t&g Plywood or 5/4 x6 treated decking. Build on from there.
Never a call back or failure in 20 years.

 

[Sanderguy777]

Your last two sentences are the answer.

I think I’d put a post in each corner and then in the middle of the 12 foot span, I’d pour a little pier or a little footing for a pier to support the middle. Hardest part is gonna be putting the holes in the ground with a lot of roots and rocks to bust through, but it’s only four holes. Dig the holes on the large size so you can put the posts in, put the rim joists on and wiggle things around until you get the bottom square. Be sure tp check level. Put on a brace to hold it square, pour the concrete. All downhill from there.

So you'd just put the posts directly in the concrete?

That's what I did on mine. But I'm worried they'll rot being the junk "healthy" stuff they use now (anyone dying from gnawing on timbers probably isn't getting poisoned by arsenic LOL)

 

[Sanderguy777]

As someone who scratch built thousands of custom sheds for a living in my mid 20's:

On the grass ,build an 8'x12' perimeter frame from 4x4's. We used 40d nails to fasten. Use 4" solid conc block on the corners and get frame level. Add 4x4 floor joists on 24" centers. Place more blocks under the floor frame. I would have that done by 9:00 am. Deck it with 3 sheets of 3/4 t&g Plywood or 5/4 x6 treated decking. Build on from there.
Never a call back or failure in 20 years.

So just set it down on the ground? How strong are the winds where you are? We have had 80 and 90mph gusts here last year.

I think you're right, I'm just curious if you've seen this work in real wind. Last thing I want is to be like the Californians who's trampolines roller down the freeway the first day of Idaho winds


I want 8x12, so would I just make the frame that size? I'm just making sure that there isn't a reason to only build 8x8. Also, are the joists sitting on top of the frame, or inside it? Is there a "span" they have to hold, or are they just sitting flat on the ground?

 

[nadogail]

I am fond of Copper Napthate for termite control.
I buy it at Home Depot, every thing I have painted it on has been termite free, I then cover it up with Kilz.

 

[Sanderguy777]

I am fond of Copper Napthate for termite control.

Is that what they use in ground contact pressure treated posts? Or is that something to add to them?

And does it keep them from rotting in general, or just from getting gnawed at?

 

[nadogail]

I don’t really know, I am aware that copper repels those things that gnaw on it.
That is why boats are painted with Copper Bottom Paint.

 

[Dig Doug]

Tuff shed uses a 6 inch metal stud floor framing - you can get different metal gauge

As for up lift
Instead of sinking a post - I’d probably go with some sort of hold down in each corner
strap, all thread etc

Tuff Shed

Tuff Shed is America's leading provider of installed storage buildings and garages.

www.tuffshed.com

tuff shed floor / base



Simpson strong tie for up lift

https://www.strongtie.com/straptieholdowns_holdownsandtensionties/sthd_holdown/p/sthd

 

[Skiff Builder]

The entire frame was built flush and sat on 4" masonry blocks set at the corners , halfway between the corners and under the center of each cross member of the frame. It would be at least 3.5" above ground (and more ground was not level). We would use this system up to 12" wide x any length shed.

Exact size of frame depends on wall sheathing thickness. Most times I would make exact 96" x 144" overall frame dim.

My current shed sees 70 mph on the coast. One could use auger style ground anchors as Tie downs- that's what I do when blocking up boats for the Winter.

 

[cgrutt]

If you have the room I'd run three 4x4 (or 4x6) posts across top of your piers like a beam and run the joists across the three beams as you would a deck. This will distribute Load and support each floor joist. Run 12 OC if you really want to beef it up. I wouldn't encase posts in concrete use a metal connector on top of pier and short section of post to level if needed, or attach directly to the beam. Should be able to use 6 piers this way. Only disadvantage is floor will be a bit higher off ground.

 

[Sanderguy777]

I don’t really know, I am aware that copper repels those things that gnaw on it.
That is why boats are painted with Copper Bottom Paint.

