Foundation for shed/patio ?

Haket

Hi, what kind of foundation would I need for a garden shed 16ft x 12ft (metal). It'll hold benches/tools and 3 motorcycles (max 200kg each).

I've been advised everything from

2inch of concrete on top of the topsoil
to
6inches of concrete with 4 inches of compressed stone under that.

I also want to build a patio area and use paving slabs as access to the shed, would a few inches of sand/cement mix do ?.

yop

If i was doing the same I would take out all the topsoil, could not be that much, fill with hardcore stone, then put your dpc, pour your concrete foundation.

At least you can be sure that your foundation is solid and it will not crack or cause rising damp.

Haket

Whats a dpc ?.

Seems a lot of groundwork for something that would weigh not that much ?, but I suppose there is a "right way" and a " eh, good enough way" :-)

Aidanm

dpc = damp proof course.
Stops rising damp.

Haket

Ahh oh, I had planned on that before pouring the concrete. I reckon I'll need 2cublic meters to cover that area.

Can I get that amount delivered from Roadstone etc ?

GreeBo

Yeah, they should deliver that to your house.
Also make sure that you dont try to pour too large an area at once.
Try to divide it into 3 (or more ) sections, otherwise it might crack on ya as it settles.

for the paved area I would just do as you say, paving slabs onto a sand cement mix.

Haket

Would 16ft x 12ft be considered a large area ?.

yop

It is a big enough area, to do it right it is. Do not do it right and you may have cracking or subsidence.

As said do it in 2 or three sections. Split with a piece of timber to divide the sections.
I presume you are going to bolt the shed to the ground. Make sure that the concrete is deep enough to hold the bolts.

Victor

Make sure there are no pipes, drains or other services under the shed.

Originally posted by Haket
2inch of concrete on top of the topsoil

Waste of money. It would crack within weeks and crumble in a few months. Even a garden path would be 4-6 inches

Originally posted by Haket
6inches of concrete with 4 inches of compressed stone under that.

This is more like it. Ideally strip off the top soil for at least 6 inches (or more if the is a lot of plant material there at 6 inches), backfill with 6 inches of well compacted (hire a vibrator from a plant hire company) broken stone and 6 inches of concrete. Increase the concrete at the perimeter to 12 inches. For the size you want, you could get way with one slab, or alternatively create a joint along the short axis (a simple way to do this is to use heavy duty DPC). Adding some light reinforcement would be an advantage (A193, 50mm above the bottom of the concrete).

Originally posted by Haket
I also want to build a patio area and use paving slabs as access to the shed, would a few inches of sand/cement mix do ?.

Ideally strip off the top soil for at least 6 inches (or more if the is a lot of plant material there at 6 inches), backfill with 6 inches of well compacted broken stone and 2 inches of dry sand/cement mix.

Give me a shout if you need anything more.

Villain

Put some steel mesh in the foundations to prevent cracking

Haket

Thanks for the responses peeps. Time to get digging now I suppose :-)

pythag

whers the best place to get concrete and roughly how much would you need..

i want to do a section at the back of the house.. roughly 22ft by 38 feet
of which half will be used for a shed/studio?

if i want to lay a foundation over this area at 4/6 inches deep how much concrete would i need? who delivers concrete and roughly how much would it cost?

can anybody point me in the right direction?

cheers


pythag

Haket

This is a thread from the past !

> whers the best place to get concrete and roughly how much would you
>need..

I ended up getting it from Roadstone (IIRC)

http://www.roadstone.ie/products/RMix/Ready.htm

>if i want to lay a foundation over this area at 4/6 inches deep how much >concrete would i need?

I ended up using about 1/2 a load of cement for a 20ft x 14ft slab, approx 4-6inches deep. Applied over compacted gravel. The cement truck came to my house and we barrowed the whole lot in about 30mins. Its been there 2 years now and is perfect.

>who delivers concrete and roughly how much would >cost?

I think it cost be about 200euro (but it was cheaper than list price).

mark

TheDriver

I put literally a skin of concrete (1/2 ") after digging it level and then got shed put up on blocks and no cracks or anything and no weeds most importantly.