Existing slab looks to have no DPM

[garindeathray]

Hi All,

I have just moved into a new house that has a very rotted shed at the bottom of the garden that initially just looked to be sat on the ground and surrounded by shingle. On closer inspection it was sat on a 5m x 3m concrete slab:



I can't see a DPM in the slab though:



In the longer term I would like to build a workshop to the Mike G recipe but in the short term I need to build/buy something quick to get all the tools out of an expensive storage unit and the living room - something the wife has mentioned a few times..... The house needs a tonne of work done before I can get around to the dream workshop though

For the quick fix should I just put a wooden base down on some bearers? Do I put dpm down above/below the bearers? Anything else I need to beware of? The exiting shed is in a terrible state:



For the later Mike G style build, will the slab need to be replaced with one with a DPM or can something be done with the existing?

As I live in a conservation area I need to get planning permission to remove / build / replace any garden buildings, which might slow things down a bit

Appreciate any advise

Thanks

 

[Mike G]

A DPM isn't really very important, so long as the top of the slab is above ground level all round, and so long as whatever you build on top of it is raised up off it on a plinth. I'm about to start work on a garage for my place, and there will be no DPM.

 

[Cabinetman]

That’s what I thought, but I wasn’t 100% sure so I didn’t say anything. I presume you have seen the other thread titled garden shed, Rob is using some nifty adjustable feet/keep the wood off the wet base thingies. Ian

 

[Mike G]

......Rob is using some nifty adjustable feet/keep the wood off the wet base thingies. Ian

That's very far from ideal. In a permanent structure you want the lowest timber a minimum of 150mm (6") above the ground or slab.