Ah, makes sense.

 

[Stuart in MN]

I would set sleepers on a gravel bed, no concrete footers. If getting blown away in the wind is a real concern, use a few of those screw anchors chained to the corner.

Also, make sure that code thing about structures under 100 square feet allows for multiple structures - otherwise, theoretically a person could fill up their yard with dozens of sheds, so their city may have addressed that in their regulations.

 

[Sanderguy777]

Tuff shed uses a 6 inch metal stud floor framing - you can get different metal gauge

As for up lift
Instead of sinking a post - I’d probably go with some sort of hold down in each corner
strap, all thread etc

Tuff Shed

Tuff Shed is America's leading provider of installed storage buildings and garages.

www.tuffshed.com

tuff shed floor / base



Simpson strong tie for up lift

https://www.strongtie.com/straptieholdowns_holdownsandtensionties/sthd_holdown/p/sthd

Great idea for uplift!

Much better than a post base, assuming those don't cost $15 or more.

 

[mikedodge]

My sheds are for garden tractors. Both of them the floor is a 2x6 perimeter with 2x6 joists sitting on a stone at each corner. One of them has a 4x4 or it might be 2 2x4s stuck together underneath the floor joists perpendicular to them in the center. On that one the joists run front to back and across the front and back there is a 2x4 on its side under the floor framing to give the ends of the joists more support.

 

[Dig Doug]

Great idea for uplift!

Much better than a post base, assuming those don't cost $15 or more.

Look at all thread
or
Home Depot for a 36 inch long strap run a bolt thru it w/ a nut - tighten it up so it will bite into the concrete post hole

this is a little light duty - maybe double it up stack one on top each other

 

[Sanderguy777]

The entire frame was built flush and sat on 4" masonry blocks set at the corners , halfway between the corners and under the center of each cross member of the frame. It would be at least 3.5" above ground (and more ground was not level). We would use this system up to 12" wide x any length shed.

Exact size of frame depends on wall sheathing thickness. Most times I would make exact 96" x 144" overall frame dim.

My current shed sees 70 mph on the coast. One could use auger style ground anchors as Tie downs- that's what I do when blocking up boats for the Winter.

What do the ground anchors run? I looked once and they seemed expensive. But I am not sure concrete and brackets are affordable anymore.

 

[Sanderguy777]

If you have the room I'd run three 4x4 (or 4x6) posts across top of your piers like a beam and run the joists across the three beams as you would a deck. This will distribute Load and support each floor joist. Run 12 OC if you really want to beef it up. I wouldn't encase posts in concrete use a metal connector on top of pier and short section of post to level if needed, or attach directly to the beam. Should be able to use 6 piers this way. Only disadvantage is floor will be a bit higher off ground.

So run 4x6s on the 8ft dimension, then 12ft 2x6s on top of them? that is the only way I can imagine 6 posts working (running a 4x6 on a 12ft span to support 2x6s on the 8ft direction wouldn't work.)

 

[pima67]

Don't know if they are available anymore but i used 4 rail road ties as the base and built a normal floor with ring and floor joists on top for a 6x12 shed. Lived in earthquake prone country so wanted it to "float" on top of the ground rather than be secured for any ground waves that might move through the area. But luckily the "big one" never came.

 

[Stuart in MN]

What do the ground anchors run? I looked once and they seemed expensive. But I am not sure concrete and brackets are affordable anymore.

Don't forget to include labor - driving in a few anchors sounds like a lot less work than digging and pouring footings.

If you do go with footings, use those galvanized post bases - you set a piece of all thread in the top of the concrete, then fasten the post base to the all thread, and finally fasten your wood to the post brace. No wood is buried in the ground or in concrete to rot.

 

[cgrutt]

So run 4x6s on the 8ft dimension, then 12ft 2x6s on top of them? that is the only way I can imagine 6 posts working (running a 4x6 on a 12ft span to support 2x6s on the 8ft direction wouldn't work.)

