Use waterproof membrane??

[scadding]

All the prep work has been done for my shed base and all that remains is to pour the concrete. I've laid and compacted hardcore, sub base and some sand to tie everything together.
I was intentending to lay a pond liner on top of the base, before concreting, to act as a waterproof membrane.
Is this recommended or is it more important that the concrete is poured directly onto the hardcore so as to solidify the compacted base even further?
I would appreciate your views on whether the waterproof membrane is more important than pouring the mix directly onto the hardcore.

 

[noseall]

It will make no odds as to whether you use a dpm or not unless you intend using the shed for something more salubrious than a garden shed.