Is This Condensation or Rising Damp?

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Roger tries to figure out another damp issue, or does he?
Here's our message from Jordan:
We moved into this property about 5 weeks ago and have noticed that after the bad spell of rain, the wall has a big wet patch with mould appearing.
We had a survey done before we moved in (the dampness wasn’t present then), highlighting the damp but putting it down to condensation damp.
Since moving in, we have had 4 damp specialists around who have since quoted us for different bits of work but have all said it’s down to different things.
This is our first house, and we don’t know what to get carried out as some of the treatments were costly. Can you help identify what it actually is? Rising damp or condensation damp etc.
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#risingdamp #diy #homeimprovement
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[@jannenreuben7398]

There's a lot of things going on here as usual but I'd wager the root cause is simply condensation - warm moist air from the room hits a cold spot in the lower corner of the wall and condenses. Damp wall surface then provides nice conditions for mould to grow. To make it worse, the damp wall is prevented from drying out by inappropriate use of modern materials. Looks like somebody has tried to fix it in the past with an air vent into the cavity but this is probably just keeping it cold. Solutions inside - better ventilation of room, remove wallpaper and paint using clay paint or other natural breathable paint. Keep an eye on internal humidity levels and temperature. Check under the floor if possible and make sure any void is clear and well ventilated. Remove laminate flooring and membrane (if fitted) so floor can breathe. External - remove cement pointing and repoint in hotlime where necessary. Check cavity is clear of debris. Check drains / galleys/ gutters etc. are working properly and not blocked. General - Be wary of damp companies. Most of them are complete monkeys who will wreck your house with useless tanking and injections. Spend your money instead on a copy of "The Warm Dry House" by Peter Ward which will help you understand what is really going on with damp.

[@jannenreuben7398]

@@criollitoification 1) There'd be little benefit pointing in lime if the house was originally built with cement. In the UK there's a good chance that anything pre-war was done in lime but it fell out of favour afterwards. 2) Condensation and cold bridging are 2 sides of the same coin. Really you need to calculate the dew point of the wall (the point at which water vapour condenses into liquid form) which you can do either with a special dew point thermometer or measure the air temperature and humidity separately and use an online tool. If the wall ever falls under that temperature you will get condensation. Window reveals can be cold anyway and DG windows don't allow much ventilation at all when closed. This is why I retained my original sash windows because any moisture condenses on the glass where I can vac it off, rather than it going into the walls.

[@kingofwebguru]

Hi @jannenreuben7398, please could you provide a link to "The Warm Dry House" by Peter Ward. There are two PW in KZbin.

[@thesunreport]

I'm guessing it could be both problems. There are obvious condensation drips coming down the walls, but the internal mould goes up higher than I think a localised condensation problem would go. Looking at the pointing around that front corner I think there might be water ingress/entrapment, especially with the wind, and there must be enough water to keep the moss alive. I would definitely get the pointing done (properly) especially around that front corner/edge where it meets that other wall, get all of the moss out and do the pointing on those lower sets of bricks as well. After all the condensation could be coming up through the wall and out of a crack under the windowsill or something rather than simply moist air from the house. That's my guess anyway.

[@old486whizz]

I agree, too few pictures.. seems to be in the corner/rising, so could be from the rendered wall, from higher up, from the front, from a blocked drain, etc..

[@leeberry9666]

Hi Roger, the pointing does look a bit ropey but I don't think that is the problem. That is a condensation problem which can easily be overcome. Well done for your diagnosis.

[@user-mn9qu1gd2m]

That outside corner seems to be very green and has a lot of moss as those the gutters been leaking and splashing back on that corner making it wet and a cold spot , I’d check that when it rains first then maybe paint that corner with storm dry , it has had a chemical damp course at some point can see drill holes that have been repointed

[@ambrosiad1588]

dam you got there before me, but yes theres a lot of wetting on the base of the wall and green around the air vent, the gutter above is pants, waters is pouring down the wall splashing, possibly water ingress through the subfloor air vent

[@dovedaledampcureserviceslt2248]

You can even see the drips that have formed and run down the wall.

