Damp Walls advice sought

I’ve got an ongoing problem with damp penetrating through an exterior wall of my house. I had that wall repointed, and then as that didn’t fix it, had it rendered but still the damp persists.
I’m not sure what to do next as the roof is in good order and so are the chimney pots and flashing so remains unclear where the damp is ingressing from.
But if it’s not the outside, do I know need to consider removing and replacing the interior plaster and putting some kind of sealant on the interior wall ?
The house is Edwardian. London brick Built good order overall.
Advice on how to proceed much appreciated.
Thanks in advance.

Are you getting mould in the corners?

Have you tried damp proofing?

We had damp in the corner of our house. Got somebody out who told me it was rising damp and £2k to fix it.

By luck I had left a large bucket in the side return which had filled up overnight. The bloody gutter had been leaking. Not enough to notice anything when it rained, but the bucket overfilling gave it away.

Persevere finding the root cause. It will usually be gutters, bridging or some other water ingress.

It is almost never rising damp and I am not sure that rising damp even exists anyway. Just a ruse to support a whole damp industry selling snake oil.

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Originally Posted by noTAGlove

We had damp in the corner of our house. Got somebody out who told me it was rising damp and £2k to fix it.

By luck I had left a large bucket in the side return which had filled up overnight. The bloody gutter had been leaking. Not enough to notice anything when it rained, but the bucket overfilling gave it away.

Persevere finding the root cause. It will usually be gutters, bridging or some other water ingress.

It is almost never rising damp and I am not sure that rising damp even exists anyway. Just a ruse to support a whole damp industry selling snake oil.

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I’ve recently had a similar issue. Had some work done on the gutters but have decided to see what transpires over the winter before replastering/redecorating.

My Mum had the same issue. Damp in the front room in one corner, near to the chimney. Behind the TV (but oddly no damp on the outside wall).

Had two companies out and they could find nothing (I think they just had a cursory look TBH). Had a third chap come and he took off some tiles near the chimney to investigate.

Lo and behold the plastic liner under the tiles had torn (the house is 70+ years old so might just be wear and tear) and in a heavy downpour, the rain was running into this hole, down the aerial cable and wetting the wall behind the aerial socket. He patched the liner and everything was good.

Sent through the ether by diddling with radio waves

Thanks all.
There’s no mould although in places the walls are damp to the touch and peeling wallpaper.
Dampmeter readings are high.
The damp course seems to be fine as the issue is only in the upper part of the house, not the ground floor.

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Originally Posted by eddie1

Thanks all.
There’s no mould although in places the walls are damp to the touch and peeling wallpaper.
Dampmeter readings are high.
The damp course seems to be fine as the issue is only in the upper part of the house, not the ground floor.

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As a stop gap a dehumidifier would help? We had issues on our outside wall for years and the side effects were drastically reduced with one.

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Originally Posted by eddie1

Thanks all.
There’s no mould although in places the walls are damp to the touch and peeling wallpaper.
Dampmeter readings are high.
The damp course seems to be fine as the issue is only in the upper part of the house, not the ground floor.

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It’s can’t be rising damp then.

Are you sure it’s not condensation? Which rooms is it?

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Are the chimneys still in use? If not, have they been capped properly with ventilation etc? Could be related to this had a similar issue in my last house

It’s in the loft extension and 1st Floor bedrooms only on the side wall that gets all the weather.
Chimneys are capped and have been visually checked;seem to be okay. The chimney stacks were rendered same time as the exterior wall

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Originally Posted by eddie1

It’s in the loft extension and 1st Floor bedrooms only on the side wall that gets all the weather.
Chimneys are capped and have been visually checked;seem to be okay. The chimney stacks were rendered same time as the exterior wall

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If it’s bedrooms could be condensation as we breath out a lot of moisture whilst we sleep.

Do you ventilate the rooms?

You say Edwardian. Does it have a cavity or is it solid walls?

It's got to be something to do with the loft extension. Is it a flat roof dorma? I'd be looking at roof and gutters on that first.

Solid walls
Rooms are well ventilated

Can you post a picture? Sounds like condensation or a leak from somewhere. Is the damp constant or does it appear when it rains?
Check for white filler or steel beading in the wall? These attracts condensation.
Wouldn’t use sealant until I’d found the cause.

Any photos? So many variables, could possibly be interstitial condensation? Where the atmospheric moisture reaches its dew-point the wrong side of the building fabric. Post some pictures and as much detail of construction as possible. I know we have many surveyors on here, I only have 29 years experience.

