How to build a concrete slab in Ontario?

Question

slab must be 10 x 20 feet to support a metal shed to be assembled on top of it, land inclination is a bout 1 foot over 10 feet and it need good drainage because ground is black heart, metal shed instruction book suggest 4 inches tick concrete. Questions: need drain around? need to cover with geotextile? How tick gravel under? need metal bars in the concrete? Is a ratio 1 part portland, 2 parts sand and 3 parts gravel OK? Best answer might get a contract offer in Oro-Medonte.

Answer 1

That's alot of concrete to mix by hand.  You're looking at 2 1/2 yards minimum.  I would recommend a ready mix truck.  4" is minimum thickness and you don't need metal bars (rebar), but I would recommend wire mesh.  They come in 5' x 10' sheets.  Over lap them about 6".  Don't get the roll type because it's a chore to unroll and lay flat.  You can lay the concrete right on packed dirt, without stones.   I don't know what black heart is.  But 2" - 3" stone over dirt would allow for better drainage and less chance of water freezing and lifting the slab.  I would also have a expansion joint right down the middle and divide the slab into two sections, each 10' x 10',  As far as geotextile, you should dig the ground level to pour the slab and with the level base, geotextile shouldn't be necessary.  But it's use wouldn't hurt either.  Your mix is correct, but again, I would recommend a ready mix truck with a 3000 psi rating.

Answer 2

Very easy, I will give you my opinion on what I would do. I would first prepare the area of which your shed will be going, then I would make the ground as level as possible by using a garden rake. Once done I would then dump around three inches of fresh gravel on top of the surface. Now is where the concrete comes in, the metal bars are optional, they are there only to re-inforce the concrete, but if it is just supporting the shed you should be fine. Get four 2/4's and cut them into the 10x20, once done s***w them together and place on top of the gravel. Then I would get at least 7 bags of concrete mix and mix it with water and pour into the form you created with the 2/4's. Let the cement dry for 24hs then remove the 2/4's and let the cement dry according to what it says on the cement bag, you are done! The gravel acts as drainage so you are good, no need for drainage. good luck...