[@davidhill431]

That's probably cleaner

[@Richie-C]

Absolutely agree, it’s running down the wall

[@sergiofernandez3725]

Pull out the air brick. Have a look inside the wall. Could be full of rubble or wet rock wool. See what internal ventilation there is if any

[@telstar4772]

House is too old for Rockwool but def knock out the airbrick

[@lightx500]

You are right could be those cavity wall fillers retro fitted as well

[@alanyoung7532]

Indeed - the first thing to check in the case of cavity walls is the effectiveness of the cavity and DPC arrangement - especially if its not the "condensation season" and the building fabric has been warm for months.

[@alanyoung7532]

Rockwool (or something even worse) could have been injected in modern times as is most often the case.

[@Humanity101-zp4sq]

rockwool will drain and dry by gravity. Glass wool will retain moisture. Possibly blown glass wool in the cavity? Look for mortared holes where it was blown in.

[@gregwood8141]

I actually had a very similar problem. In my case plasterboard had been incorrectly dot and dabbed to the solid wall as there wasn't a continuous line at the perimeter of each board. As a result cold air could come through the below floor air brick, which was in a similar position to that shown here and creep up the gap behind the plasterboard. The cold then led to condensation. As soon as I put PIR between the joists, the problem went away. I suspect a similar issue is happening here, although if as Roger says, this is a cavity wall, air would be coming up the cavity rather than behind the plasterboard and could be fixed with the installation of an airbrick sleeve.

[@markmcgrath4853]

looks like a cold area by the airbrick causing mould a low level ! also bridging damp coming from the external rendered wall !

[@johnmusgrave3179]

The airbrick will keep the caviy cold which in turn will cool the inner leaf of the wall. All you need then is moist warm air in contact with the cold spot and condensation is inevitable.

[@dociledeer3818]

When I was inspecting houses in response to a dampness complaint I found that (generally) black mould and only black mould is condensation, some black mould with yellow staining was structural/penetrating dampness. Best way to find out is to dig a wee hole in the plaster and get the protimeter on to the brick, if the brick is dry then it’s condensation. Thank god I’m not doing that anymore. 😊

[@KendalSmithy]

The dribble marks down the wall indicate condensation. Plus the cavity may be full of rubble which could let some moisture through but it would also reduce the insulating qualities of the cavity and make the inside wall colder than it should be.

[@manfromdelmonty303]

This

[@sharonclaridge]

Looks like the wall in our porch before we started to leave the window open - all fine now. Well actually it's bollock freezing out there with the window open but it's too small to have the dehumidifier out there so although it's cold, it's dry cold and doesn't smell fusty.

[@keithwebb658]

A fair amount of moss on ground close to the wall suggests a north facing wall so it's never going to feel the heat of the sun and will always seem cold. Poor movement of air inside will add to the problem. That's condensation.

[@alanyoung7532]

Came across a similar problem to this a couple of years ago after a so called “specialist” had jumped to the conclusion the affected wall needed 10k worth of rising damp treatment. In that case it turned out to be an obstructed cavity transferring moisture to the internal leaf. This then became cold as the dampness reduced its thermal performance, which in turn resulted in surface condensation as a secondary source of damp. My approach would be initially (especially in winter) to monitor internal Relative Humidity to establish is this is persistently high (normal is usually between 40 & 60%). If so, or if the house is poorly ventilated, anti-condensation measures (extractors & trickle vents) are probably needed. I would also take a few initial surface readings to check if the wall surface is near dew point. The green paving externally may also suggest that rainwater spillage is taking place in this area. With cavity walls, the outer leaf should be separated from the inner leaf by an effective cavity, which acts as a barrier. DPCs/DPMs also form barriers to internal damp transfer. Therefore, if dampness is present to the inner building fabric of a cavity wall it is probable that either: 1) The cavity is incorrectly formed or, more likely, compromised, and/or 2) The DPC/DPM arrangement is incorrectly installed and/or compromised. It follows that, in the case of cavity walls, it is necessary to verify the efficacy of these barriers during the early stages of an investigation for internal dampness.

