Damp and condensation – don’t always believe what you are told about ‘rising damp’!

Have you ever received a surveyor’s or a damp-contractors report only for your heart to sink when you read that they have found evidence of rising damp? Perhaps you have been told that your only (expensive!) course of action to remove damp is to chip off the plaster, inject chemicals into the wall, leave it to dry and then re-decorate?

If so, you may be interested to know that this diagnosis is often wrong and there is a more simple and affordable way to solve the problem.

At VapourFlow we have been designing, manufacturing and supplying ventilation and condensation control products for two decades. During this time we have worked with some companies who provide excellent technical insight into damp issues and who passionately challenge the efficacy of chemical damp proofing and seek to highlight the problems of dampness misdiagnosis. Two of these in particular provide a service and knowledge base well worth exploring:

Heritage House Ltd. – old property care and restoration specialists.

David Hewitt – damp diagnostic services.

Heritage House Ltd. is headed up by Peter Ward and provides specialist restoration services to owners of old properties across England, Wales and Scotland. They are also damp and condensation investigation specialists.

They have NEVER, in ten years of undertaking surveys, recommended any form of chemical damp proofing and have found that ‘rising damp’ rarely, if ever occurs. Instead they have found that condensation related issues are the cause of the vast majority of damp problems and that these problems can be traced back to human activity within the house. Peter and his team carefully examine the property, find damp and condensation problem areas, and provide detailed reports which explain both the cause of dampness issues and the recommended solutions. In most cases, controlling humidity is high on the list of solutions and his company use VapourFlow products wherever possible when restoring old homes. Peter’s website is a mine of information about damp problems, and explains in detail the pitfalls of using damp companies.

David Hewitt MRICS of the Dampness Diagnosis Consultancy provides impartial and accurate professional diagnosis of alleged dampness. David’s consultancy seeks to challenge established dampness diagnostic practices and completely eliminate the need for costly chemical solutions for his clients.  He has successfully appeared as an expert witness in a number of legal cases to dis-prove the occurrence of rising damp – and defeat substantial financial claims against his clients.

David practices independently and his clients include a number of major property insurers, management companies, ecclesiastical advisors, housing associations and very many owner-occupiers. David will provide a report and a specification for remedial works from established solutions and, where suitable, recommend VapourFlow products for condensation and ventilation issues.

12 thoughts on “Damp and condensation – don’t always believe what you are told about ‘rising damp’!

  1. Amy 2 says:

    Hi Ray
    I came across your website while researching what I should do about damp spots that are appearing in 3 separate places upstairs in our house. They are at the top of the walls where the roof meets the walls. Could this be a condensation problem or a re-roofing needed? We do have terrible condensation running down the windows every morning in the winter months. I’ve had one roofer telling me its condensation and another telling me its because there is no felt under the old part of the roof. The bathroom fan is supposed to come on when the humidity levels are high enough, but it doesn’t do this often enough and we have no kitchen fan. I thought condensation points only happened at the base of a wall – is this true?

    • pj says:

      Hi Amy,
      Sorry for the delay in response, I have been
      This is not true. Any moisture in the air will be attracted to the coldest parts of the house, due to this you will see the most condensation in these areas. It is not uncommon to see damp spots forming at the joining of walls and ceilings.
      In my opinion, one of our Warm Air Dehumidifiers in the bathroom, used in line with our Vapour Vents, would form an effective solution to the problem that you currently have. The Warm Air Dehumidifier combines the the functions of both extraction and in-take of air, with the added benefits of warming and drying the incoming air if the temperature outside is below 14 degrees. This being the standard setting, as soon as the built in Autostat registers the rise in Relative Humidity (rather than the Absolute Humidity that your current fan is registering) the fan will turn into extraction mode. With the use of the vapour vents in the same system, you will be creating a positive pressure atmosphere, with the air being replaced by fresh dry air.
      To further increase the effectiveness of this system, a fan could be introduced into the kitchen area, such as a Wolf K Kitchen fan. The Wolf K is an extremely energy efficient fan, with high extraction rates, which is fully automated again by our Autostat.
      If you have any other questions, please do not hesitate to contact us.

