Patio drainage

[Ian Hill]

Hi Everyone,

I've been a keen follower of this site for a couple of years now and rely on it for all of my groundworks DIY projects, but this time I seriously need a sanity check and some direct advice from the good people here.

I'm in the process of building a raised patio (using Indian Raj Stone) with a retaining wall, (see attached pic) but am concerned about drainage.

The height of the patio will be one course below the french door step and damp course with the wall height eventually raised to 450mm above that. All the rubble you can see is just packing on top of which I intend to build it up with layers of type 1 lime (whacking it down as I go) until I've got to a level for a cement bed for the flags.

In my humble attempt to manage water and damp, I'm running some damp membrane around the wall so that it extends out along the ground about the same distance as it comes up the wall to the height of the patio, thereby creating a moisture barrier between the patio base and the wall. Would appreciate any thoughts as to this being a good idea.

Now to the hard bit - there is a 4" drain running along the conservatory wall (missing at the moment) that connects to an existing soak away and you can see the gully by the door below the drain pipe. What I thought of doing is running some linear drains around the edge, or possibly a central gully and connecting to the soak away pipe.

Am really stuck with what best to do here and would really appreciate your advice.

kind regards

Ian

Patio Photo

[lutonlagerlout]

i would favour a linear drain over a gully every time
not sure what your intention is regarding falls but you need to pick up the conservatory water
so linear drain
LLL

[local patios and driveway]

As tony has said, fit a linear drain at the conservatory wall (spend the money and get those beautiful decorative iron ones it would suit the house to a tee) run the drain in to that bottle trap then the downpipe neatly to the top of the linear drain. Neat tidy and functional. Personally regarding the barrier you plan to install between the house and sub base i see it as a pointless move. If anything it could only serve as a moisture trap preventing the wall to ever dry out.

I await to see if my peers agree

[Ian Hill]

thanks guys, this is really helpful and greatly appreciated. Would there be any benefit from also running a linear drain along the house wall under the french doors and main door ?. The reason I ask is that this wall is south facing and the prevailing winds are south and always drive the rain towards the house, so even though I plan on sloping the patio away from the house, you can bet driving rain will push water back towards it. As you can see its an old house with a new chemical damp course (very suspicious that these actually work), so water and damp is a real headache for me.

[local patios and driveway]

It would help with regards to water bouncing up and over the damp course. Maybe run the linear drain in front of the house instead