Paving slabs for a wooden shed base

[DIYNovice1979]

Hello,
I'm laying paving slabs for a small wooden shed base, the base will be around 2m x 2m. I've got some heavy paving slabs to put in place (they're the 60cm x 60cm x 5cm and weigh close to 40Kg each).

How do I prepare the base for this? I was planning on levelling soil in the back garden, then using a dry mix of sand and cement, but I'm not sure whether I need an agreggate/Type 1 base (?) If I do need an agreggate\Type 1 sub base, I'm not sure what exactly to buy from Wickes\B&Q or a builder's merchant.

Some tips would be greatly appreciated.

Thanks,

 

[Cheslea2010]

75mm compacted Type 1 followed by 50mm mortar bed for the slabs. Solid as a rock.

 

[DIYNovice1979]

Hi Chelsea,
For the sub base, would that something like 8 or so bags of

Tarmac Granular Sub Base Mot 1 - Major Bag | Wickes.co.uk

Tarmac Granular Sub Base Mot 1 - Major Bag

www.wickes.co.uk

or this

Charles Watson 0 - 6mm Granite to Dust Grano Dust Large Polybag 20kg | DIY at B&Q

Our granite dust, or grano to dust as it’s sometimes known, is a granitic product that has a fine, gritty consistency, with particle sizes that range from 0mm to 6mm. An extremely versatile product with a wide range of uses, grano chippings are often used to in the production of fine mortars...

www.diy.com

or can I just lay the slabs down on the dirt?

Thanks

 

[Cheslea2010]

For 2 x 2m area you would need 600kg of Type 1, 300kg Sharp Sand, 4 bags of cement. 0-6mm Grano Dust isn't Type 1. This is Type 1

 

[DIYNovice1979]

Thanks for the link, that seems like a lot of material, almost 2 tonnes for a small shed?

 

[Cheslea2010]

?? 900kg is 0.9 tonnes.

 

[DIYNovice1979]

ah, sorry, mis-read that with the comma, I thought you wrote 1,300 kg of sharp sand!

 

[scbk]

If the ground was quite hard anyway you could go for half the amount of material, if it's just for a "garden" shed to store a few tools.
You don't need to use cement, I've laid plenty on just sharp sand

 

[DIYNovice1979]

Thanks scbk, it's for a small bike shed, so yes, I'll likely use less material

 

[johnny2007]

It's only a shed!
Maybe cheaper and a lot easier to get a minimix and do a concrete base, then lay the slabs on it with some wet mortar.
Around my ways the do loads from half ton.

 

[Doitproper]

How much do you want to spend / the time you are willing to invest and how long you want the shed to last ?

As a minimum I would remove the top soil (grass), keeping the soil beneath level and as undisturbed as possible. Make sure it is well compacted (walk over it with heavy steps to compact any loose areas) and fill in low spots. The slabs could be laid on this but using a thin regulating layer of sharp sand will make it easier to create a level surface.

One of the biggest problems will be rotting of the shed base so I would try to raise this off the prepared hardstanding so it remains dry and has ventilation. You could either try to pick up some old block paving or use concrete bricks. For a 2m x 2m shed I would put them at about 500mm ctrs under the timbers forming the base and for good measure a membrane between the timber and brick. Damp proof membrane would be good but any plastic / pvc that doesn’t deteriorate will do the job (old takeaway containers ?).

The tops of the blocks/bricks will need to be level and can be checked using a taut line / string. Put a piece of string across the bricks and it they are not level they could be bedded in mortar to take out any irregularities.

The main objective of the base is to remain stable and flat. In the event you have rubbish soil you would ideally go down deeper and put in some subbase or other fill as others have suggested. Just bear in mind that any replacement material should be well compacted and the removed material disposed off. Also watch out for nearby trees and remove any roots that will be under the shed. However, should there be any unacceptable subsistence (before the shed is replaced) there is always the option to pack out the tops of the bricks to re-level the floor.

 

[Mottie]

I have my 8’x6’ shed on patio slabs on plain sand. Been fine for 10+ years.

 

[freddiemercurystwin]

Agreed, the first shed I built was built on some bricks on some gravel and that was on terrible 'New Build topsoil' it was still going strong a decade later when I moved out, people really do go overboard for some things.

 

[DIYNovice1979]

Thanks, I'm looking for a quick and easy method, ideally £40 - £80 on the base materials. As you've mentioned, it's only a shed after all!

 

[scbk]

We put a small shed in my brothers garden, it's sat on 3 timber bearers, straight on to the grass! jobsagoodun