Stone Border - Improving Drainage?

danny_ryan95

Hi Guys,

Over the next 6 months I'll be installing a solid base to put a hot tub on and also having a patio installed. The base and the patio are going to to be surrounded by 30cm wide stone area borders, and the whole garden will also have this border.

Below is a reference point just to give an idea. The picture is to scale, all the yellow bits are stones. We're not looking at putting any vegetation in the stone areas. The garden is elevated, with a small retaining wall at the front.



The garden is on a natural slope towards the house. As such water should run towards the front from the sides. And excess water should run down towards the front stones. I'm thinking of making it so at the back, water runs to the sides so that it can then move to the front without entering the grass. I thought maybe some sort of waterproof barrier to prevent it leaving the stones onto the grass.

Obviously stones have better drainage than grass, but my main query is, does anyone reckon this will help the rest of the grass? I don't really want to dig it all up and install a drainage system quite yet, it's a New Build so standard New Build issues really.

Fairygirl

I hope I've got this right @danny_ryan95 
Is the white area all grass and is it at the same level as the surrounds at the moment?
How does the grass do just now - is it getting enough water?

I'm not sure it would do much good to try and put in a barrier, but it would probably depend on how good the drainage is already for your lawn. 

danny_ryan95

Yes the white area is all grass. It is all roughly the same level, the odd minor deviation which allows some water collection, but overall all a steady incline away from the house.

It gets more than enough water as is and regularly becomes waterlogged. It's had a detrimental affect on the overall health of the lawn.

The overall premise is the hope to redirect water from the lawn into the stone areas. 

Fairygirl

Ah - ok. I know - new builds can be a real pain. The problem is that the prep isn't done properly before turf gets laid. 
I'm not sure diverting it will work. Water has to drain through the grass/soil vertically, and if the drainage is poor, that won't happen. Short of lifting the whole lot [which some people have had to do] the best method is continuous spiking and aerating. There are tools which remove a core of soil completely [a bit like a giant bulb planter] and then grit can be put down that. Not something I've ever done, but it supposedly helps. If the soil's clay, it can be a thankless task trying to keep the drainage right though. 

The other solution is a French drain, which is similar to what you're think of doing. 

danny_ryan95

I get that water has to drain downwards, but if I used a damp-proof membrane under the stones, any water on the stones would drain towards the front of the garden and sit in the stones until the weather improves and it can evaporate. The ground immediately underneath the stone beds would be drier, which could maybe help if the rest of the ground is saturated?

Ideally I wanted to put something like half pipes down the side of the garden under the stones but the wall at the front has nowhere for the pipes to drain to, so it would be sat in the stones. 

Essentially I want to prevent any water that ends up on the stones from getting back to the turf, which I think I can do pretty easy. Whether that alone will help the remaining turf I'm not sure, and moving water from the turf to the stone areas seems more complicated.

Fairygirl

Ah - I see what you mean. I expect that would work quite well for those areas at the sides then. I don't know what kind of membrane you intend using, but take a look at pond liners - there's often sales on some of the good online suppliers like Bradshaws and Pondkeeper etc, and that stuff is great for all sorts of things.

Can you make holes in the retaining wall at the front to get a pipe in there? Most retaining walls should have gaps or pipes to allow for excess water to drain away, so that seems unusual. 

danny_ryan95

I'm hoping the stones at the side will improve the garden as a whole by hopefully trying to redirect water towards stones.

I've attached a picture of the wall.

Fairygirl

Are those concrete gravel boards? If so, they might have enough gaps for drainage 

danny_ryan95

Not sure what they are, but they're concrete. I always thought they were just solid concrete walls just dropped into place. 

So if I got the water to sit infront of the concrete, it'd potential drain through?

Fairygirl

It should do. 
It could still be worth getting a few drainage holes in them at some point, but maybe wait until you've had the work done and see. Perhaps the people doing the work could advise, and maybe do them?

danny_ryan95

I guess I could sit the gravel on top of some sort of reservoir for the water to sit in, and drill 2-3 holes the size of a standard drill bit to allow slow drainage from the reservoir. 

Do you think that overall this might help the rest of the garden?