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Posted: Sat May 26, 2018 12:03 am
by marcelm
Hi all,
This is my first post, having discovered this extremely interesting and useful site.

I would like to lay a rectangular patio covering most of the external space. The house wall is on the short edge, and a retaining wall on the other short edge, about 5m away. The sides of the patio on the long edge would border a 300mm flower bed down the left and right sides. I am concerned about drainage on the patio as the flower beds may not be sufficient soak aways.

The house has a drain pipe that comes down from the gutter, going straight into the ground.

I have read that the patio fall needs to be away from the house, which is in the direction of the retaining wall, but there is nowhere for the water to drain there.

I was wondering whether installing a drainage channel finished against the house wall with the patio fall towards the house would be acceptable. The channel could then be spiced into the storm water system to discharge water. An alternative is to create a transverse fall in the direction of the flower bed, installing the drainage channel perpendicular to the house along the long edge of the patio.

Do either of these suggestions have merit, are they permissible (building regs) and safe as I don't want to create a damp problem? Suggestions favourably received.

Posted: Sat May 26, 2018 7:37 pm
by seanandruby
As long as your below damp either option has merits. Does your soil drain ok? Dig a 300 deep trial hole and fill with water then monitor if it drains away.