Patio sloping towards house

30 Mar 2008
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Harrow, London
United Kingdom
Due to the patio level being one brick course below the DPC, building control has suggested an ACO drain (or similar) along the full length of the wall to minimise splash back, something like this:


I should point out that the wall is a new cavity wall with a cavity tray, so splash back is not such a big concern.

Given that i will have a drain along the wall anyway, is it ok to have the patio slope towards this drain, i.e. towards the house? The alternative is to do the conventional thing and slope it towards the lawn. Pavingexpert recommends this for widths no more than 1.5m, but imy patio will be 4mx8m and that's a lot of water flowing straight onto the lawn! I realise i could have another drain along the lawn edge as well, but that would be excessive and ugly!
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It could be argued that having a cavity wall,, it's not so desperate an issue, but you can' guarantee what's going on inside the cavity, so water could track across, but may not. It's down to you if you bother with the drains, but as you say, sloping the patio away from the house will cause a lot more disruption. If you do install the drain, can you feed it into the surface water drain. Running the water dow into the garden, even if you need to install a soakaway (and you'd prepared for all the cost and hassle) would be better for the environment, as too muc surface water is adding to the general flodding problems.
Yes, the idea is to either run the water to a new soakaway, or to the surface-water drain which is easily accessible. Given that the soil in the area is quite clayey, i'm not so keen on the soakaway option. Anyway, i know the contractor will try to avoid it (to save money), and the BCO has as good as told me he would turn a blind eye (as, technically, it's not his duty to worry about where the surface water is going as long as it's going)! Although he did say the water authority could have an issue with it, but how would they know?
Then it's totaly down to you, but it looks as though you've pretty much made up your mind.
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Yes, really just wanted to check my idea wasn't stupid, and that there weren't any consequences i hadn't considered!
I did it last year, and there's been no problems, so I can't see what could go wrong. I wasn't very impressed with the corner joins, so check carefuly on the type you get, but you should be fine.

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