Could you seal the bricks?

Please find some photos in Flickr link below

Photos show wall before and after render applied to the wettest area of weather wall.
Interior damp patches in loft conversion
and state of chimneys & flashing and some of roof

https://flic.kr/s/aHBqjB5B8r

Very uniform/ specific patches of moisture in a diagonal line (wall ties?)- where does that correspond on the outer wall ?
Is the interior wall rendered - hard walled or dot and dab?
I’m thinking there is debris bridging the cavity maybe

Is there a closed-up fireplace? If so is there a vent where it used to be?

Looks like the room is getting too cold.

Is that frost in the pre-rendered photos at the tops of the gables?

Do you always get the damp after a down pour, or on cold days?

I suspect those damp patches are where the interior plasterboard lining has been adhered to the outside wall and warm, moist air inside has condensed on the resulting cold surface. Any problems it had as exposed brick will also potentially have been exacerbated by the external render. A building of that age would have ‘breathed’ and modern interventions cause the type of problem you see now.

The walls get noticeably damp after rainfall.
The house was built c1910 so not a cavity wall.
There are fireplaces in the bedrooms which have been closed and now have air vents.
The bedroom wall of the fireplace is also damp although not an exterior wall and chimney stacks are capped.
I do not know what the walls construction is under the plaster

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Originally Posted by funkstar

Looks like the room is getting too cold.

Is that frost in the pre-rendered photos at the tops of the gables?

Do you always get the damp after a down pour, or on cold days?

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I thought that was salts leeched out of the bricks/pointing?

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Originally Posted by blackal

I thought that was salts leeched out of the bricks/pointing?

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You don't see leeching in old properties.

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Originally Posted by eddie1

The walls get noticeably damp after rainfall.
The house was built c1910 so not a cavity wall.
There are fireplaces in the bedrooms which have been closed and now have air vents.
The bedroom wall of the fireplace is also damp although not an exterior wall and chimney stacks are capped.
I do not know what the walls construction is under the plaster

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I think JM is right. Cold surfaces have caused condensation. Biggest cause of damp in homes is typically cold walls and single glazed windows, hence bay windows are terrible for damp.

I'd suggest having the heating on max in that room for a good few days and see if damp persists.

Damp issue is there in summer after rainfall when ambient temperature high so not sure that it’s condensation

Damp aside I think that soil pipe needs a Durgo
Where is the damp/ room in relation to that outside wall

Can’t help with the damp issue directly but I’d highly recommend a PIV system to help with circulating air around your home

Does anyone know of any good company’s in Hertfordshire who would have a look at a similar problem and give advice?

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Originally Posted by eddie1

Damp issue is there in summer after rainfall when ambient temperature high so not sure that it’s condensation

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To me it sounds like a leak coming from somewhere especially if you are only noticing it after rainfall. You may need to get a roofer up there to check. Leaks can be notoriously hard to pinpoint.

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Originally Posted by eddie1

Damp issue is there in summer after rainfall when ambient temperature high so not sure that it’s condensation

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Then it can only be a leak

1910 houses may or may not be cavity wall. I'm not trying to tell you you're wrong, or that you don't know what you're talking about, but 1910 is in the period where date alone isn't definitive.

If it is cavity wall, then I'd look again at the roof. With tile over felt, you could have a broken or badly fitted tile. The water will go through, run down the felt and could be running down the inside of the cavity. From the inside of the loft you'd be blissfully unaware.

If it is a solid wall, then you need a membrane on the inside, battens and plasterboard. Or better waterproofing on the outside. Rendering (and painting?) should have fixed the issue. The only other thing I can think of is to fit some [-]god awful[/-] trendy exterior flastic cladding

I assume you've already checked the guttering...

Still not clear where this room is in relation to the chimney-
The 1st pic of the chimney close up is showing something under a room of tiles - it almost looks like it’s pointing upwards - this could catch water running down the roof and divert it under the tile - the flashing joint looks a little iffy too
https://live.staticflickr.com/65535/...ba3cf40e_c.jpgUntitled by biglewie, on Flickr

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Originally Posted by mikeveal

...then you need a membrane on the inside, battens and plasterboard. Or better waterproofing on the outside.

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Please don't do any of these suggestions.

Is anyone staying in the room?

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Originally Posted by funkstar

Please don't do any of these suggestions.

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Fair. It's a bodge.

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Originally Posted by mikeveal

Fair. It's a bodge.

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You’ll trap the moisture - op needs to find the source

That leadwork looks a right mess (imo). I reckon that'd be a good place to start.

