Damp wall near floor

[Searto]

Hi All,

I have a damp issue that I'm struggling with. It started on an internal wall near the back door about 30cm from the floor or perhaps behind the skirting board. We have tried clearing the gutters which seemed to help for a bit but now it has come back with a vengeance. It stated forming semicircle patches up to a third of the way from the floor and has now starting coming from the other side of the wall to meet in the middle. It's also making it's way in on the other side of the door.

We sealed a crack in the UPVC that ran all the way up with silicone but it still keeps getting worse. We dug up part of the gravel trench next to the building which which I thought may be a french drain but there is no pipe in there (but lots of soil mixed in with the gravel). There also appears to be chunks of what looks almost like a skirt made or mortar that has fallen off round about where the DPC is that runs under the door outside.

It's 1960s terraced house. I've uploaded some photos.

Has anybody seen something like this before and could offer some suggestions please?

Many thanks

 

[JohnD]

In this pic

https://www.diynot.com/diy/attachments/img_7581-jpg.202813/

There is a lot of water in the ground making the wall wet long term. The presence of the adjacent pipe suggests a leak. Is the pipe original? What is it for? Stand back and take some wider pics please. The white marks suggest soap from a washing machine.

Where is the DPC?

Has the ground level been raised since the house was built?

How much higher is the floor than the ground?

Dig out that gravelly trough. Is it wet?

 

[Searto]

Hi John,

Many thanks for the reply. This outer wall forms part of an extension which we think was built in the 90s. The pipe to the left of the soil stack is for the dishwasher just the other side of the wall. The pipe to the right goes through the house into the utility room which does indeed have a washing machine. It is also used for the waste from the sink in the downstairs toilet.

I've marked where the DPC is with the red line on the new photo. I can't see it on that side but on the other side of the door there is a section where it is visible.

I don't think the outside ground level has been raised but I can't be sure given that there has been an extension added on.

The internal floor is about 15cm up from the patio slabs.

I've dug the chunk of gravel out that you can see on the photo and it is quite damp.

During dry weather it doesn't seem to get any worse. When we get rain, that's when we notice it get worse.

I don't know if it's worth mentioning but you can just about see, the outlet of the gutter pipe empties into the larger section of gravel so this trough probably gets a lot of water when it rains.

Many thanks.

 

[ted456]

You have rising damp at lower levels - and appear to also have penetrating damp coming in from around the door frame at higher levels.
The channel/French drain and the sand and cement plinth are attempts to deal with the rising damp.
The plinth could be bridging the DPC - but detailed pics would be needed to confirm that its bridging, plus the occupants were already having damp problems previous to any S&C plinth.
The channel is possibly an irrelevancy.

All affected plaster to be hacked off and replaced with 4:1 Sand & Lime render.
Check all along the wall at interior low level for damp signs. Remove and check all the skirting.
Can you move all units etc out of the way?

The wall cavity might be blocked at low level - blocked with debris from the original build.
Close up pics of the frame jamb/silicone seal would help.

What the square down pipe is discharging into is wrong.

Read the related threads below use the search facility for more info.

 

[foxhole]

Looks like all your problems caused by rainwater discharge which cannot be accommodated by a French drain which is only for local water not designed to take the rain fall from your roof .
No rising damp.

 

[JohnD]

the worst of the damp appears to be at the point where you have scraped the stones away.

Dig that out more with your gardening trowel.

It is so close to the soilpipe and wastepipes that it might be you have a leak in the ground

It looks to me like the gravel is more a decorative feature than a french drain.

Or it might just be the rainwater downpipe which does not appear to discharge into a drain and will overwhelm that patch of gravel. Where do the gutters from your house discharge?

Have you ever seen wild tomato plants, or red worms, nearby?

 

[Searto]

No wild tomato plants but there were grey worms in the gravel.

You're correct, the downpipe just discharges into the gravel and the gutters discharge into the downpipe on the last photo.

Does this mean that whomever built the extension didn't install adequate drainage?

Thanks all for your replies so far.

 

[JohnD]

So it would appear, unless it has sunk into the ground or been covered over.

If there is no rainwater drain nearby, I suppose you could bury a soakaway in the garden or under the shed. The size can be calculated or estimated by a local builder according to the size of the roof and the absorbency of the soil, but I have no knowledge of how it is done, or if Building Regulations approval is needed. It is surprising that this was not done when the extension was built. You might be able to get a copy of the plans via your local authority website (if approval was in fact obtained).

Grey or pink worms are no problem, but red brandling worms are often found around broken drains. They thrive on organic material.

 

[ted456]

foxhole, fwiw:

"all your problems caused by rainwater discharge" - no, they are not. The penetrating damp high up the reveal has nothing to do with the French drain.

"No rising damp" wrong again. Any moisture rising in a wall is known as rising damp - and the pics show rising damp.

The French drain (as i explained above) was dug as an attempt to deal with damp after damp issues were noticed inside the room.
The plinth was installed for the same reason.

 

[JohnD]

are the waste pipes (washing machine, dishwasher etc) buried in the floor, or visible above? Are the damp walls near them? I can't see a pic of the inside walls showing these semicircles (the source of damp is usually in the centre of these)

If buried in the floor, can you examine the floor beneath its covering and look for signs of damp? Also round the edges by the damp walls.

I expect you are going to say the floor is covered in laminate flooring and impossible to uncover.

It usually is

 

[ted456]

Searto,
Why not show more pics of all signs of damp along that wall - or anywhere else in the extension?
Can you post pics showing the roof of the extension at the eaves/gutter?
If you post a pic of the main rear elevation then maybe a way of taking the extension down pipe water could be worked out?
Is the extn a single story with a flat roof?

 

[Searto]

Hi Guys,

I don't think there will be an easy answer to this one by the sounds of it. I try to fix things myself usually but I think I'm out of my depth on this one! Think I'll have to get the pros in...

Will keep you guys updated.

I really appreciate you taking the time to try and help me with this, thank you!

 

[foxhole]

foxhole, fwiw:

"all your problems caused by rainwater discharge" - no, they are not. The penetrating damp high up the reveal has nothing to do with the French drain.

"No rising damp" wrong again. Any moisture rising in a wall is known as rising damp - and the pics show rising damp.

The French drain (as i explained above) was dug as an attempt to deal with damp after damp issues were noticed inside the room.
The plinth was installed for the same reason.

Don’t agree

 

[Searto]

Hi All,

As promised, I have an update. I had an independent damp surveyor round to look at the issue.

The damp was caused by a leaking internal pipe fitting near the outer wall. The leak was very minor but has been happening over a long period of time causing saturation of the internal floors and walls approximately 1.8m into the building (tested with a damp meter). This has caused the green patch of moss on the outer wall.

Remedial action:

• Fix the leak!
• Remove the damaged plaster by the door reveal on both sides and instead use 2mm 3:1 render with water proofing additive and leave a 10mm gap at the bottom.
• Paint the backs of the skirting with gloss enamel before fixing them back to the wall.

He also noted that any exterior dampness below the DPM is of no concern and that the plinth on the outside is serving no purpose and can be removed if so desired.

As a side note, whilst cleaning up the exterior, I found the drain for the downpipe covered in stones (and yes, I feel like a prat now...). I'm going to clear all that up properly and get the gutters cleaned (I do the lower one on the extension but there is also one high up on the main part of the house.

Hopefully this will all get the damp sorted!

Many thanks all for the feedback.

Take care