[@markmcqueen8741]

I've had similar problem for the last few years, and i recently had the company who injected the cavity with insulation 19 years ago , come out to investigate and after drilling holes for a small camera they found that the insulation had dropped and was causing moisture to transfer to the inside walls. So now they are going to have to extract all the insulation from the cavities and make good internal damage and re insulate. And reinstate a 25 year guarantee.

[@MrAas41]

Hi, I think this may be the cause in our house. How much did it cost to get it fixed?

[@Humanity101-zp4sq]

Cold wall, probably north facing. Dew point reached on wall surface due to habitation water vapour. Needs a hygrometer and a dessicant dehumidifier, or more heat in the room and trickle vents in the window. Injected DPC one course above vent (filled drill holes visible).

[@mark5282]

Check the humidity with a constant monitor . Monitor the surface temperature and the internal temperature, if the surface is below the dew point condensation is inevitable.

[@nikdoznamej7698]

i would use a laser thermometer or thermal camera and check out if the wall isnt much colder then the rest on some cold days. actually I had a cold spot (corner) in a block of flats on the second floor. in winter the corner gets to 5celsius when freezing outside. rest of walls are about 15celsius and of course thats the place where there will be condensation happening

[@michaelchapman4269]

Would love to get that brick out above the air brick, looks very wet, wonder if cavity is full up with mortars etc and transferring damp from that rendered wall. But you can clearly see condensation has run down the wall.

[@MarvinofMars]

Roger, I have came upon a problem like this with new build turn key houses I was the building as a site manager. With new screeded floors on ground level the sand and cement screed was 100m thick. Upon this green screed was S1 tiling adhesive, ( S1 is a green screed adhesive) yes the L_ _ _ _n product was a great product but it simply pushed the the moisture to the cavity walls causing rising damp. It did stop after a few months, get a Thermal camera to spot the coldest spot.

[@beijingbond]

Bang on, Roger. I had a terrace house that was built around 1844. My neighbour asked me to look at his house as it was black behind his wardrobe and curtains. I asked him if he ever opened the windows. His answer: "Nope". He wiped the mould off and made sure he had a window open when he showered and cooked. Problem solved.

[@SilverTrowel631]

That looks like condensation to me. But just a point of order .... That red dyed pointing is actually the original pointing or at least it is very old. It's failing, falling out and exposing the lime mortar behind. I believe they used that red mortar for the 'Housing' when tuck pointing, I think it was also used when doing a 'Penny Roll' finish. I have from time to time come across it where it was used in a standard struck pointing finish. Whatever the truth, it could do with re-pointing.

[@burwoodbuild]

I’d agree it looks like condensation from the pictures shown, trapped moisture tends to settle in corners and behind wardrobes. In this case it gets higher up the wall as it gets closer to the corner behind the door. Could firstly try fitting some window vents to the double glazing?? 🤔

[@Luckianmet83]

I do not see other mention the fact that also the reason why that part of the wall is colder. So a cold wall will attract condensation when the humidity is high. So that also needs to be addressed by fixig the insulation on the outside, or maybe there is no insulation and one needs to be added.

[@maheshpandya2466]

Hi Roger - Poor ventilation leading to condensation

[@linuxforpunks]

It's in a low corner and on an exterior wall. Nothing up with the woodwork (yet) so I'd bet on condensation too. The exterior problems might just be making the inside wall colder.

[@daman4802]

Been a really cold winter. The cold weather has made the wall colder and it will attract more moisture out of the air than in a mild winter. Condensation.

