The incidence of true rising damp Vs Induced rising damp

I  am often asked how common rising damp is and after being asked again today I wanted to outline my thoughts on this issue, since we have a damp proofing industry operating in the UK, which operates on the premise that rising damp is a common occurrence. In fact it is incredibly rare and a review of the academic text relating to this question led to the following academic review…

How common is rising damp?

 It’s important to examine the incidence of rising damp in order to understand the size of the problem. Oxley T A, and Gobert E G (1999, p.7,8) state that awareness of dampness has also been stimulated by the rise of a service industry of ‘specialist’ firms devoted to curing it. This is an industry largely directed towards curing rising damp. This is a competitive industry which uses a lot of publicity; it has spread quite widely the impression that rising damp is the main cause, or at least a very frequent cause of dampness in buildings. In fact rising damp is a relatively uncommon cause of dampness in buildings.

The 1991 English House Condition Survey carried out by The National House Condition Survey Group (1993, p.54) found that one fifth of the stock is reported as experiencing problems associated with damp. In almost two thirds of these dwellings the problems relate to rising or penetrating damp, in the remainder the problem is condensation.

Table 2.1 (below) further clarifies this by showing that 12.6% of damp properties are affected by rising damp.


Table 2.1 Problems with Damp                            

                                                                               Thousand dwellings (%)


Problem                                                             Number of Dwellings     %

Condensation/mould growth only                                 1560                     (39.8)

Rising damp only                                                          494                     (12.6)

Penetrating damp only                                                   780                     (19.9)

Combination of the above                                             1087                    (27.7)

Any problems                                                                 3921                   (100.0)


% of total stock                                                                                           (19.9)

Source: English House Condition Survey (1991)

Oxley T A, and Gobert E G (1999, p.1,2) state that, we have good reason to believe that only about one third of all dampness problems are due to rising damp. They further explain; in the Protimeter laboratories specimens of wallpaper and plaster are received almost daily from surveyors and local authorities for chemical analysis for the presence or absence of certain nitrate and chloride salts, which are typical by-products of rising dampness. Salts are consistently found from year to year to be present in only about one third of all specimens tested. An even lower incidence is reported by Trotman P, Sanders C, Harrison H (2004) who state that rising damp featured in 5% of the 510 occurrences during the period 1970-74; 4% of the 518 occurrences during the period 1979-82 and 5% of the 520 occurrences during the period 1987-89, an average of about one in twenty of all (damp) investigations.

Oliver A, Douglas J and Stirling S (1997, p.186) give three reasons why rising damp is not as pervasive as other forms of damp:


  1. The majority of buildings in the UK have some form of original dpc. Even bridging or lack of continuity between dpc’s/dpm’s would cause only localised rather than widespread incidences of rising damp in a building.
  2. Failures of these dpc’s would need to be severe and extensive to cause major and general manifestations of rising damp in a wall. There is no evidence that suggests that such failures are occurring on a large scale.
  3. The problem of rising damp in walls caused by defective or missing dpc’s can be combated by reducing the sub-soil moisture content.


More induced rising damp caused by damp proofers.
More induced rising damp caused by damp proofers.

General academic consensus puts the incidence of rising damp in all damp properties at around 5% but our own view based on pragmatic experience of carrying out hundreds of detailed damp investigations, using the full range of diagnostic tools puts the incidence at significantly less than 5%. General speaking I believe that earlier investigators failed to understand the difference between true and induced rising damp, which would give a falsely high incidence. Lets assume 5% is correct though, even if this were true, one in twenty damp properties affected by rising damp is relatively rare. Practically speaking, we do not find true rising damp in anything like 1 in 20 damp properties. We may encounter three or four cases a year and for each case we almost always identify subterranean leaks and consequential high ground moisture levels as the cause.

Induced Rising Damp

Theres a great irony in that an industry, that promotes the incidence of true rising damp is in our experience, primarily responsible for causing it. However, this wouldn’t be true rising damp, rather, it is what we call ‘induced’ rising damp. Whenever waterproof coatings are applied to walls that prevent moisture evaporating from that wall then the moisture has nowhere to go but up. In these situations there is no limit to the rise height, as academically accepted to be the case for true rising damp and often the first sign of this problem is damp staining breaking through at the top of the finished waterproof plaster or render system, such as in the image below. The solution for this is to undo the work done by damp proofers and remove the cementitious render from the wall to reinstate wall base evaporation. We commonly encounter induced rising damp wherever we follow in the steps of damp proofers but we rarely encounter true rising damp and where building technical details are correct then it is usually caused by high local ground moisture caused by leaking drains (foul and storm) or leaking incoming water mains.

A classic case of induced rising damp
Unexplained damp patches at high level explained when plaster was hacked of to reveal an underlying waterproof render. A classic case of induced rising damp caused by damp proofers.

