Hardcore or stone?

[paulweller84]

Hi,

I’m looking to widen a parking area by creating a hard standing concrete area where there’s currently a strip of grass. There’s two ways I’ve seen that this can be done.

1. Dig out, line with membrane, fill with big pieces of hardcore/rubble, pour concrete over the top (done this before with a hot tub).

2. Dig out, add type 1 then sand. Place membrane over the top and pour concrete over that.

What’s the pros and cons of these methods, or are they equally suitable?

Picture shows the strip being dug out

 

[noseall]

Not much point to a DPM outdoors.

 

[paulweller84]

Not much point to a DPM outdoors.

I did wonder why it was necessary, but when we built the hot tub base a few years back that’s what I was told to do.

looking at guides on shed bases, they say to use one too.
Is it different as nothing is going to be placed on top?

 

[Munroast]

I think landscaping membranes are good idea under gravel etc to stop weeds coming through, but under a block or concrete drive I wouldn't bother
as for a plastic membrane - I would have thought this would be a poor idea as it would prevent natural drainage.

 

[paulweller84]

I think landscaping membranes are good idea under gravel etc to stop weeds coming through, but under a block or concrete drive I wouldn't bother
as for a plastic membrane - I would have thought this would be a poor idea as it would prevent natural drainage.

I’ve just been reading this guide which says you must use a membrane. I’m confused about which is the right answer here!

 

[^woody^]

Why, oh why would you want a damp proof membrane to stop damp coming up through a slab of concrete that gets rained on 360 days a year?

Likewise, why would you want a weed membrane to stop weeds trying to get through concrete? I can only think of knot weed that will break through concrete and not even a kryptonite membrane wil stop that.

 

[IT Minion]

Isn't part of the idea of a weed proof membrane to be put under hardcore to help separate the two layers and aid drainage? Or am I just making things up now?

Edit: although there won't be much drainage through cement...

 

[cdbe]

I thought the idea of a membrane in this situation was to keep the water in the concrete to ensure it cures properly.

 

[^woody^]

I thought the idea of a membrane in this situation was to keep the water in the concrete to ensure it cures properly.

No. If curing is an issue, a cover is put over the concrete

 

[^woody^]

Edit: although there won't be much drainage through cement...

Nor concrete

 

[paulweller84]

Why, oh why would you want a damp proof membrane to stop damp coming up through a slab of concrete that gets rained on 360 days a year?

That’s kinda what I’m asking here. Why do the guides like one linked above (which is specifically for a hard standing) all seem to say it’s necessary?

 

[paulweller84]

360 days a year?

You must be a northerner then Woody?

 

[^woody^]

That’s kinda what I’m asking here. Why do the guides like one linked above (which is specifically for a hard standing) all seem to say it’s necessary?

What link?

 

[^woody^]

You must be a northerner then Woody?

You insult me sir

 

[paulweller84]

What link?

oops

https://newdrivewaycompany.com/concrete-hardstanding/