Condensation on interior walls is a common issue caused by warm, moist air coming into contact with cold surfaces. This can lead to mold and mildew growth, asthma, allergic reactions, and even cancer. Moisture on walls can be caused by trapped moisture or water seeping in, leading to condensation, leaks, and poor drainage.
Damp problems in a house can be caused by various factors, such as rain getting through the walls or roof, moisture being absorbed from the ground, condensation settling on cold surfaces, and poor ventilation. To reduce condensation on interior walls, it is essential to use fans to improve air circulation, maintain consistent temperature throughout the home, and avoid moisture accumulation.
There are four common ways walls get wet: bulk water leaking into the wall, exterior rain or snow events, or an interior water leak from plumbing. Condensation occurs when there is a large temperature difference between the inside and outside of the home, often caused by trapped moisture or water seeping in. Cold air gets through siding, sheathing, and fiberglass, which then transfers through to the drywall and meets warm interior air.
Condensation occurs when humid air accumulates inside a home, often due to poor ventilation. Solutions include ensuring proper ventilation systems, adjusting the humidity level in your home, and using a humidifier turned to high.
In summary, condensation on interior walls can be caused by various factors, including excess moisture, poor ventilation, excessive humidity, and structural issues. To ensure a dry, moisture-free home, it is crucial to address these issues and maintain a consistent temperature throughout the home.
📹 Tell the difference between condensation and damp in 1 minute
This is a really quick and easy way to tell the difference between condensation and damp with no equipment needed.
Why is moisture coming in through my walls?
Damp patches on walls or ceilings after a rainstorm indicate leaks, requiring immediate attention. Inadequate roof insulation, ventilation, or gutter systems can cause ice dams in winter, especially after heavy snowfall. Snow accumulates on the roof, but lacks insulation or ventilation in the attic, causing it to melt from the heat inside the house. This ice forms an obstruction in the gutters, which is then forced downward by gravity, freezing them until they detach from the home.
How to stop moisture from coming through walls?
Damp and mould are fungal growths caused by excess moisture on the inside of a property, often coupled with damp walls. The source of moisture can be internal or external. Common causes of damp and mould include rising damp, which is caused by moisture from the ground that travels up through the walls of a property by capillary action, and penetration damp, which is caused by an external source of moisture through an external wall. Wet exterior walls and damage to brickwork can also be signs of penetration damp.
Condensation can be caused by a lack of ventilation, especially in winter when people close their windows and have their heating on. Water leaks can also cause isolated patches of mould on ceilings, especially near chimney breasts that can be prone to leaks. To prevent condensation, it is essential to improve ventilation in your house, avoid overusing tumble dryers, use extractor fans, and open windows to maintain regular airflow.
How do you treat moisture in walls?
Damp on external walls can be a significant issue for homeowners, causing visual discomfort and potential health risks. To address this, repair masonry defects like cracks in walls, apply a suitable render, remove excess moss and leaves from roofs and gutters, improve property heating, and insulate cold walls. Different types of dampness exist, and the treatment method varies. Internal damp patches can cause mould, which can affect asthma and allergies sufferers. Cold damp walls can also make rooms feel colder and more uncomfortable to occupy. Addressing damp walls is crucial to prevent health issues and ensure a comfortable living environment.
How do you reduce wetness in walls?
Proper ventilation is crucial in maintaining moisture-prone areas of your home, such as kitchens and bathrooms. Open windows or use exhaust fans to prevent moisture buildup and condensation on walls. Walls are structural elements that define and protect spaces, but they can be affected by dampness, which can indicate issues like excessive humidity, water damage, or foundation problems. Identifying and addressing the underlying cause is essential to prevent further damage and ensure the safety and structural integrity of your home. Wall dampness is common, especially during the monsoon season, and if not addressed properly, it can lead to issues like leaks, peeling paint, cracks, and health issues due to mold and fungi growth.
How do you fix a wet interior wall?
In order to repair damp internal walls, it is first necessary to identify the underlying cause and implement a solution before proceeding. It is recommended that a dehumidifier be purchased or hired to facilitate the drying of the room. The use of a stain blocker is advised to prevent future staining. Replastering of walls should be undertaken, and the walls may then be decorated with paint, tiles, or wallpaper.
How do you remove moisture from inside walls?
To dry wet walls after water damage, use fans and dehumidifiers to remove moisture from the air and walls. Professionals use tools like moisture meters, infrared imaging devices, dehumidifiers, and heavy-duty fans to ensure the walls are truly dry before further repairs, painting, or refinishing. Quick drying reduces the risk of structural damage and prevents mold growth. Water saturates drywall, which is an absorbent material with gypsum and cardboard-like paper on both sides.
The extent of this movement depends on the wall’s construction, water amount, and water height on the wall material. Drywall can wick water up to 30 inches, with higher levels on the inside due to restricted evaporation. Water damage may be visible or not show signs of moisture at other times. It is essential to call a restoration company immediately to ensure the walls are dry before further repairs, painting, or refinishing.