10 responses to “The incidence of true rising damp Vs Induced rising damp”

  1. Paul Kilvington avatar
    Paul Kilvington

    Hi Joe. I have just come across your website for the first time and read the above article about rising damp. I agree 100% with you thoughts and conclusions. Like you, we investigate lots of cases of reported rising damp but very few are true rising damp. We find most are caused by several factors including defective drainage (causing moisture sinks), plaster wicking (often due to poor site practice when re-plastering), and the use of cementious mortars and renders. This is a fantastic website and a really useful source of information for building surveyors, especially those in the early years of the careers. I will recommend this site when providing advice to APC candidates.
    Paul Kilvington MRICS – East Yorkshire

    1. Joe Malone avatar
      Joe Malone

      Hi Paul,

      Thanks very much for the kind words and I’m glad you find the site useful.

      Regards. Joe Malone

  2. Jon F avatar
    Jon F

    Thanks for the blog and interesting to read a balanced view. I’m interested in the cure as couldn’t really deduce this from what you have written…. We have a couple of chimney breast which both have powdery plaster and ‘damp’ stains and patches at the alcove corners. These occur at a relatively high level so suspect moisture is trapped by cementitious render behind the plaster. There is no obvious water source as the walls are internal party walls . There are no drains or water supply pipes locally. We have had the chimneys inspected and these are OK. Water table is low .

    We are going to hack the plaster/render off anyway as it is defective and expose the brick so we can investigate further. Is it a just case of using a breathable plaster ?

    Could air moisture be responsible?

    How do we go about finding a local surveyor who is able to offer a balanced view and give sound recommendations ?

    Thanks J

    1. Joe Malone avatar
      Joe Malone


      You’ve not had moisture testing carried out, using calcium carbide, and that has to be your starting point to understanding how best to proceed.

      A cure, involves having proper diagnostic work carried out, and removing the cause of the damp, rather than hiding the damp behind waterproof plasters or renders. which is what damp proofers do.

      There must be drains locally, or how is foul water taken away from the property?

      It may help to know where you are, I’ve had a number of competent surveyors who have attended my damp investigation courses, and who may be local to you.



  3. Denise M avatar
    Denise M

    My daughter is in the process of selling her bungalow built in 1986. She as lived there for four and a half years and the property was previously owned by my mother from new. At no time has there ever been any visible signs of any damp. When my daughter bought the property her survey done by an RICS surveyor (who incidentally did use a moisture meter) reported that the property was dry to normal and the dpc appeared to be doing its job satisfactorily. However, the person buying my daughter’s property recently had her homebuyers survey done and has pulled out because the property apparently has issues with rising and penetration g damp. We are baffled because there is absolutely nothing wrong. After reading your blog I am convinced she is being coned but what can she do?

    1. Joe Malone avatar
      Joe Malone

      Hi Denise,

      electronic hand held moisture meters should not be used in isolation to diagnose damp. High moisture readings with these meters, simply mean that further investigation is required to test for moisture at depth in the masonry.


      Joe Malone

  4. Paul Town avatar
    Paul Town

    Hi Joe
    I attended your damp course last year-terrific I would highly recommend.

    One question if there is cement render on the wall externally say two storeys
    of it -to reinstate the wall base evaporation what would you do with it?
    Also you said you were developing a product to deal with high ground levels
    in lieu of French Drains/ trench etc. Any Progress
    Anyhow thanks again for all your helpful posts Paul

    1. Joe Malone avatar
      Joe Malone

      Hi Paul,

      Thanks very much for the kind words.

      I come across this a lot Paul, and pragmatically, we can’t often remove all the render, but, it’s important to remove it from the wall base, to at least 150mm above external finished floor level. This often means that a bellcast bead would need to be installed, where the render has been removed. Of course, this would then need blending in with the existing render.

      Moreover, when render is removed from the wall base, we often find heavily spalled or damaged bricks which need cutting out and replacing, and/or repointing.

      No progress as of yet Paul, My design company pretty much closed down during Covid, so I couldn’t get the design drawings back. Something I hope to progress in 2021.

      Regards. Joe

  5. Jackie Hornby avatar
    Jackie Hornby

    Hi Joe,

    Very interesting read. We have damp patches on all walls in the living room. Rising up from the skirting boards to about 20-30cm. There are no signs of salts showing through. So far two companies have said it is rising damp. One has also said we need to dig out the soil abutting the front of the house and replace with aggregate to improve drainage.

    My question is, how can I be sure these companies are right. Who do I approach to have a professional impartial test done?

    Many thanks.

    1. Joe Malone avatar
      Joe Malone

      Hi Jackie,

      Neither is right since I guarantee that not one of them has tested for moisture at depth. Also replacing soil with aggregate is pointless because if you have high ground levels, then this is not a drainage problem, it’s lack of wall base ventilation that is the problem and aggregate will do nothing to improve that situation.

      Focus on the following:

      1. Make sure your external ground levels are a minimum of 150mm lower than internal finished floor levels.
      2. The masonry at wall base should be bare masonry… Not painted rendered etc, so as to ensure that you have critical wall base ventilation.
      3. If you have wall base damp, its almost certainly caused by a leak so consider the following:
      * Have a CCTV survey carried out on your drains.
      * Check your incoming water main for leaks. Is it lead or steel? Both should be changed.
      * Check your heating system for leaks. Are you losing boiler pressure? Do you have heating pipes buried in concrete?
      4. If you have floating timber floors have you got adequate subfloor ventilation? You should look for a airbrick every 2 linear metres minimum around the property perimeter.


      Joe Malone

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