Concrete Slab On Paved Drive?

durham

Hi Pros,
I'm asked to build a cedar storage shed on top of a driveway. I'd like to have it sit on a concrete pad. I viewed the previous discussions on this site ( both pro & con )re: concrete slab on top of paving, and visited the link about whitetopping. I had in mind to tear it all out, but considering what i've read here on this site i'm giving it second thoughts to place concrete on the asphalt. How would you pros go about it? I'm stuck on "whitetopping" - bonding to the existing asphalt or breaking the bond with a high test styrofoam. I'm in southern ontario , Canada. Shed is 5' x 20'. drive is in good condition. elevation of 4" - 6" for slab is ok. What is your professional opinion?
( if i can save the time/trouble/expense of removing the asphalt...i'm all for it! But... i'm open to suggestions!)
Thanks!

Teetorbilt

I'm from sunny So.FL. Dont you have frost heave concerns there? How about building on pilings?

I've been reading here fore a long time and I believe that you have to go down a certain depth because of the freezing. Others will be along.

__________________
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shanekw1

5' x 20', thats a funny sized shed.. anyway, I'd cut out the asphalt where the shed is sitting, pack the base well, and pour the slab to whatever height you want above the asphalt.

Here in BC, any accessoy building under 600 sq feet can be built on a slab with thickened edges.

durham

...sold.
I'm pulling the asphalt up tomorrow. what size is the thickened slab at permeter?

durham

and it is a strange size. I wasn't invited to the design party!

dlcj

Is wood not an option? Why not just treated 2x4 or 2x6 joist and treated 3/4 ply decking laying directly on the asphault? Shimed up level and bolted down of course. It would me movable and wont be a raised slab left in the drive. Breaking up asphault and pouring a slab seams like alot of unneccessary work for a small storage shed like that.
Also however you do it if the current asphault is not heaving then whey would anything sitting on top?
I think that would be easier to sell to the customer than telling them you have to bust up their driveway for alot more money too.

shanekw1

For a 6" slab I form it with 2x12 and make the trench 16-18" wide with 2 rows of rebar in the trench hung from the slab grid. That is more for a 20' x 20' garage type building, that little shed I'd probably just pour a nice 6" slab with rebar in it.

dlcj

Damn! you guys like to overkill
A footing for a house is normaly about 8x16 (we overkill that to 12x24 and 3 #4 rebars.
And a [nice 6" slab] is good enough for a firestaton with no rebar only rewire. I saw it done and was a fireman there. Floor has no major cracks in 18 years.
Leave out the frost issue and crazy codes and a 3-1/2" slab is good enough for any shed or carport for that matter.