[@TheDoosh79]

I agree definitely condensation. Could it be where the cold air comes in when the door is opened and closed and it hits the warm wall?

[@nin3755]

I have moved into a rented place with very bad black mould from having been left unoccupied and unheated for 6 years. For 2 days now I have been bagging up all the absorbent materials, washing the windows woodwork doors, next to pull up carpets and remove them. There are cavities around the doors windows and under the flooring in the kitchenette area and the shower area. I have stripped the wallpaper off in the bedroom and found black mould on the back of it and the wall behind. From this video I think after removing carpets the next thing is a dehumidifier and continue washing down the walls. Is there anything I should do before plastering? Would a pva or sealant be good on the walls? Should I bleach or use a mould treatment on the black that is on the stone wall? Or plaster over it?

[@james83777]

Looks exactly like condensation. Wonder if the owner has it in upstairs rooms on the side wall too. Ventilate and get that humidity down below 60%. Not easy with old houses. If it’s going to be decorated at some point internal insulation. Or even better external insulation and render or clad.

[@bluzrokluvr]

A common problem in cold entrance halls. Obvious external maintenance issues need attention to ensure the wall is made weather-tight, but internal wall damage indicates seasonal domestic condensation, the mould accumulation on the wall surface suggests the entrance hall is colder than the rest of the house. Improved heating and ventilation, a dehumidifier, maybe even ultimately a PIV (Positive Input Ventilator) - if the damp airborne moisture is migrating from warmer areas of the house, with the usual domestic suspects at the root, indoor laundry drying, cooking etc etc. The symptoms can be cleaned with a supermarket mould remover, consideration should also be given to applying an anti condensation coating to the plaster surface by brush or roller, as supplied by Wykamol, Safeguard and others. Beware though the mould may return in cold weather if the cause i.e domestic 'lifestyle' condensation, is not sorted out.

[@SurreyAlan]

I never had this problem until I married (again) at which time I started to find mould behind bedside units. A really good clean with anti mould spray seems to have stopped it.

[@sasa1982uk]

Look at all that moss, could it be in the shade most of the day so it's cold, cold bridges to the internal wall, meets the warm air when the heating is on, boom condensation. I think Mr bisby has nailed it. Not just a good Hilti sales rep.

[@JT-si6bl]

Plenty openings and moisture accumulating for ingress... just look at any hole size and add it to the other hole, size it all up - there's quite a big hole. Take out an inch of mortar and fill it up with 'lime mortar' which is sharp sand and NHL 3.5 Lime 3:1, and packed in there tight. Cement will kill the old mortar and eventually the brickwork. 4:14 time stamp - You have a green stone at the base of the 'render' (i think its natural stone) that is 101 moisture hotspot, like there will be moss in there and roots for a trifid or something... right next to the two weak points next to the air brick. Very easy water ingress point there. Get that mould cleaned off.

[@dovedaledampcureserviceslt2248]

Looks like condensation to me Roger, Classic case!

[@willdeit6057]

looking at the wall's repointing I would assume this has been an ongoing problem. As it appears there is no damp course I would also think that there is no cavity tray fitted, if the bricks are not waterproof it's possible that the water is getting through the bricks higher up and running down the inside, seen this before but it was a guttering leak on the house side of the guttering and the water just ran down the wall, there was no insulation in the wall and the window lintels transferred the water into the inner wall.

[@lazylad8544]

Absolutely get yourself a dehumidifier. Rodger is spot on with his advice.

[@Jim_Manlove]

I don't think he is, but obviously a dehumidifier will help.

[@lazylad8544]

Doesn't matter what you think. Those in the know. Know.

[@Jim_Manlove]

@@lazylad8544 This literally my job. I'm one of those "in the know".

[@CulturalArchitect]

A simple in-room thermometer with humidity gauge would be a quick and easy way to understand what the levels are like in that space versus the rest of the house. Follow that up with the suggested dehumidifier.