      Peter Dickason

  2. caroline anderson says:


    in winter in the hills of the algarve the outside humidity is high although not especially cold although the temperature change in a single day to night quite significant. the upper floor of our house there has thin, cement rendered walls built in the 1990,s on top of a much older traditional lowerfloor .It is a single large space with large single glazed windows. damp and condensation during the winter cause mould and blown wall paint and the walls feel wet to the hand, the older floor downstairs is relatively ok, the floors are only linked via an external staircase.
    I am about to paint the outside with a mineral based Nordic paint to keep water out , it is supposed to breathable, but still need to reduce condensation internally , it is currently a single ,raftered space of about 50 square metres. tiled floor, bamboo and wood lining to concrete and tiled roof. what do you rec from your product range? thank you,

    • Ray says:

      Hi Caroline
      The condensation with the consequential mould would be best controlled with our warm air dehumidifier range of products, the air these products would infuse in to your property will only be heated by 200 watts when the air goes below 14oC externally (when your property envelope is cooled and prone to condensate).
      You may have an extractor fan already in your bathroom, in this instance replace this with our bathroom warm air dehumidifier WAD-B, this will extract when the light is on or when you have a shower or bath and bring in fresh air at all other times.
      In your roof space our attic version would also be advised, this will provide air intake, prewarmed when cool outside, this extra air movement will further inhibit mould production by reducing the spores in the air by dilution and providing drying air through to your living area. This unit is the WAD-A

      Ray Hudson

  3. Moll says:

    Hi Ray,

    I am in desperate need of some sound advice before I blow what little savings I have on a damp course. I am a pensioner and you don’t have to read the papers every day to see how we get ripped off right left and centre. I live in High Peak in a 100 year plus end terraced stone cottage with stone floors. I recently had a surveyor survey my cottage for a perspective buyer. I asked him while conducting this survey should I have any concerns. He said no, apart from some minor damp which was showing from the metor reading and he suggested a damp course. I had read part of your article about a year ago when I was having some pointing done and asked the question about chemicals and damage to old stone. He just said they don’t do it like that now but didn’t go into detail. What ever he put in the report frightened the buyer off unless I knocked 10 to £15000 off the asking price she was withdrawing the offer. Which obviously I can’t do. I know there is a bit of a damp problem on the bottom of some of the walls as when I knock it’s hollow and I fear that it is getting worse. As this is my home and I don’t want to live in a damp one I am about to contact a damp proofing specialist. The other thing is I am going to redecorate one of the rooms and I know when I start stripping paper off a load of plaster is going to come off too, I don’t have paint on the skirting or doors as they are pine. I have engineered wood flooring in the lounge and laminate in the dining room as I have a dog I have had some pointing done but trying to find a builder who uses lime cement was like looking for god. I just don’t know what to do to solve this problem. Can you help? Any advice would be very much appreciated as I am on a small budget.
    Many Thanks,


    • Ray says:

      The expert in the field is Peter Ward of Hertaige House http://www.heritage-house.org/
      He without a doubt is your first port of call – he carries out surveys at a cost – but at least you will know then what you spend will be providing a solution to your needs rather than a solution to someone’s profit margin.

      We cover condensation (and often this is a root cause) however, in older properties in particular, other factors need to be carefully considered such as when any part of the property is subterranean or external ground material is higher on the outside than internal.
      Many of the solutions will involve our warm air dehumidifier range. Once we know the envelope of your property is keeping water out then we can guide you with the best warm air vent system for your property.

      Typically Warm air dehumidifier in the bathroom and a Dryvent K in the kitchen enabling a cross flow of prewarmed dry fresh air.

