Rising Damp: How to Recognise It and What to Do

Updated on April 12, 2019
Paddycat profile image

The author of this article is a mother of four and grandmother to four who is now enjoying her retirement in France.

An Overview

If you are experiencing problems related to damp in your home, it is important that you read the symptoms correctly. There are various causes of damp, but one of the more serious underlying problems is rising damp.

This is caused when moisture from the ground rises vertically up through fine pores in masonry or brick walls in a wick-like fashion, which in hydrology terms is called capillary action. Water can rise up the wall to a height in excess of 1.5 metres.

Once this happens, the moisture affects the plaster in internal walls which is highly absorbent. As groundwater contains dissolved salts, when the water evaporates, these are left behind in the wall and on its surface.

These salts fall into three categories:

  • Sulfates: These appear as a floury crust on the wall which is unsightly, but do not cause any damage.
  • Nitrates and chlorides: These 'hygroscopic' salts absorb moisture from the atmosphere and are invisible. Unless these salts are removed, even if the underlying cause of the rising damp is dealt with, the problem will not be cured, as they will continue to draw moisture in.

Above left, the horror of rotting floorboards hiding beneath the carpet. Above right, plaster that has bubbled and cracked due to damp.
Above left, the horror of rotting floorboards hiding beneath the carpet. Above right, plaster that has bubbled and cracked due to damp.

Diagnosis: 10 Signs

How can you tell if you have rising damp? The following are typical symptoms:

  1. Mold on walls and furniture
  2. Rotting window frames, skirting boards or floorboards
  3. Wallpaper that lifts
  4. Paint won't adhere to the walls
  5. Stains/tidemarks on walls
  6. Flaky or bubbling plaster
  7. White powder or crystals appearing on the surface of the walls
  8. Damp or wet patches appearing on the walls
  9. Crumbling mortar between bricks or stonework on the exterior of the building
  10. Rusting steel and iron fasteners.

The Dangers

If the rising damp is extensive, structural damage can result. The photograph to the right shows a gap of approximately an inch between the stair and the skirting board. This is due to the sagging of the rotting floorboards that support the staircase. There is a danger that the floor will collapse completely.

In addition, health problems can arise for those living in a damp property, such as allergies and respiratory illnesses caused by the growth of dust mites and molds.

Above left, staircase subsidence caused by deterioration of the supporting floorboards and to the right, a rotten skirting board.
Above left, staircase subsidence caused by deterioration of the supporting floorboards and to the right, a rotten skirting board.

Identifying the Cause

First, you have to find out where the moisture is coming from and how it is getting in.

If the dampness begins at ground level or below, it may be that your damp proof course (DPC) may be faulty. If your property has suffered subsidence, it is possible that the DPC could have been damaged. Some older properties do not have a DPC at all, or if they do, a physical membrane may have failed or been bridged. To find out whether this is the case, you will need to make a more in-depth investigation, but before you do so, it is best to eliminate all other possibilities first.

Consider the following:

  1. Ground levels surrounding properties can rise over the years as garden debris accumulates, and home improvements like decking and driveways are added. Check the outside of your property to make sure that all surfaces are not carrying water to a level higher than that of your DPC. All surfaces abutting the walls of the property should be slightly sloped so that rainwater drains away from the building.
  2. If you have cavity wall insulation, check that this has been properly installed. It should not go below the level of the DPC.
  3. Broken or blocked guttering, drainpipes, roofing, and flashing contribute greatly to damp, causing water to leak onto walls.
  4. Check that there are enough airbricks around all sides of the building and that they are not blocked. They should be positioned every 180cm (5ft 11in).
  5. Check the brickwork/rendering, etc., of your chimney for any damage to the waterproof surface.
  6. Check that kitchens, bathrooms, and boilers are well ventilated to carry condensation away. Dehumidifiers work very well in removing moisture from the atmosphere.
  7. Check that waterproof sealant and grouting is intact in between walls and shower trays/bathtubs.
  8. Check pipework for leaks, particularly at joints.
  9. If damp is appearing in walls above a fireplace, it could be that hygroscopic salts are drawing moisture in.

Courses of Action

Once the source of moisture has been identified, the first thing to do is to remove it. Leaks and external rainwater goods like guttering and drainpipes need to be fixed. Good ventilation through rooms and beneath floors must be re-established, and all drainage issues addressed.

It's only once the above issues have been addressed that a new damp proof course should be installed if deemed necessary. After that, any remaining rotten internal woodwork should be removed and replaced, and walls repaired and redecorated.

