# Leveling a concreate slab for a shed



## transatlantic (9 Oct 2017)

Ok - so half of my back garden is a concrete slab. It is not completely flat or level. I want to put a shed on it. Ideally I would pour a new smaller slab onto the existing one that would be perfectly flat and level. But for reasons, I can't do that. My plan is to just shim the bearers to give me a level surface for the shed to sit on. It won't need shimming by much, I think 40mm max on the one side, and then graduallying having the shims fall off towards the other.

So how would you go about doing this?

My plan was to attach the required shims onto the extreme edges of the bearers as necessary, and then spend many hours (with a mitre saw?) adding the inbetween shims or varying sizes.

Is there some kind of existing product that would make this easier for me? it's a 10x8 shed, so there will be quite a few shims!

I've seen the plastic shims for windows and laminate flooring, but they're on the small side


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## skipdiver (9 Oct 2017)

You will need to raise the timber off the floor because water will run beneath it if the slab extends out from the sides of the shed. Slate is good for packers in that situation, preferably bedded on a bit of sand and cement to level them.


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## stuartpaul (9 Oct 2017)

I was thinking folding wedges but the slate and cement approach is probably a better one. 

Would also be a fairly easy way of levelling a bearer. Set the two ends level and when its gone off use as many intermediate points as you want and simply bed the bearer on them to level all.


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## Lons (9 Oct 2017)

Waste of time imo using wood for packing, it will rot away eventually with obvious consequences. Slate with some mortar to keep it in place as suggested is the best solution and easy to do, common practice in the building trade, I've just done exactly that to pack up a couple of concrete lintols

Bob


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## MikeG. (10 Oct 2017)

I would never in a month of Sundays put a wooden shed directly on a concrete base , let alone a concrete hardstanding extending beyond the shed's walls. If you can't/ don't want to build a brick plinth, how about putting it on PCC lintels or fence posts, laid on a strong mortar bed to get it level?


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## Woody2Shoes (10 Oct 2017)

+1 for shimming with slate and/or strong mortar. But...

+1 for MikeG's comment - I think you ideally want to arrange a situation where all timber is a good 150mm off the concrete base. For example, you could create a small plinth(s), or even little dwarf/sleeper walls, on which the bearers ("plates") are then bedded (on a DPC). A good way to do this would be with a couple of courses of engineering bricks (with strong mortar) - you could adjust levels with varying mortar bed thicknesses - a bit like the sleeper walls supporting a suspended floor: 

https://www.practicaldiy.com/general-bu ... ooring.php see fig 1 and 2 etc.

or maybe:

http://clients.junction-18.com/beep/gro ... ide-06.png .

Cheers, W2S


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## transatlantic (10 Oct 2017)

Thanks for the comments guys. When you say slate, do you just mean normal roof tile slate that I can buy at a local builders merchant? 

Like this? https://www.travisperkins.co.uk/Estillo ... m/p/763823

wouldn't that just crack with the weight of the shed as people use it? I thought slate was very brittle? 



MikeG.":35w5ithv said:


> I would never in a month of Sundays put a wooden shed directly on a concrete base , let alone a concrete hardstanding extending beyond the shed's walls. If you can't/ don't want to build a brick plinth, how about putting it on PCC lintels or fence posts, laid on a strong mortar bed to get it level?



Righto. But as the shed itself comes on bearers, is that not the same thing? .. or do you mean the PCC lintels/fence posts as well as the bearers?


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## MikeG. (10 Oct 2017)

I mean that any timber element of the shed should be raised (150mm ideally, but anything is better than nothing) above the surrounding finished ground level, and with a direct non-pooling route for water that runs down the cladding to get away, and dry off. Further, if you have a deluge of rain pooling in your garden, or a good snowfall, the lowest piece of timber in your shed should remain above it.


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## RogerS (12 Oct 2017)

And mesh all round to keep out the rats ?


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