Hi,
I'm reasonably close to starting to lay a patio in my garden. Im a complete novice but Ive been studying this website (cracking site!!) so hopefully am starting to get to grips with what I need to do. I've got a few areas Im unclear on so was hoping for advice from the experts on here...
The image above will hopefully give a good idea of what Im trying to achieve. Im laying random natural sandstone riven flags against the back of the house. Total width approx 11 metres and it will extend out at between 2.2 and 3.3 metres. Im planning on edging it with something such as Marshalls Tegula Deco.
The biggest headache I have at the moment is that the garden slopes upwards from the rear of the house, so that its approx 20cm higher than the DPM at the right hand side edge of the patio. The left hand edge of the patio is pretty much level with the DPM. My proposed solution is to have the patio slope back to the edge of the house and have a linear drain sitting against the house. There is a drainpipe running down the LHS edge of the house so I could in theory connect it up to this.
As Im not going to manage to have the patio sloping 20cm over the course of 2.2-3.3 metres I was going to use something like Marshalls Woodstone (which I am already going to use elsewhere) as a retaining edge.
My questions are:
1. Does this sound sensible in theory or are there obvious mistakes Ive made here?
2. What fall will I need to build in to the linear drain (as its against the side of the house, a large fall over the 8.8m width of the house could be very noticeable).
3. How tough will it be to connect the drain to the downpipe? Worth getting a plumber onto it?
4. Do I need to think about a hardcore sub-base? (not going to have heavy use, its a new build house but Ive left the garden 2.5 years to settle in so hopefully the level will have settled).
Thanks in advance for anyone making to the end of this essay!
Hi doug. 200ml is a lot, you have to think about obstructing air bricks, bridging etc. As i see it you have two options. option one you drag the soil back and terrace it, option two you do a work around as explained in more detail on the sit index (DPC page. ) technically you dont need a fall in linear drainage, it works on hydrostatic gradient. Although you can buy them with an in-built fall. they are easy to connect, no need for the epense of a drainlayer ( although we work for peanuts ). sub- base depends on ground conditions, although it is recommended.
hope this helps.
Thanks for the respose Sean. Does that mean I can lay the linear drain flat against the back of the house with little or no fall?
I've knocked up another quick diagram to show a cross-section of what I think I should do. I've left the linear drain 10cm below the DPC rather than 15 as the DPC page you pointed me to showed a linear drain example that was 7.5cm below. I figured that 10cm was a good compromise and would mean I dont need such severe a retaining edge or fall.
Thoughts from the experts?!
PS. Just realised Ive put this thread in the wrong board. Sorry Tony - any chance you could move it?
6cm is about right over that distance - you would want anything less with sandstone. We usually try for a 40:1 fall in normal applications anyway.
Unless you have a nice hard subgrade (e.g. chalk), you should put in a sub-base - even if it's only 8cm or so.
Putting in a level linear drain and making the connection to the existing pipework is not difficult, you just need the right bits and a fair bit of digging to make room for it all.
