shed slab

[lovemytoys]

I'm looking at pouring a slab for 12x20 shed .would i 4" pour work or waste of time .its going to be for lawn mowers ,hunting eq.im not sure if i would be putting my kubota bx24 in but i might

 

[david12171951]

Depends on your soil, and also if you are planning to put a cmall chain wall in it or not. Where i live i poured a 6 inch slab 14 x 24 3 years ago. No change wall, all 1/2 and 3/8 rebar on 12 inch centers, suppose to be 4000lbs mix with activator in it. I have sand ground but this area had been packed hard from being a previous dirt parking area. I have had mine and many full sized pickups with loads over it, bad drought last year and lots of rain now and the year before. One small crack on the off lip as it tapers down to 3 1/2 inches there and only aboput 9 inches long is the crack. This has No chain wall on it, wish i had put one at least where i drive on and off of this slab. If you are ever going to put any posts or walls on it put a chain wall!! At least a post base where the posts will be.

 

[Rdiel]

I worked for a ready mix co for 24 years and seen it all but a 4" thick floor is all you would need. You would be wasting money to pour it thicker. The key is in the sub-base. Make sure it is good and compacted, use rock instead of sand and get it up high enough where the water will flow away from and not under it. Also a little support in the concrete doesn't hurt a thing, like reinforcement wire or rebar and don't pour it real wet, the more water you add the weaker the concrete but you don't have to pour so dry you can't work with it. So a medium slump is what you want, tell the concrete plant you want a 4 to 41/2 inch slump when you order. You do all that and you can park what ever you want on it.

I also agree with david on a 4000psi mix.

 

[lovemytoys]

I'm going to pour it on virgin soil .i removed a old shed thats been there long time (old out house then chicken coup.i was thinking 3/8 rebar with fiber reinforcement

 

[Egon]

Lay down about six inches of crushed gravel and pour on that. You could also consider paver blocks.

 

[lovemytoys]

paver blocks?

 

[lovemytoys]

6 inches crushed gravel above grade?

 

[reggiejr]

Your on the right track with the rebar and the 4" of fiberglass reinforced concrete.
But as others have stated your base the slab will sit on is very important.
Id have to see the lay of land to tell you for sure but if it were me i would level the sub base and put at least 8" of good quality crushed gravel 12" would be even better than compact.This does two things the added elevation helps shed water away from the slab and it will be a solid dry base for your slab to sit on this will give you minimal movement with the weather changes.@ a foot thick your at 8.88yd's for your footprint.
get 12 yrd's and you'll have plenty to slope away from your slab all around it and that to me would be cheap insurance to avoid future problems with your investment.
A good foundation is the most important thing for the longevity of any structure.
And it would be a good excuse to get some seat time too.:thumbsup:

 

[lovemytoys]

i came up with a little under 3 yards =4"x12'x20'i used a web site Concrete Calculator, Prices and Pouring Information - The Concrete Network

 

[reggiejr]

Yes correct for your concrete im refering to the crushed gravel for your base under your slab @12 inches thick.

 

[bigtiller]

The perimiter of the slab should be thicker than 4 inches to support the weight of the shed. 8" thick and 16" wide should be about right.

 

[lovemytoys]

The perimiter of the slab should be thicker than 4 inches to support the weight of the shed. 8" thick and 16" wide should be about right.

24" or 16" rebar on center?

 

[Duffster]

24" or 16" rebar on center?

24" is plenty with an extra run in the perimeter curb.

 

[wrooster]

I agree with the comments above regarding using a gravel base for the slab. Ideally you'd use a block foundation as well -- but otherwise to support the walls you are going to have to pour thicker at the perimeter and use rebar.

A couple of other thoughts...

1) Make sure the slab is pitched towards the door to a) prevent any water from coming in, and b) allowing water to get out if it does get in.

2) Consider an apron in front of the shed, which allows your project area to "spill out" onto the apron when the weather is nice. This effectively increases the usable floor space when it's not raining/snowing, and therefore you can get away with a smaller shop.

3) Pour a sidewalk-sized area OUTSIDE the shed, along one wall, which then can be used to store implements and other (such as racks for fuel or other seasonal items). It is SO MUCH easier on everything if the implements etc are stored on a flat, clean surface compared to storing them on/in soft mud. The stored items stay clean and hook-up/take-off is so much easier.

Wrooster

 

[Rdiel]

There's a right way and a wrong way and a half fast way, Wrooster has the right way down to a science! Nice work!!

 

[Cat_Driver]

Always add fibers to your Mix. I poured 4" or concrete on beach sand with absolutely no compaction of base and it's been 4 years now and not even a hair line crack.

They put it in at the plant and wasn't that much money. I think they have stainless steel fibers and regular fibers. Aome use fibers instead of rebar

http://66.151.101.31/Images/Polypropylene Fibers in Concrete_tcm45-347135.pdf

 

[lovemytoys]

i like the idea of block wall,but where i live we grow rocks . what I'm looking at thanks to all the help here is12x20 slab with 8"x12"perimeter.rebar 24 occ with extra on the perimeter and fiber . if i did what rooster did the frost line is 3 feet down.my machine is to small to do that.

 

[wrooster]

I forgot one other thing...

Run conduit into the shed before pouring the slab. Run as much conduit as you ever think you will need -- conduit is about $4 per 10' length and is a **** of lot easier to put in the ground when the ground isn't covered by cement. Even if you have no plan for power in the shed now, put the conduit it for when you will eventually want/need power. Then it is a simple matter of pulling the wire and hooking up the ends.

Wrooster

 

[Wnc3]

16" on center , it is not much more $'s.

 

[lovemytoys]

what are the major advantages to go 6 " then 4" 4"pad with a 8"x12"perimiter=4.5 yards an 6" pad with a 8"x12" perimeter 6 yard which isn't a big leap in price