A Word on Internal Walls

If the damp has been caused by condensation, it is not necessary to remove plaster. It is sufficient to clean it and allow it to dry out. The next thing to do is to add a coat of fungicidal paint containing zinc oxychloride (ZOC) before adding your chosen decorative finish.

If the problem has been caused by rising damp, however, it is strongly advised that all old plasterwork, which will contain the moisture-attracting hygroscopic salts, is removed. When re-plastering, a plaster mix containing a silicone-based waterproofing, fungicidal additive should be used.

In cases where it is not practical to remove the old plasterwork, there is a product called Platon plaster base, which is a clear, high-density polyethylene membrane. The idea of this is to isolate the old plaster from the new, eliminating the need to remove the old hygroscopic masonry.

My pretty old French property has no damp proof course.
My pretty old French property has no damp proof course.

Beware of the Sharks

If you are unable to carry out the work yourself, you will need to call in an expert. But be careful. There are many firms that purport to be able to solve damp problems, but rising damp is often misdiagnosed. Sophisticated sales techniques exist to persuade unsuspecting people to pay for expensive damp treatments that may not be necessary. Even if the correct diagnosis is made, the products being sold may not be suitable to address the fundamental causes of the problem.

Many companies offer a free appraisal and diagnosis, but it is in the interests of commission-based salesmen to diagnose major problems, even where there are none, or to sell specific products produced by their companies which do not address individual needs. The best thing to do is to find a reliable independent expert to come and advise you.

To illustrate this point, I was recently quoted almost 8,000 euros, or over $11,500, to have a system involving the insertion of ceramic tubes at intervals around the exterior of my old stone-built French property. That price was not for the whole house, by the way, just for the two worst affected rooms. It was made to sound like a perfect solution, with the salesman offering an insurance policy valid for 30 years (which I would have had to pay for), and a promise that if any damp reoccurred within that time, I would get every centime back. He also offered an easy payment package.

However, this particular company's solution would have not solved my problem, as the damp was originating from underneath the building. If the salesman had bothered to look behind the property, he would have seen that the guttering needed replacing, and that water was collecting in a gulley behind the house. His solution of dealing just with the walls at above ground level would not address the underlying cause of the damp.

Even allowing for the fact that the work was covered by an insurance policy, once he had clinched the sale and earned his commission, that would be the end of his firm's responsibility to me. When the damp resurfaced, as it most certainly would, I would be left with the hassle of claiming on the insurance policy, and I'd be out of pocket until (or if) that paid out, not forgetting the continuing monthly installments until the issue was resolved. And on top of all this, I'd be back to square one with the damp problem. I dread to think how many people have been caught out in this way,

So do be careful, and remember, if your wall looks all right, it probably is. If it has any of the symptoms described above, you may need to look into things a bit more thoroughly, but make sure you get good independent advice. Good luck.

This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.

Questions & Answers

  • I have powdery and flaking walls, is this rising damp?

    Powder and flaking on walls coated with plaster are caused by saltpeter. Saltpeter is the accumulation of soluble salts on the surface of the wall, and this damages masonry and wall coatings. These salts are transported to the surface by ascending moisture.

  • My entire house feels damp but especially the first floor and the corners of my walls in my first-floor master bathroom are rusting, and the paint is peeling off. Do you have any thoughts on what might be causing it?

    It could be some things, and it's impossible to give a diagnosis online. However, simple things like drying washing indoors and steaming vegetables can have a huge impact on the level of humidity in a property. Also, good ventilation is essential. Make sure that your property has air vents and that these are not blocked. In the meantime, it might be worth investing in a dehumidifier to help alleviate the problem.

  • Why are you printing this nonsense? Rising damp is a myth, and all your proposed remedies will make damp walls worse.

    Though in common parlance, you are right to imply that the term 'rising damp' is perhaps misleading. 'Rising damp' is in fact just plain 'damp.' There is no one magic remedy. Every property is different, and there is a need to identify and tackle the underlying cause in each case.

  • Do the floors have to come up to cure a property's rising damp?

    As with any issue of damp, you need to trace where the source of the problem is coming from and tackle the problem from the root. There are many causes of damp. If the source is under the floorboards, some or all of the floorboards may have to be removed. However, damp problems can emanate from things like leaking pipes, chimneys, etc., and even lifestyle issues can have a bearing, such as drying clothes indoors, steaming food, etc., and not airing the property properly. French properties typically have no damp-proof course or air bricks for ventilation. In my old French house there were multiple issues causing damp problems. I had to pull up all the floorboards which exposed bare earth below before contracting builders to install a waterproofed concrete floor. This helped, but I had to have a French trench dug behind the property to help with water drainage and have the rotting windows and doors replaced to prevent water ingress.

