Damp and mouldy house

Hi, tried reading the various other threads but wanted to start my own in case I'm missing something.

We bought an old cavity brick 1950s doer upper house in late 2020. Since then we replaced the old roof, replaced the circa 37 year old double glazing with triple glazing and decorated throughout. Last winter wasn't too bad but we're now having a huge problem with damp/condensation and mould in just about every room. Bizarrely the only room I haven't found a single bit of mould in is the bathroom. I did use a special anti-mould paint in there so I'm tempted to buy more for the rest of the house.

The main bedroom is the worst, there is severe condensation covering the whole of both windows, frames and cills every morning, dark patches along the celiing/ tops of walls and chimney breast on eternal walls (NE facing wall the worst).  Today I've discovered the inside of the wardrobes are soaking wet and mouldy and there is mould growing on the corners of the ceiling. 

Every morning the windows are wiped and opened for at least a couple of hours. Heating is on for at least a few hours a day as I have a toddler at home. I have some moisture catchers in the bedrooms but they don't actually catch that much water. We have an extractor in the bathroom and the window is opened after showers with the door shut so moisture doesn't spread through the house, same with the kitchen. 
We went away for a few days last week and came back to the bedroom window cills covered in black mould spots.

I'm currently trying to deal with CIGA regarding cavity wall insulation that was put in many years ago, we're on the coast in rainy windy Cumbria so should never have had it installed. Not sure if that's a contributer but I'll try anything.

I've lived in many old houses over the years and I've never had anything this bad before. Every day I seem to find something new that's grown mould and needs cleaned or thrown away. It's soul destroying when i think about how much money we've spent on this house. Can anyone help? (Sorry this is a bit of a garbled mess I've just had a tantrum at finding yet more mould and I'm ready to set the place on fire right now, not that it would burn... its too wet 🙄).


  • edited 12 December 2022 at 2:05PM
    grumblergrumbler Forumite
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    edited 12 December 2022 at 2:05PM
    Since then we replaced the old roof,
    What about the loft insulation?

    Last winter wasn't too bad but we're now having a huge problem with damp/condensation and mould
    Nothing changed really since the last winter except people started to save on heating. If it's not the case for you and your CH system works well, then the only possible reason, IMO, is more humidity sources in the house. Cooking and drying washing are the most common ones that can be addressed.
    Another source is breathing, reportedly 0.5-1L/day per person. This explains condensation in bedrooms, but is impossible to change.

    We are born naked, wet and hungry...Then things get worse. :(

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  • EfficianEffician Forumite
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    A few questions.
    Do your new windows have trickle vents.
    How draughty is your house.
    How are you heating the house & to what temps.
    Are you randomly opening widows in the affected rooms without checking direction of airflow.
  • MurraymoocowMurraymoocow Forumite
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    Thanks for the replies. It has been noticeably colder this winter, we've certainly had to put the heating on a lot more so far, otherwise its correct that nothing else has changed. 

    We don't have trickle vents, I did request them at the time but (like many other things) was basically overruled and told to leave the talking to the men. 

    Upstairs is quite draughty compared to downstairs. The hallway especially has very high ceilings but we checked the loft hatch and it's well sealed. 

    GCH is on around 1.5 hours in morning then similar again in evening. Rooms warm up quickly and boiler serviced annually/ rads all turned up and working. Daily temps around 17 to 18°c and nighttime bedroom is usually around 14°c but has dropped as low as 12°c.

    I've always just opened the windows and left them to be honest but they're on opposite sides of the room so thought airflow shouldn't be a problem. 

    My partner will be checking the roof insulation tonight, the roofer did say he would sort it at the time but I have a horrible feeling he hasn't. There were a lot of problems during the works that we only found out about months later (I was on the other side of the country giving birth at the time so not really paying attention). Its a very shallow loftspace with difficult access so I've never been up there myself.
  • jcuurthhtjcuurthht Forumite
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    triple glazing
    Do your new windows have a lower U value than your cavity walls? If so, the walls are going to get colder before the windows, resulting in water condensing on the walls instead of/as well as the windows. Ideally, if water is going to condense anywhere in your room, it should be on your windows.
  • macmanmacman Forumite
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    Heating is only on for 3 hours a day?  Even though it's at or below freezing at present?
    No free lunch, and no free laptop ;)
  • RobM99RobM99 Forumite
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    Water in wardrobes? Sounds like a major leak to me.
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  • MurraymoocowMurraymoocow Forumite
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    Not sure about U values but the worst wall does feel freezing cold just now when the rest of the house, including windows, is warm.

    The house heats up quickly and stays warm for a long while after the heating is turned off. I can certainly put the heating on for longer to see it it will help. 

    I have an oil filled radiator I'm going to set up in the worst bedroom for a few hours too to see it it dries out some.
  • FreeBearFreeBear Forumite
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    A damp wall is a cold wall - The moisture helps to suck heat out.
    If you can get the temperature up and run a dehumidifier, you may well find the problem wall starts to feel a little warmer.
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  • EfficianEffician Forumite
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    Murraymoocow said:

    I've always just opened the windows and left them to be honest but they're on opposite sides of the room so thought airflow shouldn't be a problem.
    The right kind of airflow is important.
    what you want is the moisture heavy air to remain as a vapour so when opening a window that damp air will flow out of the open window., more often than not when randomly opening windows for ventilation the cold air will rush from outside into the room you want to dehumidify & rapidly cool the rooms surfaces allowing condensation to occur on all surfaces , then at night you close the window & the moisture ends up back in the air , it;s gone nowhere just stayed in the room.
    when ventilating try opening a window in the lowest but warmest room in the house ( for us it's the lounge )but keep all other windows & vents closed you should feel cold air coming in, then open a upstairs window , bedroom /bathroom etc , you should feel warm air rushing out, 10 mins at this time of year should be plenty to introduce plenty of dry air though the lounge window. the new air will be quickly warmed as it's only the air we want to change while keeping the temp of the building fabric.
    If you have naturally cold walls windows then it's a good idea to have circulating fans to help keep the surface temps up whilst keeping moisture airborne as much less energy is needed to expel the damp air than evaporating condensation & then expelling.

  • Loza2016Loza2016 Forumite
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    If you don’t have trickle vents can open the windows slightly at night on latch. Still secure but will give a bit of ventilation. 
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