Sorry my bad, I was visualizing 12' beams but should probably have a pier supporting in middle. So either use two beams (6' apart with 1' overhang should be good with 2x6 joists) or add three more piers and run a third beam down center.

 

[Skiff Builder]

What do the ground anchors run? I looked once and they seemed expensive. But I am not sure concrete and brackets are affordable anymore.

https://www.tractorsupply.com/tsc/p...fCbGRoObWXo3Clzy3irKiMiTUbFbAiZRoC7sQQAvD_BwE

 

[Hank11]

For the shed that’s gonna take the garden tractor maybe you should just build the shed on leveled out dirt, lay down some heavy plastic and then gravel on top. A baby pole barn. You can just drive the mower in and out. No ramps to build, no complication. And can’t get much cheaper. If you think it through upfront, you could even come back later and pour a concrete floor inside of it.

And you might look around for some pressure treated material that’s made to go in the ground. But yes, if cost was the prime directive, I would just use whatever they have at the big box store.

 

[Sanderguy777]

Don't know if they are available anymore but i used 4 rail road ties as the base and built a normal floor with ring and floor joists on top for a 6x12 shed. Lived in earthquake prone country so wanted it to "float" on top of the ground rather than be secured for any ground waves that might move through the area. But luckily the "big one" never came.

Yeah. that is what I'd like to do, but I'm worried that the wind might do something since I live in tornado alley.

Don't forget to include labor - driving in a few anchors sounds like a lot less work than digging and pouring footings.

If you do go with footings, use those galvanized post bases - you set a piece of all thread in the top of the concrete, then fasten the post base to the all thread, and finally fasten your wood to the post brace. No wood is buried in the ground or in concrete to rot.

No labor. I'm my own labor .

If I do piers, then yeah, the brackets are worth it.

Sorry my bad, I was visualizing 12' beams but should probably have a pier supporting in middle. So either use two beams (6' apart with 1' overhang should be good with 2x6 joists) or add three more piers and run a third beam down center.

Yeah. The overhang idea is good. makes the load distribution for the walls and any snow a bit harder, but it should work fine.

I really like this idea and it might make it possible. Or do you think I should go with more piers that are smaller (like 5 per row that are 8" each instead of fewer bigger ones). Idk what the math works out to, load wise.

https://www.tractorsupply.com/tsc/p...fCbGRoObWXo3Clzy3irKiMiTUbFbAiZRoC7sQQAvD_BwE

How would I drive those? We have TONS of rocks here and that doesn't have a way to drive it mechanically, it doesn't look like it anyway.

For the shed that’s gonna take the garden tractor maybe you should just build the shed on leveled out dirt, lay down some heavy plastic and then gravel on top. A baby pole barn. You can just drive the mower in and out. No ramps to build, no complication. And can’t get much cheaper. If you think it through upfront, you could even come back later and pour a concrete floor inside of it.

And you might look around for some pressure treated material that’s made to go in the ground. But yes, if cost was the prime directive, I would just use whatever they have at the big box store.

You know what? I love that idea. that is all that needs and I could even seal it decently for bugs if we want.

 

[Stuart in MN]

No labor. I'm my own labor .

That's what I meant. If it were me, and using screw anchors cost a little more but would save me a couple day's worth of back breaking work, I know which method I would choose.

 

[Snapped-off]

My shed is sitting on a gravel base that's tamped down.

I intend to anchor it with rebar driven into the ground to satisfy permit requirements.

 

[MushCreek]

My shed is sitting on concrete deck blocks, but the ground doesn't freeze here. I don't have it tied down, but the shed and contents are pretty heavy, and there's not much wind where it's situated. If a tornado hits a shed directly, all bets are off anyway.

 

[Sanderguy777]

My shed is sitting on concrete deck blocks, but the ground doesn't freeze here. I don't have it tied down, but the shed and contents are pretty heavy, and there's not much wind where it's situated. If a tornado hits a shed directly, all bets are off anyway.

