Paving Slab Base

Martynt74 · 27 Mar 2018 at 10:09

I think i know what i'm doing but wanted to check with you lot who know much more than me!

My mother in law is in the process of choosing a wooden "summerhouse". It's likely to be around 10'x12'

On Sunday i started digging up the grass and trees etc for where it's going to be going. There are a load of pebbles covering one section which i planned to pour into my hole along with some broken up concrete for use as a hardcore mix. Hopefully this will be strudy enough.

I've picked up a pile of paving slabs off facebook for free which will go nicely under the structure but after a lot of reading i seem to have less of an idea about the next step.

On top of the pebbles i was just planning on piling a load of sand with some cement mixed in. Then lay the paving slabs on top of that (they're 900x600 beasts) and point it up. Although some websites i've read seem to suggest making more of a wet mortar for the slabs to lie on and using a range of mixes of sharp/building sand and cement.

I think some of the techniques will vary depending on if the slabs are used for a patio with a lot of footfall and weight in different areas compared to my needs of something level with a fairly even weight distribution.

Could anyone give me some pointers.

Cheers

BigBoy · 27 Mar 2018 at 11:14

Hardcore needs to be a good 10cm deep and fairly stable so mix it with some 10mm to dust hardcore for best results. A semi wet mix of cement and don't bother pointing the slabs as it will allow for drainage, I would dot and dab the slabs down rather than full on slab of concrete below them to increase drainage or the bearers of the summer house will rot quite quickly (leave 1cm gap between the slabs). You might also want to think about putting some 3x3 bearers down and then some DMP between the bearers and the summer house floor supports, I did this for my shed 3years ago and no signs of damp or rot yet.

DXP55 · 27 Mar 2018 at 14:19

Also try and make the slab base slightly smaller than the shed - you need the rain that runs down sides to drop on ground rather than slabs - that way under the shed will always be dry.

kinobestew123 · 27 Mar 2018 at 15:54

BigBoy said:
Hardcore needs to be a good 10cm deep and fairly stable so mix it with some 10mm to dust hardcore for best results.

At this point, would it be best to not even bother with the slabs? 10cm of hardcore properly whacked flat sounds like it is going to give pretty good drainage for bearers.

BigBoy · 27 Mar 2018 at 17:48

Yeah it would be stable but not all that nice to look at, slabs are just a topper, personally I dug peers into the ground then filled with 10mm to dust and slabbed on top to hide the hardcore. Thus Thus stability but costs less to install.