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.