Concrete Shed Base Help and Advice Needed Post your questions and get answers regarding all areas of drives, pathways and patios

[JohnP]

Hi all, my first post here so I hope this is in the right place. I really need some advice from someone that knows what they are doing with laying a concrete shed base:
Im putting a 10ft by 20ft shed in the garden, we've had some guys round to replace some fencing and thought as the shed base is a huge job for me to do on my own I'd ask them if they could do it. It's been done today I wasn't at home but my wife took some pics while it was being laid that has made me feel quite concerned.
The quote for the Base 20ft x 10ft was:

Four men for one full day
mix 2 to 4 tonnes of concrete and level
reinforced steel mesh throughout
Water retardant through each mix
10 year guarantee (i would expect this to still be there safe and sound in 20+ years)
£1200

I saw them this morning before I left and they said that they had ordered premixed concrete that would be pumped in, but realised that they were going to have to do it by wheel Barrow as the pipe was apparently only 5 meters long. I asked about the steel mesh and he said he had ordered concrete with fibre in that didn't require the mesh, which was the modern way to so it he was told by the supplier when he ordered it. Apparently it cost more but it would be at his cost.
There was a previous concrete shed base which looked fine which was approx 12x6 which they left intact to pour on, I asked about hardcore under the remaining part as much was soil, and was told it didn't need it and it was fine.
I was a bit surprised when my wife sent me this photo that she took before they'd poured the concrete.;

IMG-20160721-WA0001-600x800.jpg

To me it looks like they've added rubble to reduce the amount of concrete they have to move with the wheel Barrow, it looks like the concrete would be a bit thin in places also the rubble is way to close to the edges. My thought being when the frame comes off you'll potentially even see the rubble in the concrete. I mentioned this to my wife on the phone and she said she'd asked about the frame and they said the frame stays on!!! Surely this is not normal it's on the ground and will rot?! Also the stakes for the frame I can see are on the inside so they'll be gaps in the corner if it's taken off.
I wasn't expecting the frame to stay in place, is this normal or even acceptable in any way? My challenge now is its done and I don't see how they can rectify this without ripping it up and starting again, obviously going to cause an issue with the builders. I hope I'm making an issue out of nothing but would really appreciate opinions on this.

[welsh brickie]

They have not done the work as quoted, the thickness of the concrete is an issue, Fibres in a concrete mix, does not replace reinforcing mesh, the mesh is for structural reinforcement and it is what you were quoted, The concrete needs to be a minimum of 100mm thick on well compacted hardcore for a solid base.

[JohnP]

Thanks for your feedback, having measured it, it's also the wrong size, 2 inches short on width and length. It's also not square with just over 10 inches difference in diagonals! They've said they'll make it right, although I would have thought of the pour and extra 2 inches on one side or an inch all-round it's just going to crack and fall off the edge? The top of the concrete is far from smooth or level. Apparently they are going to skim the top to smooth it as it's hard to get it right on a shed base that big first time around. Feeling like I need to argue that they should rip it up and start again. Any idea how much 4 tons of pre mixed concrete costs (delivered in a mix truck)?

[welsh brickie]

get them to remove it, bodging the job by adding extra concrete wont work. Cost of concrete will depend on the area,
You can have it barrowed in, in our area Mixamate do it, don't know if its a national company though