Rising Damp After Driveway installation.

[Asad]

Hi all,

 

I’m looking for some advice on a rising damp issue I’ve been dealing with.

 

We had our driveway installed on august 2021 but in april or may 2023 i decided to paint the room with lighter colour and then i noticed damp. 

 

The problem seems to be related to my driveway being too high, which caused moisture to rise through the walls. After several attempts, my contractor finally moved the bricks 4 inches away from the wall, removed sand, and exposed DPC and about half of the brick below.

 

They also added gravel as part of the solution.

 

The contractor believes this will resolve the issue, but I’m not entirely convinced. Is this enough to stop the rising damp, or do I need to expose more of the brickwork or DPC? Would it be worth considering anti-damp injection treatment as well?

 

I was thinking of getting infrared heater to dry the wall but I'm not sure if that is good idea? I have dehumidifier running 24 hours.

 

I’d really appreciate any advice or similar experiences from others who have dealt with this type of problem.

 

I can upload pictures if anyone wants to see.

 

Thanks in advance!

[ProDave]

Pictures?

 

You probably need to cut the tar back a lot more than 4 inches away from the wall, dig out to well below the damp proof course and till with stones.

 

Did the contractor not notice the DPC?  did he say it would be okay?  What discussions did you have about this?

[Redbeard]

10 hours ago, Asad said:

Is this enough to stop the rising damp, or do I need to expose more of the brickwork or DPC? Would it be worth considering anti-damp injection treatment as well?

 

No, don't even consider DPC injection!!! Everything worked well (as far as you have said) before the builder put a hard surface above your DPC. All that needs to be done is to remedy that locally.

 

As @ProDave said, probably take another half-block away so that you have a 'trench' of 200-225mm wide.

*However, what is retaining the edge of the driveway? Assuming it is a standard block paving job and bedded in sand then probably, 'as-built', the house wall will have been the 'retainer' which stops the sand running out from under the blocks, and the blocks 'drooping'. If this was the case, then removing half a block as the builder has done, and another half as we have suggested, could (if no other method has been provided) lose you your 'edge restraint' and gradually the sand could wash away and your blocks drop 'into the ditch'.*

 

The Building Regs require a minimum 150mm (6 inches) between external ground level and the DPC. That is based on an assumption that rain will 'bounce' 150mm max. No-one has told the rain where I live that it is only allowed to 'bounce' 150mm, so it goes for 300 instead! At very least you should revert to the former (we hope) position, of a minimum 150mm down from the DPC to any surface.

 

Ideally you need a soft surface (the gravel will do), and it needs to be far enough away from the wall that rain won't bounce onto the wall above the DPC. In certain wind conditions, your 4 inch (100mm) gap won't be enough to stop rain hitting a block and yet still being able to wet the wall. 

[saveasteading]

All good advice.

Where does surface water go? Towards this wall or away from it?

Keep your gravel lower than the drive so that it can hold water until it soaks away.

 

The gravel will need cleaning every year or so but this is easy.

[Asad]

3 hours ago, ProDave said:

Pictures?

 

You probably need to cut the tar back a lot more than 4 inches away from the wall, dig out to well below the damp proof course and till with stones.

 

Did the contractor not notice the DPC?  did he say it would be okay?  What discussions did you have about this?

 

I am new home owner and I have absolutely no idea about things like building work or dpc. I recently found about dpc after searching about the problem on Google.

 

The contractor should have known this to be honest since this is their daily job. 

 

The contractor is a very rude chap and he only started to comply after I warned him that I will complain to all trade platforms such as checkatrade.

[Canski]

I'd fill that with gravel ( more granular shaped than round) now sloping down to the house but with a roll of DPC against the wall up to the house DPC. It's not the best job but maybe the least disruptive way out of this. 

 

You are correct he should have known better  

[Nickfromwales]

27 minutes ago, Asad said:

The contractor should have known this to be honest since this is their daily job. 

 

The contractor is a very rude chap and he only started to comply after I warned him that I will complain to all trade platforms such as checkatrade.

It is unbelievable that anyone came and did this job this way. The driveway should have been excavated out to drop the top of your new driveway down to the original finished level, with at least 100mm of MOT1 or other sub base material down under the new block paving. Shocking. 
 

Glad you pulled him over this, and that you pushed back. I bet there’s a lot of people who’ve had the same issues and have not gotten anywhere. 
 

The bad news is, you’ll have to pay someone to pull the last 5-600mm of drive up and relay it where the last couple of blocks are set into a concrete / mortar haunching. This will otherwise all start to move about and go south very soon. 
 

Then, as said, clear out about 150-200mm below dpc and fill with decorative colour matched chipping to allow water to fall to ground away from the brick wall.
 

Might be a good idea to paint on some “black jack” (liquid damp-proofing membrane) to go belt and braces. Just stop that about 50mm above DPC and paint anything showing with the wall colour paint. 

[Temp]

47 minutes ago, Nickfromwales said:

It is unbelievable that anyone came and did this job this way. The driveway should have been excavated out to drop the top of your new driveway down to the original finished level,

 

Sadly all too believable. I reckon they hope to be long gone before problems show up.

 

Anyone considering having a driveway or paving done should seek advice here. The Paving Expert web site is also good (see the index).

 

 

[Nickfromwales]

https://www.pavingexpert.com

 

👍🫡

[saveasteading]

Show it to your builder perhaps. Some of these guys are strong and don't mind the weather....and that is about it for suitability. Maybe with knowledge he will improve.

[Asad]

The contractor added this gravel and he left extra bag for me.

 

Do you guys think I should dig bit more deeper to expose the second brick under dpc? Or should I make it more wider than 4 inch. 

 

Also inside the house, how do I dry my wall? Is that going to happen automatically and slowly? I was thinking of infrared heater to speed up

 

Thank you everyone for your suggestions. If the situation does not improve I will surely leave a very negative feedback for the contractor.

[jayc89]

Is it just the pic or is the drive sloping towards the house? If so, you probably want a channel drain in front of the house, rather than just gravel. 

[Asad]

Water flows down to the path

[Redbeard]

3 hours ago, Asad said:

Do you guys think I should dig bit more deeper to expose the second brick under dpc? Or should I make it more wider than 4 inch. 

 

9 hours ago, Redbeard said:

As @ProDave said, probably take another half-block away so that you have a 'trench' of 200-225mm wide.

*However, what is retaining the edge of the driveway? Assuming it is a standard block paving job and bedded in sand then probably, 'as-built', the house wall will have been the 'retainer' which stops the sand running out from under the blocks, and the blocks 'drooping'. If this was the case, then removing half a block as the builder has done, and another half as we have suggested, could (if no other method has been provided) lose you your 'edge restraint' and gradually the sand could wash away and your blocks drop 'into the ditch'.*

 

The Building Regs require a minimum 150mm (6 inches) between external ground level and the DPC. That is based on an assumption that rain will 'bounce' 150mm max. No-one has told the rain where I live that it is only allowed to 'bounce' 150mm, so it goes for 300 instead! At very least you should revert to the former (we hope) position, of a minimum 150mm down from the DPC to any surface.

 

 

3 hours ago, Asad said:

Also inside the house, how do I dry my wall? Is that going to happen automatically and slowly?

Yes, it will be slow, but it will begin as soon as you have moved the 'pre-conditions' as described above. I'd leave it to do its thing and use the de-humidifier you referred to.