      Ray Hudson

  4. Andrew Miller says:

    Hi Ray, In our house we have problems with mould on walls behind furniture. I instaled laminate flooring over timber floor boards and wondering if this is causing a problem with air flow.The wall does not feel wet but wallpaper is peeling off. Central heating is oil fired with wall mounted radiators, windows are double glazed and mould forms on the sealer between the plastic frame and timber surround. Nothing can be stored under the bed as condensation forms between the item and the surface of the flooring. Any comments would be helpful.

    • Ray says:

      Hi Andrew

      The new flooring would reduce your ventilation and increase humidity levels, and therefore increase the probability of condensation and increase surface humidity with the consequence of mould.
      It is very likely you had some issues prior to laying the new flooring and would suggest tackling the issue with a ventilation solution – our most effective combination is a warm air dehumidifier in the bathroom and a dryvent k continuous extract fan in the kitchen, this can be reversed with a Warm air dehumidifier WAD-K in the kitchen and a Dryvent B in the bathroom, this is usually done when we have insufficient room in the bathroom as the Warm Air dehumidifier is 230v and needs to be outside of zone 1 & 2.
      The ventilation system will provide a positive flow of prewarmed fresh air in to one room and extract in the other causing a gentle exchange of air that provides a healthier and dryer environment to live in, you will find a significant positive difference in your living environment. Every situation is different and we cannot guarantee it will solve all your condensate issues, however this is without a doubt the best way forward.

      Ray Hudson

  5. Wayne bester says:

    Hi Ray

    We have bought a house in the lakes which has 2 basement bedrooms and a shower toilet room,we have been told that it was tanked out 10 years ago but no proof of this,there is no mould on the walls just a few damp patches,there is however a damp smell down there,the shower does have a extractor fan,I do not know if this goes to the outside though,what can I do to stop the damp smell ?



    • Peter Dickason says:

      Dear Wayne,

      Thank you very much for your comment.

      This is a common issue that is seen throughout the country.

      When dealing with any areas that are subterranean, it is best practice to ensure there is an air replacement for any air that is extracted. The main reason for this is that just extracting for the area will create a negative pressure, which can lead to water ingress through the fabric of the building.

      The most efficient way to ensure that this is happening is to use a system like the following:

      Warm Air Dehumidifier Kitchen (WAD-K)
      Dryvent B

      In your case, switching the fan over in the shower area (once it is established it is vented to the outside), for the Dryvent B and have a fresh installation of the WAD-K at the furthest point from the shower area possible, will create a cross-flow ventilation, whilst still providing a higher intake rate than extract.

      It would also be an idea for you to visit the Heritage House website where Peter Ward and his team have extensive knowledge of properties and issues within them.

      If you would like to talk further, please email me peter@vapourflow.com and I would be happy to talk this through further with you.


  6. peter says:


    I am looking for a ventilation system for our cellar. We have had problems with wood rot and woodworm previously and have replaced flooring and joists throughout our ground floor. I have looked at whether installing air bricks would benefit but have mixed research results i.e. many saying its a great way to ventilate however from other research the response is that it doesn’t do enough, particularly in summer months where the warm air would enter our cold cellar to cause condensation (how much of that is true I do not know). After visiting the Heritage House website and watching many videos, a continuous message seems to be to install a ventilation system. What is the best product you would advise can be used to ventilate a cellar? Thanks.

  7. Phillip Thompson says:

    Hi Ray I am interested in buying your heated bathroom fan to lower humidity on our hall, stair and landing outside wall. Usually measures 60 to 70% at 19deg. It is solid wall 1908 build detached house. The wall is rendered and north facing. Since removing wood panels for replastering and decorating we quickly got mould on the matt paint finish top half. The silk lower section is fine. My question really is what humidity level would be safe from mould and would the heated bathroom fan achieve it. The mould is very uniform in pattern all over and not behind pictures so I can only assume from condensation. DG window do condense on cooler days too. Thanks.

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