Oh, for sure. I just want to give it the best chance for success it the winds are 80 or 90mph like they were once last year.

I saw Hank11's comment and I really like the idea of a pole barn design. 4 piers would be plenty for the mower shed since it just needs to resist being carried off or crushed by snow load. Then the other shed can get 6 piers of we want a floor or 4 and a gravel floor if not.

I could totally do 10 piers. It's when it's nearing 20 that it's gets too much.

 

[CraigStu]

It seems like your big concern is the wind plus the effort and cost for concrete piers. I'd be looking at the screw anchors figuring they would be a lot less work than piers. Then I'd research the best gravel to use to create a flat surface. I might even skip the gravel and look at concrete blocks made for the purpose of setting structures on. The guys on the show about building or rebuilding camp houses in Maine sit a lot of their stuff on what look like concrete discs maybe 6" thick and 15-18" diameter. You could make small gravel pads for them to make it easier to get them all the same height. Also think about standard house construction where floor joists are 2x10s on 16" center that span 14feet. It's a lot easier to up the 2x size than build more piers.

 

[Hank11]

No piers. Poles in holes in ground set in concrete.

 

[Sanderguy777]

No piers. Poles in holes in ground set in concrete.

Will general normal ground contact 4x4s last that way? I did that with my shed, but I ended up needing like 10 bags for one hole.

If you think that will last, how big of a hole and should I go with 4x4s or 4x6s?

 

[MushCreek]

To me the hardest part is the digging. They make concrete forms called 'bigfoot' or something similar. They are bigger at the bottom, thus preventing uplift once buried. I like the idea of keeping all of the wood, even pressure treated above the soil.

https://www.homedepot.com/pep/SQUARE-FOOT-22-in-x-16-1-2-in-x-22-in-Plastic-Concrete-Footing-Form-SF22/202532049?g_store=&source=shoppingads&locale=en-US&fp=ggl&pla&mtc=SHOPPING-BF-CDP-GGL-D22-022_009_CONCRETE-NA-NA-NA-PMAX-NA-NA-NA-NA-NBR-NA-NA-NEW-NA-_PMAXTEST&cm_mmc=SHOPPING-BF-CDP-GGL-D22-022_009_CONCRETE-NA-NA-NA-PMAX-NA-NA-NA-NA-NBR-NA-NA-NEW-NA-_PMAXTEST-20381683398--&gclsrc=aw.ds&gad_source=1&gad_campaignid=20391226981&gclid=Cj0KCQjw3K7RBhDJARIsAKRtP5SaCv4gs2S4tKARqqxdpJv6Z9YjDjwrcMtxnrVBTjpV--yQGxyyH1oaAokEEALw_wcB

 

[firebirdparts]

Will general normal ground contact 4x4s last that way? I did that with my shed, but I ended up needing like 10 bags for one hole.

If you think that will last, how big of a hole and should I go with 4x4s or 4x6s?

I find digging post holes is really pretty easy and honestly, 100 pounds of quickcrete is plenty. If you put 10 bags in a hole, then just dig a smaller hole next time. 24" down and maybe 12" diameter, with a 4x4 in it, will consume maybe 2 50 pound bags. The posts don't last forever, but when they rot, the building won't go anywhere. I'm not sure how much uplift protection you're really gonna need. If a tornado comes "close" there's a point where this will all make a difference. Closer, it won't. Farther away, it won't.

Where I live, you can park a shed on a half dozen cap blocks and they do fine.

 

[Hank11]

Two girl bags per hole is enough if you’re real accurate with your holes so that you can have a nice square building. A girl bag is the 40 pounder that they sell at the big box store. The man bag is an 80 pounder and I’m too old to be a man anymore in regards to concrete. Six posts might be better for a little more substantial 12 foot wall.

