New to the forum - advice needed please

[Damian Hemsworth]

Hi All

I'm new to the forum so would like to say a big hello to everyone and hope my stay will be enjoyable and informative.

I've decided to have a go at replacing my old shed which presently sits on a sloping concrete base that must have been laid by a drunk! Either that or one end of the base is slowly sinking (does this happen?)

The area of the existing base is approx 16ft by 10ft and slopes by about 3 inches across the 16ft side. My old shed sits at a funny angle and the door doesn't close properly as there is a large triangular void at the top of the door.

I want to create a 16 ft x 16 ft base in it's place to build a new workshop on, I'm reasonably proficient at DIY and have used concrete before (laying patios and fencing) but have never laid a concrete base.

The area behind the shed drops down about 2.5 ft, my plan was to run a spirit line level across from the highest corner and enclose the entire area with a retaining wall using dense 440mm blocks.

I would then chuck in a bit of hardcore and compress, followed by about 6in of ready mixed concrete and level off.

My question is, would I experience any problems with the new layer of concrete being quite thin as I approach the highest corner? The thickness is likely to be only a few mm thick here.

The alternative is to take out all the existing concrete and level this (within a retaining wall) followed by a layer of concrete (6in) however this is likely to be quite a bit of hard work using a sledge hammer. My project is estimated to be around £2k so I'm hesitant to bump the cost up by hiring tools if I can get by without.

Also, if I was to take the second option, is there any merit in concreting over a reinforced steel grid, Or is this unnecessary?

Any advice would be gratefully received.

Kind regards
Damian

 

[DIYnot]

Welcome Damian, good luck with your project. I will move this thread to the Building forum for you.

 

[Nige F]

Hello Damien ! I was told by a road man once that 50mm is the minimum thickness of concrete for a path to patch over - so you could cut some of the existing out and re do it using the broken concrete as hardcore

 

[theprinceofdarkness]

The angled concrete base and the sloping door should point you to the fact the the whole structure has moved since installation. From what you say is that the change in soil level is at right angles to the slope of the base, but I can't help but think that the two are linked. Has one side of the base been laid on made up ground which has finally settled? Until slope has be understood, piling more concrete and blocks on the earth will only accelerate any settlement and make it more difficult to dig out and sort out.
FWIW
I bought a house with a garage at the end of the garden, the side of the garage was about 2' away from a 4' drop into next doors drive. the garage had a slope in that direction, as the soil under the base had squeezed out side ways partially pushing out the retaining wall. I dug it out and put in 22 piles 4' deep by 9" diam along the edges of the new base with loads of steel and mesh to reinforce the concrete. This mean't that the concrete was like a 22 legged table which was sitting on the stable soil, with the loose soil just sitting under it. New secondhand concrete garage (old one was wood) on it no movement in the 28 years since I did it.
Frank

 

[Damian Hemsworth]

I like the idea but to be honest, if my wife saw that she'd freak out!

I think I'll bite the bullet, dig it up, reinforce and level..... At least I'll have faith that it's done properly! (And the Mrs will be happy)