DIY block paved driveway, what drainage?

[lasors]

Hello all,

We're having the kerb outside our house (terrace) dropped and we're adding a paved area for parking, replacing grass. I'm doing this myself to keep the cost down, and it will be quite ambitious for me.

The soil is heavily clay-based. We have no downpipe on the front of our house, the gutters drain down the front of next door's house and I'm aware we can't drain our driveway off the property, which makes me think a drainage channel might be a problem. I think the house is too old to have had the underground utilities mapped.

The paved area will be circa 36sqm, which slopes down to the house from the pavement. Between the edge of the paved area and the house will be left an area of perhaps 3-4sqm of flower bed. I'm aware that planning permission can be avoided if the pavement run-off drains naturally to a bed, but am I likely to have any problems doing this? I plan to perform a drain down test on the soil, to see just how bad it is. If not particularly good, would it be a good idea to dig the bed out to a shallow trench and fill with gravel to improve drainage? I know I can't go too deep close to the house, and this only really works if the water will drain away at all, if only slowly! I don't need a pond!

Thanks for any advice.

 

[PrenticeBoyofDerry]

Do you have a problem now with drainage?
Block paving are pourous, so the effect will be the same.

 

[lasors]

No, no problems now, but then it's all grass. Block paving is considered non-permeable is it not? So there's bound to be a lot more runoff, downhill towards the house.

I guess it's nigh on impossible for anyone to guess whether the ground will cope with it without testing it. However, it's hardly a car park I'm building, maybe I'm being overcautious!

 

[mointainwalker]

@lasors

Unless the shallow trench you propose digging actually penetrates to permeable soil below the clay layer, I cannot see that what you propose does anything other than create a slightly bigger reservoir for the run-off

Since your new surface will be non-permeable paving ( I agree with you there ) and then earth compressed by both tamping the paving and passage of tyres, I would expect the run-off water to flow towards the house both far earlier ( from when it starts raining ) and far quicker than it currently does.

If you go ahead, I would certainly suggest digging down in front of your wall and putting in some of that stiff plastic sheet/roll that is sometimes used on new-buils to to protect underground walls .

 

[lasors]

I thought about the plastic sheet idea, not on the walls of the house but on the wall of the trench so the water can only go down into the ground and not further downhill towards the house. Sounds like a bodge perhaps, but no sure what else to do.

Could I bore a few holes in the bottom of the trench to penetrate more permeable layers underneath, and fill them with gravel to stop them collapsing?

 

[PrenticeBoyofDerry]

You do know, if you are installing a drive/parking area and it slopes in to the street, providing the material used is porous, it's okay.

 

[mointainwalker]

@PBD

I don't think any council would accept any sort of block/paving as porous no matter what the material was because:

a) They would have to check and judge each one
b) Any porousity would be much slower than earth and inevitably far
more run-off would end up in the street/gullies which they don't
want/can't cope with.

@lasors

Do you know how deep you would have to "drill" ? Anyway , you've said you intend to dig a test-drain, so this is getting a bit in front of itself.

 

[lasors]

It doesn't drain onto the street, but the other way.

I've no idea how deep to drill, it was merely an idea at his stage. When I get a chance I'll dig a measured hole, fill it with water and time its escape. Hopefully this will give some idea of what the soil can cope with, based on average local rainfall over the driveway area.

It might all be overkill but I don't want to do it and find pools of water at the foot of the external wall requiring the drive to be ripped up immediately.

 

[PrenticeBoyofDerry]

From 1 October 2008 new rules have applied for householders wanting to pave over their front gardens.

You will not need planning permission if a new or replacement driveway of any size uses permeable (or porous) surfacing which allows water to drain through, such as gravel, permeable concrete block paving or porous asphalt, or if the rainwater is directed to a lawn or border to drain naturally.

If the surface to be covered is more than five square metres planning permission will be needed for laying traditional, impermeable driveways that do not provide for the water to run to a permeable area.

Elsewhere around your house there are no restrictions on the area of land which you can cover with hard surfaces at, or near, ground level.

However, significant works of embanking or terracing to support a hard surface might need a planning application.

If you live in a listed building, you will need listed building consent for any significant works whether internal or external.

 

[lasors]

Thanks PrenticeBoy, I've read that before, which is why I am hoping the bed will be enough to drain away the water, as a naturally permeable area. If not, it means an expensive installation of drainage pipework.

 

[noseall]

Ordinary block paving is not porous.

Permeable paving is.

Even gravel will clog up eventually.

Either you build a proper soakaway or look into ways of using existing run-off alternatives and thus seeking planning permission.

I don't care what anybody else says, putting a bit of gravel gravel in a channel or trench will not work and will eventually clog up unless you build a proper job.

 

[Thermo]

spot on noseall. Unless using specifically designed porous block paving systems, with the porus sub-base material, it will not be classed as porous by the council.

Despite that nor,al block paving will allow a certain amount of water to saok through its joints, but you still need to deal with teh majority of the surface water. For that surface area you will create a fair amount of water that will need dealing with, especially if it is sloping towards the house.

You need to be looking at a 1m x 1m x 1m soakaway as a minimum if it will drain away freely from there. What about any planted beds at the side of the driveway to help with disposal of the water

Drainage is not expensive to install at the time of doing the drive. Ripping it up to re-do it is

 

[WabbitPoo]

You are leaving a flower bed, aren't you? As long as you drain into it then you wont need PP. Unless you are on a load of clay this will drain OK one would imagine.

 

[mointainwalker]

Do you reckon 4 m2 of flower-bed on clay can reliably drain 36 m2 of paved area so he's not going to have a lake in front of the door ?

 

[noseall]

You are leaving a flower bed, aren't you? As long as you drain into it then you wont need PP. Unless you are on a load of clay this will drain OK one would imagine.

Drain an entire drive into a flower bed

You are kidding?