[@ghengis430]

How long do you run the dehumidifier for? How often? The damp in mine is in bottom corners of North facing walls. It's been very cold inside as well. Recently had more airbricks with a good clean, but on the east wall, as that's where its a bit mossy.

[@CulturalArchitect]

@ghengis430 some models of dehumidifier will have an auto-run function meaning it'll shut off when it detects the air is dry enough. Others have suggested timed programmes, which you gradually reduce as the room dries out. In any case, you'll probably find it's running for a while to start with while it does it's job. If the damp starts to dissipate and stays that way, then just some light running is all you'll need. They don't consume huge amounts of power - in fact, some households favour them over tumble driers to dry laundry, as a more cost-effective method!

[@ghengis430]

@@CulturalArchitect thanks.

[@davejohnston5158]

Check type of wall. Cavity, stone, solid brick, no-fines concrete etc. 1. Take a brick out at dpc level. 2. Check if external yard is above floor/internal dpc level. 3. Take the skirting off and see if the internal dpc is bridged by wall plaster. Superficially it looks like black spot/ condensation and could have had a piece of furniture covering it which would have kept the wall cold and at dewpoint causing surface condensation but bridging of the cavity could also be a complicating factor.

[@peepiepo]

The lines running down make it look like condensation certainly

[@anthonywilson8998]

There is an air vent allowing cold air into the cavity so the inside leaf is very cold. No need for an air brick in cavity wall reducing thermal insulation to only the inner leaf. Take out air brick and replace with solid. Then you are back to a sealed cavity wall with some insulation from the cavity. B Arch RIBA retired.

[@Stan_55UK]

Judging by the house I am working on, and no other experience whatsoever, my house had similar mould above the skirtings in a corner. This was caused by a cold spot, which in turn was caused by a leaking downspout (long story.) In my experience, where there was mould, it appeared to be condensation. In another part of the building there is a bit of rising damp (bridged damp course) and there is damp/salt on the wall, but no sign of mould (I wonder if the salt kills mould ?) I expect that every house is different.

[@mikeyc1348]

I think it's condensation. Be worth getting a humidity meter so they can see if above 70%. Probably worth improving ventilation with an airbrick.

[@RAM-yn1nn]

Condensation. Look at internal use, hanging washing indoors will create very high humidity and recommend a good dehumidifier. Also apply a mould resistant paint..

[@normanboyes4983]

Judging by the moss outside -it is North facing and perpetually wet and likely gutters are full of crap, joints leaking.

[@groundhogday37]

Iv got a question about having a built in wardrobe across outside wall floor to ceiling in bedtime there's a fire place need blocking of ,if I vent the old fire place will it cause mould behind the wardrobe, also do I need to insulate behind wardrobe as there's going to be a gap of about 30mill cheers Steve

[@alliedfroth]

I have same issue & its condensation when I put the heating on & the wall is very cold. I bought a dehumidifier & it sorted it.

[@websurfer1585]

We have similar issue in one or two rooms, and i have noticed tbat our dpc is ABOVE the airbricks AND the dpc is covered over with cement to try to hide it, i wonder if the latter could cause wet bridging?

[@TheOriginalDaveJ]

Look at all the perps and beds that haven't been filled, that joint between render and brickwork looks proper ropey and the attempt at repointing all leave a lot to be desired. Rake out and repoint the brickwork and cut out that ropey vertical joint, should make life a bit easier.

[@JohnSmith-yx1cj]

Hi Rodger I have a similar problem in my brother’s bungalow It’s in both corners of his bedroom, I have washed it off as it’s either side of a double glazed window he never has the window open so I told him to open it daily so we can monitor it hopefully this will sort it if it’s condensation 👍 Ps great channel 👍

[@brianhewitt8618]

the ground clearance to that airbrick looked suspect, water could be creeping across that, if its behind the damp that is

[@jackkruese4258]

Would you recommend Storm Dry if it was wasn’t condensation ?

