Drainage advice for small london front garden

[Woollieback]

I recently purchased a semi detached Victorian house in South London which had damp issues on the inside of the front wall. Although the surveyor advised a new chemical DPC, I could see that the level of the front garden was above the DPC. I have now removed layers and layers of old patio, gravel and soil and got the level lower and it seems to have fixed the issue. However I now need some advice on what to do next.

The front garden is not a large area, it's around 1.7m wide and 3.8m long. I want to have it paved as its where our bins and bikes are kept, so this is more practical than gravel. My plan is to slope the paved area away from the house, and have a strip of gravel along the edge, which will be planted with a hedge. Rainwater will therefore run off the paved area and into the gravel section where it can drain away.

To slightly further complicate the matter, there is a small side return that we share with our neighbour and the water that collects on the roof is channeled through a downpipe onto our front garden. The old owner just let this water accumulate at the base of the house. There is no drain installed. The surface area of the side return is around 4 square metres, so it's not a massive amount of water.

In my head, the best way to deal with the water from the side return is to lay a small land drain pipe under the paved front garden section and let it seep out. I would dig a trench, half fill with gravel, lay the percolated pipe and cover with gravel. I'm guessing that this constitutes as a soakaway, and I have read that building regs require them to be 5m away from the property. This is impossible, given the garden isn't even 2m wide.

I would run the land drain parallel with the front of the house, and aim to have it 1.2m away from the building. Would this be suitable to not affect the foundations? I could have it further away, say 1.6m however it would then be under the area of the front garden that the paved area soaks into, so I am worried that in very heavy rain it would concentrate too much water in a small place.

Another option would be to simply let the rainwater from the side return empty onto the paved area and let it run across the paved area.

Any thoughts of ideas most welcome!

[Woollieback]

Following on from my first post. When the house was built the wall was very damp. There was a cement render up to waist high, and the outside level was above the DPC. So the render has been removed, the level dropped and repointed with lime. The walls are now nearly dried out. We will re render with lime in the spring.

One issue I have is that when I dug down, it became apparent that there is not much distance between the two layer slate DPC, and the start of the footings. One level to be precise. Ive included a photo below. The slate isn't that easy to see, but its one brick layer under the air brick.

The soil type is a heavy clay and water sits for quite a long time. I feel I have two options.

1. Block pave right up to the house, angling the water away from the footings towards the pavement. If I do this, what level do I join the block paying to the house?

2. Gravel the area. However I am worried that water will still hang around the footings and not be channelled away from the house

[lutonlagerlout]

woolie it is hard to give advice on stuff like this without seeing the site
however 1 thing I would say is do not dig down too far or you could be undermining your foundations

the ideal thing for situations such as this is a linear/aco type drain so that water cannot sit next to the house

your slate dpc is slightly misleading as that is 6 inches below finish floor level
you will have 4/5 inch joists and 1 inch floor boards on top of that slate

the drain ideally needs to be 2 courses below the top of that air brick

cheers LLL

[Woollieback]

LLL - ah that makes sense now. The level of the DPC had me confused, I never really understood why the victorians put it so low. But its the height of where the joists are that's important.

So if I installed paving at the same level as the DPC, there is little risk that the rain splashing up will get as high as the joist level.

But then I need to ensure that water doesn't pool where the paving meets the house, either by ensuring a good gradient away from the house, or if I'm still worried, install a linear channel flush against the house to drain the water away.