Drainage on side of house

[sidcup7]

I've just removed what I think is called a 'french drain' from the back of our kitchen (see last photo with water butt) – a previous owner had put a drainage pipe in the gulley but used large pebbles to cover it, so over time it became encased in soil and was completely blocked. Our neighbour's drainage is meant to flow into this too, and this was causing her issues . The gulley at the back is now back to it's original state, allowing rainwater to flow into the drain.

But there's a problem at the side of the house. It also had pebbles and compacted mud up against the wall. I dug this up and found it was completely blocking two air vents with damp mud, which would explain the slugs and musty smell we get in the kitchen. Having removed the pebbles and mud there's now this channel but there are no exit points for the water that collects in it.

In the photo with the hosepipe, I thought there'd be a gap in the brick around the drain perhaps, but no. The water just sits in the channel either side of the drain.

What's mean to happen and what should I do? I could put the pebbles back but they just seem to conceal the water and risk blocking the air bricks again. Is there supposed to be a channel, or should I be looking at getting it filled in? You can't tell from the photos but the patio slopes down towards the french doors and the side alley. The channel down the side wall doesn't flow around the french doors and step, because that also still has mud and pebbles. I could clear that away too, but want to know I'm doing the correct thing. Clearing that won't help with the first channel, leading up to the drain.

Any advice appreciated.

Thanks.

 

[Mr Chibs]

Can you see any damp course in your current walls?

The ground should be at least two bricks under this... ie. 150mm lower.
Your stone paving looks to me like it's a bit high, this will be adding to the wetness around. This probably could do with lowering.

The pic with the red broom, it looks like there is a lot of splattering of water on the door cill?
Have you got leaky downpipes/guttering?

Air vents need to be unblocked if your floors inside are suspend... wood joists etc.
They need air flow on at least two sides if not all.

Out of curiosity, can you remove the guttering grate, or is it covered over by the slab? It shouldn't be if it is.

Starter for ten if nothing else.

Proper French drains are perforated pipes usually with membrane wrapped round them.

Blocked bit of downpipe is a bodge.

 

[sidcup7]

Thanks Mr Chibs.

I can see the damp course on the end wall and at the correct height, so I'm hoping/assuming it's there all round. The muddy doorway is just me (and the cat) coming and going over the weekend, and I think our guttering is okay. The guttering grate by the water butt, I can remove. There was no sign of any membrane around the perforated pipes, so maybe that's also why they blocked up.

I think you may be right about he paving, it is quite high and could have been laid over an existing concrete patio or something. But lowering it sounds like an absolute nightmare. I'd be out of my depth and lack funds for anything professional at the moment.

Would finding a way to channel that water down the side of the house into the kitchen drain be an option, or does the rain drainage have to be kept completely separate from kitchen drainage?

Thanks.

 

[Mr Chibs]

You might want to have a look at this post.

Pebble trench next to house

You can cut back the patio it's the easiest way to deal with high paving, without having to remove it all.

You will need an angle grinder etc, but this is a DIY job.
Some put French drain/pipe in the trench, but you may not actually need this.

Do you have lots of standing water in heavy rain?

 

[sidcup7]

Thanks again, Mr Chibs. We haven't had a lot of standing water out there, but I fear that may be because water could have been pouring in through the two air bricks. I've added a photo that shows the 'trench' a bit clearer, and circled one of the air bricks that was previously completely submerged by compacted pebbles and mud. The vents in the bricks were packed with mud too, so I hope that might have limited the water a bit but we do have some damp in the kitchen around that area.

From your advice in that pebble trench thread, it sounds close to what we currently have – the upper stone layer of patio is 6 inches back from the wall, creating this 3 inch deep channel. But the base of that channel is hard cement or concrete, and there's nowhere for the water to escape at either end. Now that I've removed the mud and pebbles, rain water does pool and sit, but eventually sinks through the cement.

So could I just put a thin layer of pebbles back, making sure they don't cover the air bricks, or do I need to cut out the hard base, so the pebbles are sitting directly on earth, not cement, so the water drains into the soil below? Thanks.

 

[Mr Chibs]

Ideally you'd need to remove the sub base and some soil (at least a bricks depth worth) sit the pebbles on directly on the soil.

Have a good clean of the air vent remove any debris that is blocking it, you may want to remove the vent to clear anything behind it.
It will be mortared in, but maybe loose.

 

[sidcup7]

That all makes sense, and I should manage that! Thank you so much.