[@catabaticanabatic3800]

Water is tracking down the walls by the look of it. It seems to be condensation and a severe lack od air circulation. Black mould only thrives in areas of poor ventilation.

[@madintheheid]

I'm with Roger: in the absence of the full picture... almost certainly the cavity wall is bridged with mortar and debris from the construction days. Get a small-ish hole cutter and go right through the outer wall to expose the gap, or lack thereof. If you cant then clean it out because the cavity doesn't seem to exist, then keep on coring and then screen with a ventilator and bug screen .

[@SierraNovemberKilo]

Has the cavity been filled with so-called "insulation"? Is the cavity actually blocked with rubble/rain soaked matter? It seems to me a draught is coming around that door, and is meeting warm moist air right there on a cold wall.

[@peterdorr6190]

Glad the the brick does appear if some thermal bridging going on?

[@darkseas3846]

Would love your opinion on the issue I have in my home that is a high town property that is only 6 years old

[@slyteen2197]

It's penetrating damp and condensation. Look low level to the right hand side. Poorly pointed and green with algae growth. Source of the penetrating damp could be outside ground level and/or a roof issue.

[@tikaanipippin]

It is a corner, and you can see the mould rising towards the corner. The condensation has dripped down causing runs from even higher. This is typical of stagnant air in a cold corner. In my opinion, dehumidifiers do nothing to move stagnant air around to dry out cold corners or cold damp air falling down under windows, and are an expensive and inefficient alternative to a simple 30watt desk fan aimed at the area where the condensation is present during the period of October to April, when we tend to have the central heating radiators on. Moving room air around allows condensation to evaporate and the wall to warm up to the ambient temperature of the air in the room. If there is no cold surface, condensation will not occur. So we do not attempt to remove the humidity, but we prevent cold surfaces for condensation to form upon. You can prove this with a fan aimed at a window where condensation regularly occurs. It is similar to the situation where car windows mist up. You don't open the windows, you move air over the windows so they are uniformly warm with the interior air, still containing as much moisture as before.

[@alanyoung7532]

Not sure what time of year the damp is showing itself but if its out of the condensation season (eg August) then its probably not just condensation at work. With cavity walls it is almost always prudent to check the effectiveness of the cavities and DPC arrangement at an early stage in an investigation. One needs two open eyes and an open mind as Dr Robyn Pender advises.

[@XxiTziCHRiiSzx]

Hi , I have an interior wall that has bad peeling paint there's no mould at all the bottom of the wall is more hollow and the top is solid ,I'm ready confused I'm selling my house so I'm trying to sort the issue out my self any ideas .Thanks Claire

[@arthurwoodward9980]

Needs to try a Dehumidifier in my opinion, I use one in the winter which collects about quarter litre of water a day. Good luck.😊

[@leonskum.5682]

Are they expensive to run?

[@Mitch-Hendren]

Leon i run one in winter , its about the same as a fridge.

[@jannenreuben7398]

They're fine if you've got localised dampness that needs a quick boost to help it dry but they don't solve the root issue. In some cases they make it worse because they can dry out a wall surface faster than the moisture comes in which can lead you to an apparently dry wall which is still soaking wet inside.

[@fiskrond9212]

The amount of moss on brickwork and algae on stones.. something ain't right. Usually an indicator of a ~North~ facing wall. Has there been something built/planted that affects the airflow (mebe also sunlight?) around this part of the property?

[@thegogetter8557]

Hi Roger, Are there any key ways of identifying damp from Condensation. For example Can Damp reach higher up walls?

[@gray3553]

Cold wall possible north facing, Hang Wallrock Thermal Liner it will warm the internal surface and reduce heat loss thus illuminating condensation. Look into it worth a try.