© 2009 Annabelle Johnson


    0 of 8192 characters used
    Post Comment
    • profile image


      3 years ago

      Use the mold layer in wall and use the gypsum in half below that is good to remove the damp problems in house and building and more detail visit this link http://www.buildershampshire.net/damp-proofing-sur...

    • profile image

      Robin Jones 

      3 years ago

      Thanks for sharing this informational article. It is important to do regular inspection to avoid problems related to fireplace and chimneys. You can call professionals to do the inspection. To know more have a look here - http://www.chimneygenie.com

    • profile image


      4 years ago

      its so educative thanks

    • profile image

      audrey thomas 

      4 years ago

      my house is rented had black damp in bedroom for 6 years damp sealed it still comes back

    • profile image


      5 years ago

      In response to Ladisci, although the post is old I may be able to provide some helpful info to others. Basically the surveyor was an idiot. Any high readings around the chimney area on his "moisture meter" would most likely have been Hygroscopic salts in the plaster, not a failed damp course. The damp meters they use should be banned as they are almost totally useless for the job unless you are highly skilled in their use. They measure electrical conductivity and salts will give a false high reading. If it is an old house and the fireplace burnt fossil fuel then these contain salts that eventually leach through the brickwork into the plaster. If it is not damaging the decorations then no action is needed at present. Otherwise the area can be replastered with an aluminium membrane underneath.

    • profile image


      5 years ago

      Can anyone help please I think I may have damp on an internal wall which is also a supporting wall that is dead in the middle of our terraced house it is only on that wall I didn't think internal walls could get it..Lesley

    • profile image


      6 years ago

      Hi your post is very useful i found it very hard to diagnose the cause of the mystery damp patches but with a lot of internet searching i found a product called the wet wall warning and it proved it was only condensation

    • profile image


      7 years ago


      We have recently sold our house, and the survey done by the buyer shows that we have "high level" of damp on our chimney breast, lounge and kitchen and the report said that the cause could have been a failed damp course. Now the problem that I have is that we do not have any sign of dampness at all. For us was a shock, as we didn't have any idea! We have no patches, no flaky plaster or wall paper, no tide marks or similar. also we have have a gas fire, so the chimney breast is not capped and therefore I believe some water my come in, but I believe is normal. However now the buyer is having another report from a specialist, should I be worried, am I missing some other signs, a part from the ones reported by the damp reader? Thank you in advance! Laura

    • crystolite profile image


      9 years ago from Houston TX

      Nice information,thanks for writing.

    • profile image

      Peter Jackson 

      9 years ago


      Your post is very helpful and in your single post you have informed about the symptoms, causes, and the most important how to treat this problem? Rising damp is a very dangerous problem for both the houses and the property and needs to b treated with full care and properly. The best way to treat this problem is to recognize the source of the problem (leakage sources). climatic conditions play a major role, particularly in the levels of the exposure of buildings and their location near the sea or in a marine environment. In the earlier days the historic buildings are constructed without damp proof course. The water present in the ground moves up the wall carrying with it various salts. The upward movement of this water can cause saturation and can result in damage to timber, plaster etc. The wall is made made up of porous materials which easily absorb the water. Specialist damp proofing companies needs to be called which will provide the treatment for rising damp. They suggest the surface treatment for rising damp and the re-plastering on internal walls using dense mixes combined with water proofing agents.


    This website uses cookies

    As a user in the EEA, your approval is needed on a few things. To provide a better website experience, dengarden.com uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

    For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at: https://maven.io/company/pages/privacy

    Show Details
    HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
    LoginThis is necessary to sign in to the HubPages Service.
    Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
    AkismetThis is used to detect comment spam. (Privacy Policy)
    HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
    HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
    Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
    CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
    Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the googleapis.com or gstatic.com domains, for performance and efficiency reasons. (Privacy Policy)
    Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
    Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
    Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
    Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
    Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
    VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
    PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
    Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
    MavenThis supports the Maven widget and search functionality. (Privacy Policy)
    Google AdSenseThis is an ad network. (Privacy Policy)
    Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
    Index ExchangeThis is an ad network. (Privacy Policy)
    SovrnThis is an ad network. (Privacy Policy)
    Facebook AdsThis is an ad network. (Privacy Policy)
    Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
    AppNexusThis is an ad network. (Privacy Policy)
    OpenxThis is an ad network. (Privacy Policy)
    Rubicon ProjectThis is an ad network. (Privacy Policy)
    TripleLiftThis is an ad network. (Privacy Policy)
    Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
    Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
    Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
    Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
    ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
    Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)
    ClickscoThis is a data management platform studying reader behavior (Privacy Policy)