If you have a new account but are having problems posting or verifying your account, please email us on [email protected] for help. Thanks :)
Hello all! Please ensure that you are posting a new thread or question in the appropriate forum. The Feedback forum is overwhelmed with questions that are having to be moved elsewhere. If you need help to verify your account contact [email protected]

Black mould and dampness

  • 12-01-2023 1:05pm
    Registered Users Posts: 28

    Hi folks 

    I have a problem with condensation and black mould in my house. 

    I know from my research that it’s because of poor air circulation. 

    after doing a google search I’ve come into contact with the damp master and there going to call to my house in two weeks time to conduct a survey costing me 450€. 

    wha i want to know is have anyone used damp master before and were they happy with their work, price , equipment etc etc 

    thanks for reading my post and for your help in advance



  • Registered Users Posts: 6,312 ✭✭✭10-10-20

    I'd correct this "I know from my research that it’s because of poor air circulation. " to say "I know from my research that it’s because of poor air circulation AND human activities such as cooking and cleaning and drying clothes."

    That way you can understand that your activities are part of the reason why moisture is high. Addressing some of these - by drying outside or by using a dryer or using an externally-vented extractor fan during cooking - will reduce some of that moisture. 👍️

    Hopefully this helps.

  • Registered Users Posts: 2,814 ✭✭✭MicktheMan

    Not lack of air circulation but lack of effective/efficient evacuation of moisture is likely your issue caused by one or more of the following:

    • Homeowner's lack of knowledge on the natural physics at play and often being counterproductive because of this.
    • Excess moisture load
    • Insufficient heating maybe caused by excessive heat loss
    • Poor / ineffective ventilation.

    From experience, the only manner to successfully address which of these are the culprit(s) is to monitor & log the internal air conditions over a period of time (e.g. 2 weeks) and then using the data collected in conjunction with a visual / thermographic survey to make appropriate recommendations.

    Anything else is guesswork really and maybe a pushy sale of some ventilation system. Also, the more independent your advisor/surveyor is the better.

  • Subscribers Posts: 683 ✭✭✭FlipperThePriest

    Just to add a bit of background, the OP has posted this in the regional forums, and has blocked their vents. I suggested the OP should unblock vents and maybe look at reducing direct wind through vents.

    Good luck OP!

  • Posts: 0 [Deleted User]

    So they're charging you 450 euros just to have a look at it?

  • Registered Users Posts: 28 bruce thomas

    What they said was to carry out a survey to find out what’s the cause and then advise me on a solution

  • Advertisement
  • Registered Users Posts: 355 ✭✭Biker1

    So you are getting a company that want you to buy their product to do the survey. They are going to tell you that you need their product to solve the problem whether it is right for your issues or not. At least get independent advice if you are going to pay 450e for it.

  • Registered Users Posts: 12,097 ✭✭✭✭Calahonda52

    I would agree with Biker here and also with post 3 by MtM.

    Just to add my piece to the above: we need to consider the the level of insulation and the role of relative humidity.

    IMO I would ditch the damp mister call out for now, post some contextual pictures of the mould here and let's have a shot.

    Also tell us why kind of house it is.

    The resolution here is science/physics/ household occupancy/behaviour profile based and not product specific based which is what damp mister will offer.

    As for mould resistance paint....

    I have just finished surveying 50 houses in Kerry and am still learning about mould etc.

    “I can’t pay my staff or mortgage with instagram likes”.

  • Posts: 0 [Deleted User]

    The cause is insufficient insulation combined with inadequate or inappropriate ventilation. Warm moist air + cold surface= condensation = mould.

    The solution is insulation + ventilation. For ventilation, mechanical extract from the bathrooms & kitchen (ie where most moisture is generated) would give the most return on investment. The attic will provide the best return for the money spent on insulation.

    The best solution is to ensure air tightness (replacing doors & windows as necessary) and insulate all your external walls, your floors, your attic, and install a centralised mechanical ventilation heat recovery system with humidity sensors.

    You can PM me for my bank details so you can transfer the €450...