How do I stop condensation on the inside of my walls?
It is recommended that internal walls be insulated in order to prevent condensation. This can be achieved by creating a thermal barrier between the warm air and the cold wall surfaces. The use of draught excluders can effectively seal gaps around doors and windows, thereby preventing the infiltration of cold air into the home and the subsequent condensation formation on internal wall surfaces. Both methods have the potential to enhance the comfort of the living environment.
How do you stop moisture from coming through walls?
Damp and mould are fungal growths caused by excess moisture on the inside of a property, often coupled with damp walls. The source of moisture can be internal or external. Common causes of damp and mould include rising damp, which is caused by moisture from the ground that travels up through the walls of a property by capillary action, and penetration damp, which is caused by an external source of moisture through an external wall. Wet exterior walls and damage to brickwork can also be signs of penetration damp.
Condensation can be caused by a lack of ventilation, especially in winter when people close their windows and have their heating on. Water leaks can also cause isolated patches of mould on ceilings, especially near chimney breasts that can be prone to leaks. To prevent condensation, it is essential to improve ventilation in your house, avoid overusing tumble dryers, use extractor fans, and open windows to maintain regular airflow.
Should you wipe condensation off walls?
In extreme cases, using a dehumidifier, regularly wiping down surfaces affected by condensation, and using disinfectant or fungicidal wash can help prevent mould growth. Mold-inhibiting paints and sprays can also reduce condensation effects. Check all accessible plumbing for leaks, guttering and down pipes for cracks, overflows and waste pipes under sinks for leaks, roof leaks, damaged outside walls, and high garden or path levels overlapping the damp proof course.
Why are my walls wet inside my house?
Condensation on walls occurs when hot humid air cannot escape through traditional ventilation and settles as moisture on cold surfaces like windows and walls. It is common in kitchens and bathrooms, especially in autumn and winter when people stop opening their windows. Condensation can also be identified by tide marks, rotting or decaying timber along affected walls, and white salt residue. Moisture rising from below the ground level into masonry walls can be identified by a distinctive tide mark stain. As moisture absorbed from the ground penetrates the brickwork, wallpaper and plaster can become damaged, and white salt deposits can appear.
📹 Is This Condensation or Rising Damp?
Roger tries to figure out another damp issue, or does he? Here’s our message from Jordan: We moved into this property about 5 …
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.
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.
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
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.
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.
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. 😊
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.
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 article 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?
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.
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.
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.
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
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.
You can see where the water is streaking down the wall. This is condensation. It’s beading up then rolling down. Rising damp slowly wickes water to the surface and makes it damp, it doesn’t form beads of water that then roll down due to gravity. The wall looks the same as condensation on a window where the beads form and when they get large enough, they roll down the window. Same thing happening here just on a wall.
It looks like an end terraced house 2 rooms up and 2 down, of around 100yrs old. I have just bought one in Northumberland, with back yard…anyway, my point is…that people should install a heat recovery ventilation system. I live on Norway and we all use this heat recovery ventilation system. It changes the air in the house several times an hour, removing the heat from exhausting air and adding it to the incoming fresh air. They are remarkably efficient and very cheap to run. They make the house comfortable to live in. I will soon install one in my house in Lynemouth Northumberland. Ps I followed your tip about the dry rod as my house was built with a damp course but over the 100 years it has deteriorated.
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.
Sweating Roger, unfair you cant see roof . All guess work with those photos but water ( and I’d lean condensation route) . Efflorescence on 130 year brick now ? That block wall is holding sme water but until you see how water falls an hits it your guessing. But 90%+ condensation damp. Easy fix but do it quick before spare sweat patches find a damp weakness then it’s all different approach. Get confident with your builder is a must…… and always always show a roof .
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.
I have just bought a victorian house to do it up. Dare I say it, i’ve done well and sorted out the damp issues (really wasn’t bad to begin with thankfully) apart from one horrible cupboard that I haven’t cracked. It’s got the water supply pipe in there, the gas pipe etc.. some idiot has decided in the past to smash off all the plaster right back to the brick wall in there, which is damp. I’m thinking the condensation is the main issue, the wall changing temperature in different weather (particularly when it got hot recently) and the cold pipes etc. First thing I will have a go at is venting it properly to see if that makes any difference but it’s hard to know exactly what’s happening there.
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.
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″?
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!
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.
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 website 👍
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
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 article on PIV installation?
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 .
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.
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.
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.
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.
Absolutely condensation. I consult with Waterproofing Specialist and always look for ventilation. Open a window and let the moisture out. The clients consistently say, “I paid a lot for the heating; I’m not wasting my money by letting it out”. The answer they get is not always what they want, but ventilation is the cure.
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.