Concrete slab for shed.. Where should I start?

[pokhim]

Hi,

I just ordered a new shed which is 2.35*1.75 and I need to put down a concrete slab as a base, before I put down the bearing and floor etc. The shed will not house too many heavy items.

I am planning on putting down a 3.55 * 1.95 * 0.1 slab. I understand that I need to create a frame using 18mm ply and put down a dpm, then fill it up with concrete.

What is the best way to mix up concrete?
What is the best mix/ratio for my purposes?
Is it best to mix it up in batches in a rented concrete mix machine then pour it in?
How long will it take me to do, if I am by myself?

thanks!!!

 

[oldbutnotdead]

If this is only a garden shed you don't have to put a concrete base down- 50mm council paving slabs on a sand bed will do quite nicely if your ground is fairly solid.

Also have a think about rainwater- with your slab being bigger than the shed, when the rain comes the bearers will end up sitting in puddles of water which won't do them a lot of good.

If you are determined to do concrete then for that size slab (0.7 cubic metres) doing it with a cement mixer will take about half a day and be quite hard work on your own, much easier with 2 (1 mixing, 1 pouring and levelling). Concrete mixes- look on the back of the bag of cement or google it, usual is 1 part by volume cement to 4 parts ballast. Shuttering- yes that's the easiest way to get the slab flat and level. With concrete you ought to prepare a decent subbase (compacted hardcore then sand then dpm) but for a shed it isn't essential.

 

[r896neo]

As said above a few council flags would be more than adequate especially if you lay them on a good thick 50mm bed of mortar. This will reduce your amount of mixing significantly.

A solid concrete slab as you plan will be easier to get right, no need for 18mm ply just use the cheapest timber you can find as long as its straightish and stake it at intervals to keep it straight.

Consider getting a price for readymix as it may not work out much dearer than buying the materials you need to mix yourself especially if you have to pay for delivery.