  • Registered Users Posts: 12,097 ✭✭✭✭Calahonda52

    So you want the OP to spend maybe 150k on a house that will still be worth what is worth before the 150k spend.😎

    “I can’t pay my staff or mortgage with instagram likes”.

  • Registered Users Posts: 28 bruce thomas

    Thanks for that

    the House is well insulated both walls and attic

    yes i agree that ventilation is key.

    as i said previously i blocked the vents in the walls of some rooms because they breeze coming in was unbearable.

    my question is could you recommend a ventilation system ie centralised mechanical ventilation heat recovery system

    are they like a heat exchanger in the attic pipped to each room.

  • Advertisement
  • Registered Users Posts: 28 bruce thomas


    upload pics later

    house was built 25years ago, with 2 inch areo boards in the cavity, and maybe 4 inches in the attic. About 10 years ago we got the walls pumped and extra insulation in the attic. It’s a 2 story building and 5 people living in it.

    as i mentioned earlier i did block the original vents in the walls as the breeze coming through was unbearable.

    i think that’s my problem and I’m asking would a heat exchanger system sort it out?

  • Registered Users Posts: 2,814 ✭✭✭MicktheMan

    Couple of points.

    Don't block vents.

    If unbearable breeze is coming through vents then you likely have a general air tightness issue throughout the house effecting your comfort and heating bills negatively (aka draughts). This is separate to insulation and should be investigated as part of the independent survey.

    The Vent Axia multivent range of central mechanical extraction systems are decent for your situation without breaking the bank and far superior imo to PIV systems I see advertised regularly. Forget heat exchangers or heat recovery systems if you don't have a handle on your air tightness.

  • Registered Users Posts: 28 bruce thomas

    Hi again and thanks

    can you explain to me what the centralised mechanical ventilation heat recovery system does and compare it to a heat exchanger please

  • Registered Users Posts: 28 bruce thomas

    Also can you advise me on who would i get to do an independent survey on this.


  • Registered Users Posts: 2,317 ✭✭✭XsApollo

    Have you a boiler inside the house?

    if you do ,is it gas or oil?

    You need big vents if you have a gas boiler inside.

    You shouldn’t really block your vents, especially if you have any type of boiler inside.

    maybe put a different vent on the outside that restricts the flow more.

    or alternatively I did this myself was put different vent on the inside that you can close and open.

    if it’s **** weather you close the vents , especially good at night, and open during the day or a more suitable time.

  • Registered Users Posts: 138 ✭✭New2Dubs

    We had similar problem with mould in bedroom which has 2 external walls. We realised we’d not been ventilating each day with fresh air because of the cold weather. Bought a dehumidifier online & have stopped drying clothes on radiator in bedroom. These 3 small changes have made a huge difference.

  • Registered Users Posts: 2,814 ✭✭✭MicktheMan

    Heat recovery is the process of extracting the heat from the exhaust air and transferring it to the fresh incoming air. This process happens in the heat exchanger.

    Don't get too hung up on this though, what you need is appropriate ventilation not necessarily the latest gizmo.

  • Registered Users Posts: 28 bruce thomas

    oil burner it’s outside

    I know i shouldn’t have blocked the vents but where i live i had to keep out the breeze coming through

    im looking for an alternative solution thanks

  • Registered Users Posts: 28 bruce thomas


    but I’m looking for a different solution to vent’s on external walls

  • Registered Users Posts: 138 ✭✭New2Dubs

    I didn’t mention vents (we hadn’t been opening windows) but good luck!

  • Advertisement
  • Registered Users Posts: 12,097 ✭✭✭✭Calahonda52

    Where are you living?

    This is key to seeing who might look at it.

    “I can’t pay my staff or mortgage with instagram likes”.

  • Registered Users Posts: 2,814 ✭✭✭MicktheMan

  • Posts: 0 [Deleted User]


    The tongue in cheek reference to the "best" solution was partly in reference to the OP's enthusiasm for throwing €450 for someone to come and try and sell him an expensive solution to his reasonably simple problem. It was also partly a reference to some posters insistence that the absolutely perfect, comprehensive, and model best practice solution is the only option that anyone should ever even consider possibly considering when addressing any issue. Which is ridiculous.

