Linear drainage to patio

[jackpot]

Looking at getting the garden done for next year so now in the process of planning and designing. So far im looking at a new patio area about 5m x 3m onto the back of the house. To the rear of the patio (paving slabs) im thinking about a raised bed on either side of either sleepers or some sort of softwood timber. The beds will be long enough to leave a gap in the centre of about a metre. This will form the access to the main garden area. If this is the case then the surface water is obviously going to run down the fall into the side of the raised beds, so im thinking of a linear drainage system to run along the full length of the patio or in two parts for each part to run alongside the raised beds only and leave the centre part free to avoid the kids walking and possibly damaging it.

Im thinking of different ways to doing this properly but also dont want to create unneccessary work. I can work out to lay the linear drainage but then what?

1. Is it best to connect this to an existing outside gulley. If so how?

2. Could i leave some sort of trench after digging out the earth to be filled with hardcore and geotextile for the surface water to drain into the ground. And finish off with decorative aggregate to bring the trench upto slab level so any water will drain through the aggragate and hardcore before it hits the sleepers. (Read this somewhere and not sure its possible or will work). Also sounds like making more work too.

3. Would it be even silly of me to think of a slight fall towards the house. There are to gulleys to the back of the house and would be much more simple to lay the linear drains here going straight into the gulley without any additional pipework etc etc.

Ideally i would like the first option to do the job properly but just after a few alternatives if possible.

 

[Thermo]

what type of soil are you on, do you have any problems with drainage in that area at the moment?

 

[jackpot]

Not sure about the soil. Drainage is not a problem. On very very heavy down pours there has been puddle in the garden. But ive only seen this once or twice a year and it soon drains. There is an existing patio there now which was not put down properly so slabs have sunk a bit. The only pools of water on the patio is when water gets trapped due to sunken slabs but generally it just drains down onto the grass at present and not been a problem

 

[Thermo]

in which cae you would be fine to simply leave a margin between the slabs and the sleepers and backfill with shingle. the water will soak away through there.

DOnt slope it towards the house.

you could use drainage channels, but it sounds like it will be overkill.

 

[dextrous]

I agree with thermo. If you are worried about possible waterlogging then you could dig a couple of small soakways (approx 30cm cube, infilled with rubble) under a part of the span of the sleepers and line the space between the sleepers and patio with levelled guttering with outlet notches into the soakway area, and cover this all with gravel to hide it from view.

 

[Thermo]

if its free draining now then i doubt there will be any need for soakaways.

 

[dextrous]

if its free draining now then i doubt there will be any need for soakaways.

Agreed - just giving an alternative for the op to mull over if he wishes and is worried about concentrated run-off from 15 square metres of patio..

 

[jackpot]

Thanks guys.

So if i extend the patio area for digging to incorpprate this margin for drainage, would the MOT do the same job as the shingle? (With decoratative stones to bring flush with patio. or would i need to frame off after digging to put the MOT down, lay slabs etc then remove frame and insert the shingle into the margin left followed by the sleepers.

As im writing im thinking about bits of much, leave etc getting clogged in the decorate stones and shingle/MOT, so im guessing doing it seperate will be best to enable a geotextile to protect from this clogging.

Have a just answered my own question?

 

[Thermo]

just take the mot up to the sleepers and infill up to the height of the patio with decorative shingle. you dont need fabric

 

[jackpot]

Thanks a lot

 

[jackpot]

Back with another question.

Upon looking at the patio closer, the existing one has been laid about 100mm from the house wall. This extra gap has become filled with soil and collects stone and bits of rubbish. Anyway it does not follow the 150mm rule (More like 90mm and slabs only bout 40mm although 100 mm away from wall).

So im thinking of making this all a feature and laying slabs 200mm from house wall and sleepers all around patio, like above top up with decorative stones.

All easier enough so far but on this wall is a gulley with the down pipe from the roof to allow roof water drainage. The downpipe goes right down the gulley but there is also a void with a cover on it (Grid). The gulley has been formed of concrete. The gulley (void) itself does not serve much purpose as no water drains down there and is full of soil. The only drainage is from the down pipe which goes quite deep.

Anyhow to lower the gap to get a 150mm drop i will more than likely need to cut some concrete from the top . In theory all ok, but im concerned that when digging out for the actual patio the gulley will collapse. Am i being over cautious as i want to exactly plan this out first so it runs smoothly. Im hoping it wont need touching or only a bit of concrete taking off the top using an angle grinder or similar but i wont know the full extent of the concrete holding the gulley until i start digging.

Sorry for the long post, just trying to get a clear picture across.

 

[Thermo]

if youre digging out, then why not remove the gulley and get a connector to connect the pipe directly into the pipe taht will be below the gulley. it will look much neater.

you dont need to be 200mm from the wall, if you leave a 100mm gap and backfill with shingle it will be fine