[@cliveb3917]

I don’t think I’ve seen anyone recommend a PIV - positive input ventilation - unit. I’m just a DIYer, but I’ve installed 2 of these into 2 of my sons’ properties, and they made a significant improvement overnight, and things just got better from there. Better than a dehumidifier. Might be worth doing a video on PIV installation?

[@bigtel1977]

I was gonna suggest the same thing…PIV unit, I fitted one to a rental house that’s a solid 9” wall due to condensation etc…within 2 wks it was gone….I’m gonna for one in my own place now..

[@gypsygem9395]

Interesting, I hadn't heard of those before

[@295walk]

Apart the external issues, A lack of ventilation with a cold /wet wall ?

[@johnwilkins5850]

Same in my room, washed it down with bleach/water dried it off, bought a dehumidifire end of condesation.

[@Matrixresin]

They love a rising damp q&a here 👍👍

[@plumpii7177]

Cold spot, moisture in the house.. clean it, paint it, run a dehumidifier frequently and it won't comr back... probably... bogs, baths, showers, cookers, steam from dishwashers, damp clothing, sweat, it's all gotta go somewhere..

[@glenr901]

I agree it's condensation, however it appears to me this is not a cavity wall but a solid, 9inch wall construction, with dpc formed by blue engineering brick. The photos don't have enough context to see the surrounding situation but it may be likely the wall is getting saturated and cooling allowing warm moist air to condense internally.

[@over-engineered]

Condensation, heat it, ventilate it, or even better get a dehumidifier. I had same issue at home.

[@paulbrook2459]

Looks like condensation ? It’s hard to tell without more pictures 👍

[@billysmart24830732]

If you cannot diagnose the problem, what about looking for the issues that would cause the problem and then that answers the question i.e. what other things would you see if it was condensation?

[@alanyoung7532]

Elimination is a good approach Not sure what time of year the damp is showing itself but if its out of the condensation season (eg August) then its probably not just condensation at work. With cavity walls it is almost always prudent to check the effectiveness of the cavities and DPC arrangement at an early stage in an investigation. One needs two open eyes and an open mind as Dr Robyn Pender advises.

[@johnnymetalcore5608]

100% agree Rog

[@c9off]

In addition to all suggestions, would cleaning the wall not help a bit?!

[@Moultonist]

Is that a chimney breast with damp? Rainwater getting in from above? Roger says it's a cavity wall, presumably because of the stretcher bond, but it looks like an old Victorian house with back yard and privy, cobbled street, stone quoins. I wouldn't expect a cavity wall construction. Could it be a rare example of a single skin of brickwork at 4"?

[@greatdelusion7654]

If this was a serious rising damp situation, I would expect to visually see more flaking of the plaster and also some sort of deterioration or rotting to the woodwork (skirting). This looks like condensation to me.

[@andreoproprio]

Basically condensation, triggered by extra cold and thermal bridge because of the air vent. Definitely ventilation and dehumidification are the only solutions.

[@RobNorman08]

I have to agree with Roger, condensation would be my opinion, it would be wholly unlikely that the flank wall built both with cavity and of semi-engineers (something like south waters) would be letting any damp through, it would take an awful lot of constant direct water exposure to even begin to affect that type of construction, flank walls don't tend to get a lot of weathering. I guess apart from using a de-humidifier the only other option would be to strip the skirtings and plasterwork back and have a look at at the wall itself, to see if there is any sign of damp.

[@highpath4776]

That laminated ? floor covering also looks to be covering up other things, with airbricks there is ventilation down through ill-fitting traditional floorboards which now is not happening.

[@TryDiy]

No air brick inside which probably was blocked up because it's "letting in the cold" hence condensation.

[@johnf3326]

Streaks running down wall indicates condensation as does black spotty surface mould rather than staining. I'll bet the cavity is full of crap at the lower levels

[@grahammitchell6435]

Has the rest of the house been super insulated and shut off from air circulation? Has this wall got any form of cavity insulation? In my opinion the warm damp air circulating in the house has found a cold wall to condense on and i feel this wall needs to have some sort of insulation to warm it,perhaps a frame with celotex then plasterboard ,or maybe insulated plasterboard to warm the wall.A warm wall cannot get condensation!

