Drainage/guttering cemented-over

Tiiia

Hi all, sorry if this is in the wrong bit - needed advice with a house we're doing up-in short, 3 years ago, due to rising damp issues and rainwater running down the garden pathway splashing the old brickwork, the builder/landscaper at the time installed a drainage guttering system as in the photos, with gravel which mitigated splashback (i think). Fast forward this week, I came back after a trip to realise my mother has had another landscaper in who is sorting garden (which is fine) but who has also started the process of concreting over the guttering because they both reckon rainwater is seeping/collecting beneath, so now I'm in a pickle as to what to do - ask him to remove the concrete or is he right? There is a slight slope/camber on the path, if any experts on such issues could weigh-in, Thanks all! Tia 

martinm1

You need 150mm below damp course to the ground outside.  If it's less then a drainage gully helps.  But instead of shingle why don't they put in a physical Chanel?  Where does that rainwater drain to, it should be a soakaway located 5m away or into a surface water  public drain.  By concreting over the splashed water will get onto the brick leading to damp problems.  This is a common issue with old houses.  The ideal solution would be to drop the path down, but that may not be practical.

ThisIsWeird

Tiiia, 3 years ago there were issues with rising/penetrating damp, thought to have been caused by rain splashback from the path (yes, that can happen) and that this was mitigated by having a channel dug alongside the house wall which was filled with coarse gravel (yes, that is a common solution)?

Q - from installation, did this channel actually solve the problem, or did it continue?

If the former, then why the heck fill in a functioning channel?! If the latter, then a different solution is required, but I'm not sure that filling it in is the answer - and it'll make it a hell of a job to remove once the concrete has set for more than a day.

I can understand the 'idea' behind it - a sloping concrete ledge should help angle the splashback away from the wall (no idea how successfully) and also keep the water flowing down the path away from the wall. But, as pointed out by Martin, the position of the DPC is important, so do you know where this is?

The gravel channel - where did the rain that ended up in there finally go to? Did it feed into a drain, or did it just seep through the ground? If the latter, then I can see why the new landscaper considered it a poor  solution, as it channel presumably just filled up with rainwater, and would then remain partially filled afterwards as it slowly seeped away - not good.

I understand the ideal setup is the gravel-filled channel, but with it also able to drain away quickly.

I cannot 'say' to get the concrete out right away, as I'm not qualified to. But once it sets fully, it could be a real chore.

Hopefully Stu or S62 or others can quickly give you a definitive answer.

Section62

Tiiia said:

Fast forward this week, I came back after a trip to realise my mother has had another landscaper in who is sorting garden (which is fine) but who has also started the process of concreting over the guttering because they both reckon rainwater is seeping/collecting beneath...

Sounds like a case of Chesterton's fence.

What is the exact problem the landscaper thinks he is going to fix by concreting over this area? And does he know whether his proposed solution will do that?

Very likely not.  If there is a problem with damp then you need a professional with the skills to identify the cause and an appropriate solution, rather than a landscaper who 9 times out of 10 are the cause of the problem in the first case.

The gravel has the beneficial effect of providing a surface that raindrops are more likely to penetrate rather than bouncing off onto the wall. It is a standard method of helping to protect the lower part of walls of older houses, especially those with solid walls or minimum DPC.

Your mum and the landscaper need to understand and explain what they think the "seeping/collecting" problem actually is, and what evidence they have that this is any kind of problem which needs fixing.  Otherwise any supposed solution risks making things worse (and that includes replacing the gravel with channel drain).

Phil4432

A French Drain may indeed mitigate the splashback, but as another poster pointed out, where does the water drain to?

If it just sits there, it may contribute towards rising damp. 

However, just concreting it over means that you lose splashback protection.  A builder may then recommend installing a dpc, as with older houses there is no dpc.  However, these older homes were doing fine without a dpc for decades, until a driveway company came along and raised the level of the drive/path, with zero consideration for surface drainage and splashback.

This is a real issue, I've seen homes with driveways literally channeling water into airbricks.

One solution is to have a storm gulley installed next to the wall.  That sorts out surface drainage, but will only reduce splashback. 

I'd say the cheapest solution here may be to get a drainage channel underneath the gravel(French Drain) connected to the drains.

Don't just concrete over the French Drain though.

Tiiia

martinm1 said:

You need 150mm below damp course to the ground outside.  If it's less then a drainage gully helps.  But instead of shingle why don't they put in a physical Chanel?  Where does that rainwater drain to, it should be a soakaway located 5m away or into a surface water  public drain.  By concreting over the splashed water will get onto the brick leading to damp problems.  This is a common issue with old houses.  The ideal solution would be to drop the path down, but that may not be practical.

