Sorting drainage between patio and house

[Sparrowhawk]

The patio laid to sell the house is level or slopes gently towards the house, and between the house and the patio is a 10cm x 10cm shingle filled drain, that at one end is connected to a soakaway. The wall is getting more stained and the paint coming off the render, and in heavy rain I've seen water reach the airbrick.

 

Water sits on top of whatever this membrane is and drains slowly, usually off the edge by the house.

 

I dug a section out today and the shingle was pretty full of earth and earthworms. I washed this shingle and put it back in without the membrane on top.

 

I'm guessing I need to clean all the shingle in this way so it will let the water drain quickly. Is there anything else I should be doing? Do I need to put strips of membrane back down?

 

And what about the render? I understand it's unusual to have render across the DPC.

 

 

[joe90]

Yes washing the shingle is the right thing to do, if you replaced it with bigger, round stone it will drain faster. I don’t see the point In the membrane. 

[Conor]

Good call ditching the membrane, it's basically a silt trap and causing the mud to build up. 

[twice round the block]

Shouldn't the patio be 100mm below the level of the air bricks?

[Sparrowhawk]

In one place it looks like roots have come through, against the house wall. Do I pressure wash this, push the small roots back through and then pack the hole with mortar? Or does it need more than this to sort?