New drainage connection advice

[saveasteading]

@markcand I posted much the same same simultaneously. 

[Russell griffiths]

Looking at that bigger picture then the land at the top of the retaining wall has been built up too high in my opinion allowing the water to naturally drain off the top and down the face of the wall. 
 

get up the top with some gardening tools and cut back all the crap on the fence, scrape back any soil and sit and watch, I bet the mucky area in the corner is the natural run off from above. 
 

I would want a drainage channel or a sort of spoon drain up top to prevent pooling water up there running down the face. 
sort that bit first. 
 

the cracks I’m afraid will be very expensive to fix and I would live with them for the minute 

 

the small hole has not been filled since the wall was built and is just an easy escape route for water that is behind the wall. 
 

sort the top first then let’s see what happens. 
 

get a pressure washer on that corner so it’s clean and you can monitor it. 

[saveasteading]

1 hour ago, Russell griffiths said:

a drainage channel or a sort of spoon drain up top

A professionally designed wall would have drainage behind it including at the base, so that water never builds up. 

Yours seems to be reasonably stable considering, so applying the various methods above is likely to suffice

[Nickfromwales]

Forget trying to fill the cracks from the face, I believe the phrase applicable here is “pissing into the wind”.

 

If you want the wall to be ‘pretty’ then fit some horizontal battens and some vertical cladding, timber or synthetic, as then the water can dribble out of the new drip holes and down to the ground, behind the cladding. That’s perfectly fine, assuming the walls been there for x number of years and there’s no notable movement of it from its original cast position? 

[slystallone]

6 hours ago, markc said:

To do this right you really need to be excavating behind the wall and installing drainage to take the water away rather than through the wall. A pored wall of that size really should have had the drainage installed, any chance there has been other work at the ends possibly blocking the drains?

Drilling holes will reduce pressure and water level but then you will be managing the water on the good side of the wall - with pipework

What kind of drainage would be behind the wall if it was done in the way you mention rather than through the wall?

[slystallone]

3 hours ago, Nickfromwales said:

Forget trying to fill the cracks from the face, I believe the phrase applicable here is “pissing into the wind”.

 

If you want the wall to be ‘pretty’ then fit some horizontal battens and some vertical cladding, timber or synthetic, as then the water can dribble out of the new drip holes and down to the ground, behind the cladding. That’s perfectly fine, assuming the walls been there for x number of years and there’s no notable movement of it from its original cast position? 

Ya there is no movement 

[slystallone]

3 hours ago, saveasteading said:

A professionally designed wall would have drainage behind it including at the base, so that water never builds up. 

Yours seems to be reasonably stable considering, so applying the various methods above is likely to suffice

Can you give more details on what that drainage would look like behind the wall please?

[markc]

21 minutes ago, slystallone said:

What kind of drainage would be behind the wall if it was done in the way you mention rather than through the wall?

Hi @slystallone, the wall shoulld have the soil side waterproofed with a perforated pipe running around the bottom “French drain” style and backfill with pea gravel, pebbles or similar to allow any water behind the wall to go down into the perforated pipe and then away around the side.

idea is to take any water away to prevent the wall from being a Dam and being subjected to water pressure. It would be worth doing a bit of digging at the wall ends to check for any existing drainage that may have been blocked etc.

failing that you are looking at water management which means a lot of digging or back to cutting holes in the wall and then collecting the water to take it away in visible pipes on your side, 

Edited Tuesday at 15:48 by markc

[saveasteading]

1 hour ago, markc said:

a lot of digging or back to cutting holes in the wall

Exactly so.  The former would cost £10k for a job half done. And is it your land?

Holes £500. A heavy duty core drill with diamond core cutter can be hired for £150 or so.

You could join your outlet pipes up to drain away tidily, or make it a natural water feature of moss, slime and ivy.

[Nickfromwales]

1 hour ago, saveasteading said:

Exactly so.  The former would cost £10k for a job half done. And is it your land?

Holes £500. A heavy duty core drill with diamond core cutter can be hired for £150 or so.

You could join your outlet pipes up to drain away tidily, or make it a natural water feature of moss, slime and ivy.

I'd recommend a TCT percussion SDS drill vs diamond core, as that'll be 'soggy' and a total bastard to core drill multiple holes in.

 

Not so bad if you can hire a diamond core drill with a hose pipe attachment to allow water to flush the hole whilst it's being drilled. May need both, if you hit a bit of rebar as the TCT SDS won't like that very much whereas the diamond will whizz through it.

[slystallone]

On 09/12/2025 at 17:06, saveasteading said:

Exactly so.  The former would cost £10k for a job half done. And is it your land?

Holes £500. A heavy duty core drill with diamond core cutter can be hired for £150 or so.

You could join your outlet pipes up to drain away tidily, or make it a natural water feature of moss, slime and ivy.

It's my land. 500 to get someone to do it? Also on your last point about joining up outlet pipes, how do you recommend to do that?

[saveasteading]

1 hour ago, slystallone said:

joining up outlet pipes,

If you use bathroom drain pipes, then you can join them with junctions and bends, either down to a drain or angled across the wall.

[saveasteading]

2 hours ago, slystallone said:

500 to get someone to do it

Doubtful. £500 for the gravel. Add pipes, membrane, digger, and the earth has to be taken away.

Anyway, how deep and where would you take a drainpipe?  

[Russell griffiths]

Before you start any ideas about drilling into this wall you need to actually figure out what the problem is. 
start by clearing the top area and all that growth that is obstructing you getting a clear understanding of what is going on. 
 

it is clear from the picture that the water is running over the top of the wall, it should not be, so figure that out before knee jerking and drilling holes in an otherwise perfectly good retaining wall. 

[saveasteading]

4 minutes ago, Russell griffiths said:

an otherwise perfectly good retaining wall. 

Agreed. That's a start and may solve the water thing.

Maybe that's enough, but my concern is that it is a wall by a builder and not technically designed. 

I guess if it is ever overloaded by the land above it won't collapse just crack or rotate.

 

@slystallone if you do that, where can you take the drainpipe from the end of your new trench?

 

[slystallone]

3 hours ago, saveasteading said:

Agreed. That's a start and may solve the water thing.

Maybe that's enough, but my concern is that it is a wall by a builder and not technically designed. 

I guess if it is ever overloaded by the land above it won't collapse just crack or rotate.

 

@slystallone if you do that, where can you take the drainpipe from the end of your new trench?

 

Where are you suggesting the new trench? On top of the wall underneath the outlet?

[saveasteading]

3 hours ago, Russell griffiths said:

start by clearing the top area and all that growth that is obstructing you getting a clear understanding of what is going on. 

as @Russell griffiths says. first tidy it all up.

 

I have no idea where the outlet could go. We don't know the site or circumstances.  That's why I'm asking you if you have any ideas or more information.

I have been presuming you might dig out 600mm to 1m and have  a pipe at the bottom of that, so water would run to an end and from there you need to take it elsewhere or it won't drain the area. What is on e land you took the photo from? ie to the inside of that fence. Is it your land? 

And is there more retaining wall between the fence and the house?

 

Not wanting to be rude but it's always worth checking... are you following the logic of building a drain and getting the water away from behind the wall?