Thanks very much for your reply. That is worth mentioning to the guy, I know ther eis a damp course underneath, so am baffled why he's concreted over it! I will mention a channel, but it seems like I have to fork over double because of the mistake cheers though !

Tiiia

ThisIsWeird said:

Tiiia, 3 years ago there were issues with rising/penetrating damp, thought to have been caused by rain splashback from the path (yes, that can happen) and that this was mitigated by having a channel dug alongside the house wall which was filled with coarse gravel (yes, that is a common solution)?

Q - from installation, did this channel actually solve the problem, or did it continue?

If the former, then why the heck fill in a functioning channel?! If the latter, then a different solution is required, but I'm not sure that filling it in is the answer - and it'll make it a hell of a job to remove once the concrete has set for more than a day.

I can understand the 'idea' behind it - a sloping concrete ledge should help angle the splashback away from the wall (no idea how successfully) and also keep the water flowing down the path away from the wall. But, as pointed out by Martin, the position of the DPC is important, so do you know where this is?

The gravel channel - where did the rain that ended up in there finally go to? Did it feed into a drain, or did it just seep through the ground? If the latter, then I can see why the new landscaper considered it a poor  solution, as it channel presumably just filled up with rainwater, and would then remain partially filled afterwards as it slowly seeped away - not good.

I understand the ideal setup is the gravel-filled channel, but with it also able to drain away quickly.

I cannot 'say' to get the concrete out right away, as I'm not qualified to. But once it sets fully, it could be a real chore.

Hopefully Stu or S62 or others can quickly give you a definitive answer.

Thanks for your concise reply there - so, according to my brother whose room it affected most downstairs - there was an improvement, less rising damp and the such as he saw it.

 I spoke to the landscaper earlier and apparently the water wasn't soaking away properly, kind of settling in the gravel when he examined the drainage system and was against the wall, hence why he concreted over it as in the pic. He's left the vertical drain uncovered though (circled). 

But you've given me some points to think about there, I will probs need to contact the prior drainage experts to ask. Thanks again

Tiiia

Section62 said:

Tiiia said:

Fast forward this week, I came back after a trip to realise my mother has had another landscaper in who is sorting garden (which is fine) but who has also started the process of concreting over the guttering because they both reckon rainwater is seeping/collecting beneath...

Sounds like a case of Chesterton's fence.

What is the exact problem the landscaper thinks he is going to fix by concreting over this area? And does he know whether his proposed solution will do that?

Very likely not.  If there is a problem with damp then you need a professional with the skills to identify the cause and an appropriate solution, rather than a landscaper who 9 times out of 10 are the cause of the problem in the first case.

The gravel has the beneficial effect of providing a surface that raindrops are more likely to penetrate rather than bouncing off onto the wall. It is a standard method of helping to protect the lower part of walls of older houses, especially those with solid walls or minimum DPC.

Your mum and the landscaper need to understand and explain what they think the "seeping/collecting" problem actually is, and what evidence they have that this is any kind of problem which needs fixing.  Otherwise any supposed solution risks making things worse (and that includes replacing the gravel with channel drain).

Thanks for your reply - so, according to the landscaper, apparently he saw water was kind of partially settling in the gravel when he examined the drainage system, hence why he concreted over it as in the pic above, and my mother agreed as she noticed over rainier days the issue. I did wonder though 'if it ain't broke, don't fix it', but alas it's too late. I'm wondering if I ought to just leave it now the concrete has set and see how we get on! But yes, I have heard older houses have common damp issues like this. Cheers again for your input 

stuart45

The finish on that concrete looks really rough.

Tiiia

Phil4432 said:

A French Drain may indeed mitigate the splashback, but as another poster pointed out, where does the water drain to?

If it just sits there, it may contribute towards rising damp. 

However, just concreting it over means that you lose splashback protection.  A builder may then recommend installing a dpc, as with older houses there is no dpc.  However, these older homes were doing fine without a dpc for decades, until a driveway company came along and raised the level of the drive/path, with zero consideration for surface drainage and splashback.

This is a real issue, I've seen homes with driveways literally channeling water into airbricks.

One solution is to have a storm gulley installed next to the wall.  That sorts out surface drainage, but will only reduce splashback. 

I'd say the cheapest solution here may be to get a drainage channel underneath the gravel(French Drain) connected to the drains.

Don't just concrete over the French Drain though.

Thanks for your reply - yes, I have heard older houses have common damp issues like this. I posted an update pic above to show what the landscaper has done by way of a solution and we have kept that rectangular drain as circled. A French drain is an option; as the concrete has unfortunately set, is there a way this can be unstalled under or should I tell him to remove it and start from scratch to install it, you reckon?

 Cheers again for your input 🤝

stuart45

I'd tell him to rip out that mess anyway, it's such a bad job, as well as staining some of the pavers.