Waterproof membrane for planted bed next to house - Urgent info request on waterproofing

[timjax]

I'd really like help on two questions:

- What kind of waterproof membrane should we use to protect the house from a new planted bed? The background is that we're building a patio with sawn sandstone paving over 100mm Type 1 and 40mm sharp sand or sand/cement at only 20mm-40mm below the floor level inside the house , and taking care to make sure the paving falls away from the house. There will also be two slot drains adjacent to the house to catch any nearby rainfall, but we need to have a small planted bed (1.5m long, and about 60cm wide) as well. We don't want this planted bed to wick water into the house.

There's also going to be a planted bed running 3m along the side of an extension protruding from the house the back of a terraced house. I assume we should try to put in a waterproof membrane here also -- and I'd like some advice on what we should use and how it should be installed.

We're hoping to do the work tomorrow, and I'd be really grateful if anyone can help out today. Thank you!
:p

[lutonlagerlout]

you are in far too much of a rush fella
40 sharp sand? fail
any bed should have the soil 150mm below DPC ,if this is not practicable then there should be a physical gap of 100 mm from your house wall
when your extension was built was a cavity tray installed to allow for the high paving height?
slot drain PITA if they get blocked,linear drains much more effective and easy to maintain
photo pls
LLL