[@alanyoung7532]

Not sure what time of year the damp is showing itself but if its out of the condensation season (eg August) then its probably not just condensation at work. With cavity walls it is almost always prudent to check the effectiveness of the cavities and DPC arrangement at an early stage in an investigation. One needs two open eyes and an open mind as Dr Robyn Pender advises.

[@SA-vz7qi]

There is a lot of moss on the floor at the bottom of the wall.

[@stequality]

Im looking at the comments some say condensation and some say damp.... so which is it ?

[@jamesodd3896]

I’ve used some insulating paint in some corners in my lounge and it has vastly reduced the condensation . Just a little tin and in the problem corners 2 layers .

[@aklouslibby563]

Hi there just wondering if you could kindly send me the name and details of the installation paint you used in the corner of your living room as I would be so grateful yours Alex klous Libby, Co Tipperary lreland 🇮🇪

[@jamesodd3896]

Yes the one I used was Ronseal ACPWM750 750 ml Anti-Condensation Matt Finish Paint - White. It was called insulation paint when I bought mine. It now mentions insulating in the tech details .

[@aklouslibby563]

@@jamesodd3896 ó my friend James thank you very much for sending me the name and the details of the paint you used on your walls I be going into Tipperary town this afternoon and get myself a tin ok James my friend you'll be having yourself a good new year all the best Alex

[@alangknowles]

That external wall doesn't look like a cavity wall to me. It's a 9 inch solid wall. And you pointed out lime mortar and engineering bricks. That's for 9 inch Victorian. Even the skirting board reflects that age

[@Sjf542]

The brick pattern would be English or Flemish bond if it was a solid wall. It's stretcher bond so it'll be a cavity wall.

[@sugarpuff2978]

I would start by getting a moisture metre and see what it picks up in that room.

[@MrDazTroyer]

If its just condensation and lack of ventilation, Kilrock is amazing at killing the mould.

[@bothdenis1]

draft from the lower part of the door and or frame!

[@ktb9369]

Has anybody ever had a problem with freezing cold skirting boards even in summer. My ground floor flat is like a freezer even with heating on. Dehumidifier takes 5 litres water a day. North facing long wall 26ft. Floor is freezing concrete with asphalt screed. Even ceiling is a freezer believe it's concrete.

[@paultant6741]

Would say condensation. Looks like with the algae that wall doesn't get too much sunshine and will be cold

[@v8motors.]

Poor pictures results in pure guesswork!

[@davidwood62]

You could place a simple glass against the inside face of the wall. Leave it overnight. If damp is found on the inside of the glass, then damp is coming through the wall. However, if the damp is on the outside... then it is condensation.

[@SkillBuilder]

I have done this by sticking squares of cooking foil on the wall. If you get droplets on the room side you know it is condensation. The trick with the glass works but you need to dry the wall thoroughly because moisture will have condensed on it.

[@agt155]

Something's not right with that door frame. Looks like a new door has been fitted further outward than the existing one and the difference made up with a bit of trim hence the skirting gap. My bet would be the problem exists behind that trim.

[@mikewalker8655]

We need way more photos, otherwise it's just guess work

[@peterthebricky]

To the right of the air brick looks like a bit of subsidence . Looks like front corner of the house dodgie downpipe perhaps

[@brianhewitt8618]

or to much cold air getting into the cavity, through/maybe a cracked air brick

[@dread4836]

De-humidifier x 5 Hours per day to reduce humidity, clean thoroughly and force dry and then seal with breathable paint

[@SkillBuilder]

I would say not to force dry. It dries the surface and stops the moisture chain. If you let it evaporate slowly it will pull the moisture out.

[@niks966]

I have this kind of damp and the plaster crumbles...it is rising damp.