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Originally Posted by lewie

You’ll trap the moisture - op needs to find the source

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Agreed.
Looking at those pictures the outside wall and chimney stack seems to be getting very wet. I don’t know why this is. Is the rain water then soaking through the render and the brick?

General guidance is to look for the cause to be able to find a solution. General defects that lead to moisture in buildings to look for

1 Understand what causes deterioration of building fabric including, for example, the
following:
• porous materials
• freeze and thaw cycles, wetting and drying cycles, soluble salts
• organic growth (including moulds)
• non-porous materials
• corrosion of metals
• timber: insect infestation and decay.
2 Understand the main mechanisms of dampness in buildings
3 Be able to recognise and identify evidence of infestations by the most commonly encountered wood-destroying insects, and take steps to determine whether the infestation is active.
4 Be able to identify the most common forms of wood-decaying fungi that affect buildings, and understand the conditions necessary for growth.
5 Understand how past interventions and consequential changes in the building could influence moisture accumulation in the fabric.
6 Understand why dampness may be manifest in a building
7 Understand sources of dampness, ventilation, heating and insulation positions/types and the impact these have on moisture levels.
8 Understand the reasons for surface mould and condensation in buildings.
9 Understand the significance of salts in assessing moisture problems, how salts can move through the building fabric and how this might influence a resistance meter. Understand how such salts can damage building materials.
10 Understand the potential effects of some impermeable wall and floor coverings.
11 Consider the influence of existing external ground levels, drainage, cold areas and ventilation.

I have similar issue's in my extension. As an ex roofer I understand capillary attraction which is a nightmare with free standing kerbs covered by lead or chimneys. My situation is being caused by us not heating the extension. Dehumidifiers are fantastic especially if you are using the radiators for drying? When I decorated I used rock wall insulation wall covering, it has heated the wall I struggle with up a hell of a lot. Our climate is very tricky to manage unless you have the heating on all the time.

Thanks again everyone for giving me some very helpful advice on this.

Those of you pointing to the Lead work being part of the Cause are on the right track.
I crawled up into the attic today and the chimney stack and wall directly underneath the photo showing the exterior chimney and lead work is dry but the area below the lead work ( hidden behind plasterboard in the loft extension)
is clearly wet so it would seem that the lead work is directing the water in and under the roof tiles.

So the starting point would seem to be to get a good roofer to come and replace that lead work/flashing.
Any other advice on what else should be done when the roofers here much appreciated.
if that is the only source of water ingress then hopefully replacing that will fix it and I wont need to go down the route of membranes etc.

That wall does get all the weather (as can be seen in the pics before rendering) and as it never gets full sun doesnt get much time in the year to dry out.

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Originally Posted by noTAGlove

We had damp in the corner of our house. Got somebody out who told me it was rising damp and £2k to fix it.

By luck I had left a large bucket in the side return which had filled up overnight. The bloody gutter had been leaking. Not enough to notice anything when it rained, but the bucket overfilling gave it away.

Persevere finding the root cause. It will usually be gutters, bridging or some other water ingress.

It is almost never rising damp and I am not sure that rising damp even exists anyway. Just a ruse to support a whole damp industry selling snake oil.

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Had a very similar issue on our previous house. Previous owners (in laws) had always had a damp problem in the kitchen which was converted from an old single brick stable adjacent to the house. They had tried to have it fixed by all the usual methods but it kept coming back. One night I saw the problem during a downpour. Rain cascading off the guttering, hitting a window sill and running down the wall.

The led work on the back of the chimney probably just needs sorting out and fitting flush -
Just looks unfinished - I can’t believe they the repointed that new led work into the stack and left the older led in that state

Is the stack still in use?
If not get it removed and tiled over, if it is could you not get it removed and have a single flue pipe instead, that way you’ll get rid of at least two culprits in one go.

I’d scaffold and knock everything off the list in one go.

looking at the internals there’ll be water ingress getting down the cavity until it hits something.

If it was near a gutter I’d say the roof membrane had failed where it meets the gutter and it was accessing the cavity from there but from your internal picture it looks too high for this.

90% of the time these issues are chimney/valley/ridge related rather than brickwork or pointing.


1) redo flaunching on top of stack
2) strip tiles around the stack
3) I’d hazard a guess it’s the soakers that are causing the problem either badly fitted or failed. New aluminium pre-formed ones are great.
4) redo flashings as has been pointed out.
5) check ridge tiles as possible it’s coming in there and working it’s way down a rafter.

Did you get is sorted?