Different levels between driveways
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bmcginley
- Posts: 1
- Joined: Sun Aug 29, 2004 9:57 pm
I am currently excavating an area I wish to put down block pavers and I see that they must be laid at least 150mm below the DPC. My problem is that to do this there will be a large fall between the existing tarmac driveway and the new area which I would like to be able to drive on. Also some of the drains are only about 6 inches below the dpc which means I would have to dig them up and relay them deeper which they probably should be anyway !! Currently there is a gravel strip around the house with concrete slabs laid and I think that I will have to keep this gravel strip and start the soldier course from the edge of this. Or would it be possible to lay a linear drain against the wall of the house with a gap of maybe 10-20mm and a membrane in between ?? Your thoughts would be much appreciated
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Nigel Walker
- Posts: 190
- Joined: Sun Aug 22, 2004 7:28 pm
- Location: Cumbria
- Contact:
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Nigel Walker
- Posts: 190
- Joined: Sun Aug 22, 2004 7:28 pm
- Location: Cumbria
- Contact:
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84-1093879891
Sounds like a bit of a nightmare, this one. Let's take on problem at a time...
1 - the level diff between existing bitmac and proposed block paving: This is relatively easy to fettle, as you can adjust the paving levels over the last metre or so before the bitmac to create a smooth transition. Obviously, without seeing the site for myself, it's not easy to say just what would be the best way, but it can be done, I know that much.
2 - shallow drains: Digging up the drains and re-laying them may not be as straightforward as you'd like to think. If the invert level downstream is relatively shallow, than deepening the drains at the driveway end will be no use without reducing the invert level further down the line. This really does have the potential to turn into a massive job.
Having said all that, though, if there is a suitably deep invert that can be comandeered, and you have old-ish shallow, salt-glaze pipes, replacing the drainage system while you've got the drive dug up could be worth considering.
3 - The Gravel Strip: I have a deep suspiscion of these splash strips. To put it in Layman's Terms, they're shite, so, the possibility of replacing them with a linear channel is a good idea. This can also help with the levels problem, in that a linear channel acts much as a Dry Channel Arrangement (see the DPC page) and allows you to have paving higher than the "150mm below dpc" rule.
Any such channel would need to be laid on a concrete bed, and as long as the top of the channel and grating is lower than dpc, even if it's only, say, 15mm, then there's no real need to use a membrane liner or to leave a gap betweeen wall and channel.
So: to summarise - ideally, the paving level would be dropped to be no higher than 150mm below dpc, and there'd be a smooth transition to the bitmac. The drains would be replaced and re-laid to a reduced level, and everyday would be sunny. But, if all this is not possible, the linear channel is your best option.
1 - the level diff between existing bitmac and proposed block paving: This is relatively easy to fettle, as you can adjust the paving levels over the last metre or so before the bitmac to create a smooth transition. Obviously, without seeing the site for myself, it's not easy to say just what would be the best way, but it can be done, I know that much.
2 - shallow drains: Digging up the drains and re-laying them may not be as straightforward as you'd like to think. If the invert level downstream is relatively shallow, than deepening the drains at the driveway end will be no use without reducing the invert level further down the line. This really does have the potential to turn into a massive job.
Having said all that, though, if there is a suitably deep invert that can be comandeered, and you have old-ish shallow, salt-glaze pipes, replacing the drainage system while you've got the drive dug up could be worth considering.
3 - The Gravel Strip: I have a deep suspiscion of these splash strips. To put it in Layman's Terms, they're shite, so, the possibility of replacing them with a linear channel is a good idea. This can also help with the levels problem, in that a linear channel acts much as a Dry Channel Arrangement (see the DPC page) and allows you to have paving higher than the "150mm below dpc" rule.
Any such channel would need to be laid on a concrete bed, and as long as the top of the channel and grating is lower than dpc, even if it's only, say, 15mm, then there's no real need to use a membrane liner or to leave a gap betweeen wall and channel.
So: to summarise - ideally, the paving level would be dropped to be no higher than 150mm below dpc, and there'd be a smooth transition to the bitmac. The drains would be replaced and re-laid to a reduced level, and everyday would be sunny. But, if all this is not possible, the linear channel is your best option.