I don’t think I’ve ever had a pole in concrete in the ground rot from the concrete, but more right at the junction of the concrete and air. That’s usually where the rot starts. And you’re gonna cover this over and build a building around it so I don’t think it’s gonna be exposed much. Your buildings liable to last 20 or 30 years just like this. I’ve worked on a couple of old barns that people remember being there when they were little kids and they were old. The cedar or locust posts were still fine, just set in dirt.

I’d set the poles in concrete in the ground, then build a base band all the way around it out of some kind of synthetic material — something like Trex deck boards. Dig and scrape the dirt to give a nice snug fit. This will give you a chance to keep your siding up off the ground, so it won’t rot so fast.

1 X nailers will let your siding lap over the Trex base band. Add structure as you see fit to make your wallet happy.

 

[bas157]

My sister needed her shed anchored to the ground (local code). Pretty sure the shed builder dug a hole, drop a chain in it that was bolted to the subframe of the shed and dumped some bags of concrete in the hole with chain. That was enough for the township for anchoring purposes.
I'm not in tornado alley, but around me, all the sheds have 4x4 runners just sitting on 3/4" modified stone beds

 

[Sanderguy777]

Ok, i have found something I think will work. https://www.menards.com/main/buildi...otection/4660pp/p-1642874344541647-c-5713.htm

This thing allows me to just set the post into concrete solely (I think. I will call them tomorrow to check). If i can do that without issue, I want to know if the following idea would work.
I want to make a teardrop or tall pyramid shape hole with a 12" top hole, and a 16" wide base about 2 or 3ft deep. I would put 12" of concrete in the bottom, then add the post with the protector installed, and then backfill the hole with dirt after. This would save a bunch of money on concrete from 12" piers 3ft deep and still offer a 16" diameter footing.

Would this work, or is this a terrible plan?

 

[Hank11]

You are way overthinking this and you’re just building a small shed. Concrete is gonna be one of the cheapest parts of this build, even by the bag it’s cheap. And you’re not buying that much. If I was gonna spend extra money, I would spend it on getting posts that are treated to go into the ground.

 

[Sanderguy777]

You are way overthinking this and you’re just building a small shed. Concrete is gonna be one of the cheapest parts of this build, even by the bag it’s cheap. And you’re not buying that much. If I was gonna spend extra money, I would spend it on getting posts that are treated to go into the ground.

I am getting treated posts. Critical structure ground contact, even. But I want it to last.


That said, I did some more digging (LOL) and found that I could just use these in the ground without any concrete, just packed dirt and things.

To be fair, I do think you're right that it would be fine. I had an 8x8 chicken coop in Idaho and the winters there ROUTINELY saw 60mph or higher winds. I know we had 80mph at least once. That thing never moved an inch and it just sat on the ground with nothing. This shed has WAY more cover (that coop was in a field on the edge of town with 0 cover on 3 sides).

Nothing below ground would probably be fine, but I also want it to last really well, so I think these protectors will do well. That said, this is protected on all sides by large trees and fences and houses, so just a shed sitting there would probably be fine.

 

[rsanter]

Are you over thinking this? Yes you are. It’s a small shed

foundation? Do a drypour concrete foundation, Or do concrete stepping stones, or do compacted gravel.

then use a treated 4x4 as the wall base and regular 2x4s for the rest. Just sit the thing down on the foundation base you have and your are done. If you even need to move it you can. If you need to anchor it to the ground then use earth anchors.

 

[Sanderguy777]

Are you over thinking this? Yes you are. It’s a small shed

foundation? Do a drypour concrete foundation, Or do concrete stepping stones, or do compacted gravel.

then use a treated 4x4 as the wall base and regular 2x4s for the rest. Just sit the thing down on the foundation base you have and your are done. If you even need to move it you can. If you need to anchor it to the ground then use earth anchors.

That's what I'm thinking now. I'm going to look up a drypour foundation, that sounds interesting.

However, I imagine I'll end up with a tarp under 2 or 3 inches of gravel and 4x4s that the building sits on. Basically skids, but parallel to the walls and under them.