    If I was the OP I wouldn't want to spend Christmas dealing with the issue. 2 or 3 extractor fans in the bathrooms & kitchen plus a ton of insulation in the attic would be my approach— quick, cheap, effective, and guaranteed to completely horrify a significant proportion of the posters in this forum...

  • Registered Users Posts: 328 ✭✭mosii

    Hi ,I agree with this approach, open windows to ventilate but not too long, keep as much heat in the house. A dehumidifier will help .A meaco 10 L 180 euro ,cheap to run so dont be afraid to use .A big cause of condensation is drying clothes inside, on rads etc. If you put your clothes in a small confined area ,and use the dehumidifier to assist drying ,this will help. I was skeptical of dehumidifiers ,but they can collect a lot of moisture from the air, thus reducing condensation and mould. Best of Luck.

  • Registered Users Posts: 757 ✭✭✭C. Eastwood

    S - ( I + V) = C

    This is a simple way to explain Condensation.

    S. Steam

    I. Insulation

    V. Ventilation

    C. Condensation

    You state that your house is well insulated.

    And that you will open up the Vents

    Then the problem is Steam.

    This Steam is caused by the following:-

    1. People breathing
    2. Drying clothes on rads
    3. Steam from boiling water, boiling vegs, cooking, etc
    4. Baths
    5. Showers
    6. Tumble Dryer
    7. etc sources of moisture

    Clothes should not be dried in the house.

    Tumble Dryers must be exhausted to the external atmosphere

    During cooking- extract steam to the external atmosphere and have the Kitchen door closed to prevent any steam escaping in to other parts of the house.

    When finished having a Bath / Shower, open the Bathroom window / switch on a Mechanical Extractor and shut the door of the Bathroom on leaving.

    Also seal all draughts to prevent heat loss by Convection.

  • Registered Users Posts: 28 bruce thomas

    You haven’t read everything

    what family does everything that you say.

    in theory you may be right but in practical kids don’t open there windows first thing. Who closes doors when cooking. I’m out of the house very early every morning and late home. So I’m looking for another solution to ventilate my house during the day rather than opening windows and closing doors. Also most people i know are drying their clothes on a clothes horse. I’m no different to anyone else. I’ve a problem with air circulation and that’s why i have mould so I’m looking for better options. that’s what I think. Thanks anyway for your input.

  • Registered Users Posts: 12,097 ✭✭✭✭Calahonda52

    Steam is not the right word here, the correct terminology is water vapour contained in the air, which then condenses out as water when conditions are right: a combination of lower surface temperature and higher relative humidity as shown below.

    Steam has a minimum temperature of 100 degrees Celsius at normal atmospheric pressure.

    If you look closely at the spout of a kettle when boiling, you cant see the first few mm as its steam.

    Once the temp drops and the steam becomes water vapour, then you can see it.

    “I can’t pay my staff or mortgage with instagram likes”.

  • Registered Users Posts: 12,097 ✭✭✭✭Calahonda52

    did you post the pics and tell us where about you live yet?

    Re your comments, some of this will require behavioural change, we can't rely fully on tech, especially when it consumes more scarce energy

    “I can’t pay my staff or mortgage with instagram likes”.

  • Registered Users Posts: 1,049 ✭✭✭TimHorton

    Any Pic's. Had black mould along the edge of an external wall, Cleaned it with Vinegar/Baking Soda - I then went up into the attic and discovered the Attic Insulation near the eaves just above the mould was not fully there - Whoever put it down was too careful not to block airflow. I simply relaid half the length ensuring airflow remained but making sure I got good coverage - Hey presto 2 months later I have no mould on the relaid piece but on the part I did not remediate they black mould returned.

  • Advertisement
  • Registered Users Posts: 12,097 ✭✭✭✭Calahonda52