Mould/condensation and dehumidifier help

Fleabag

Hi all,

After hours of searching online, I still haven't found a suitable solution to my problem.

I've been in my current home for 2 years, a 3 bed semi built in 1894. In the 80s, the owner made various alterations, including removal of the chimney breasts and, it appears, removal of air bricks (suggested by a painted rectangular area high on the bedroom wall) . It has double glazing, which I think is due for replacement at some point. Cavity wall insulation has been put in at some point. Two rooms in the house were bare plaster when we bought it (And still are!), which I believe was due to extensive mould damage on wallpaper. Blinds in other rooms show signs of black mould stains, too.

Having been here a while, we have observed that mould is forming in the colder months on most (all?) windows in the house. Going by my observations and removal of wallpaper, I think the worst areas are the rear bedroom (which we and the former owners use as the master, as it's marginally the largest) and the small extension off the kitchen, though I think this is probably a little better for us, as I use this as an art studio, whereas the former owners seem to have only used it to keep a fridge freezer. This room is the only room to not be included in the central heating system, having a wall mounted gas heater instead (which I do use in the colder months). However, I have valuable steel tools in this space, so it's particularly important to eliminate any excess moisture in the environment.

In the winter, mould forms on windows throughout the house. I think the dining room (which forms the access between hall & kitchen) and kitchen are the least affected, but front lounge, rear extension, bathroom and all 3 bedrooms all get mould forming on the windows and frames and lots of condensation in the winter. There are no leaks and no discernable moisture on any walls. Clothes, carpets etc do not feel damp or smell musty.

When affected, I do clean the windows and frames with bleach, which tends to suppress mould growth for some time, but it's obviously not addressing the cause.

I'm aware that a dehumidifier is addressing the symptoms, not the cause (which I want to address too, as finances permit).

I've ordered a 4-5 bed house dehumidifier, which is obviously marketed as a product that will address the problem throughout the whole house, but when I search for information on optimum placement, I just get results telling me to put it in the worst affected area, which isn't terribly helpful. My instinct says the landing may be the best spot (though I accept it may include siting it in other areas at regular intervals), but my main concern is that the rear ground floor studio is a considerable distance from the landing (as the air flies!). As moisture is removed from upstairs, would other moist air from downstairs replace it to be dehumidified?

The unit is 13 or 14kg, so not something we'd want to be moving between floors on a daily basis (I do hope to use it in the front bedroom on laundry mode as needed - we don't have a dryer).

Surely these units must draw moisture from whole houses if they're marketed as per the size of house they're suitable for, but I'm struggling to understand how a unit upstairs can even out the humidity throughout the whole ground floor - or if I place it centrally on the ground floor, will it be able to resolve the problem upstairs.

Any help would be gratefully received
(Sorry for the length of the post, but thought it best to give a thorough overview from the outset)

armchaireconomist

Just place it in the most central location and make sure to leave doors open and windows shut in all affected locations.

sevenhills

Fleabag wrote: »

I've been in my current home for 2 years, a 3 bed semi built in 1894. In the 80s, the owner made various alterations, including removal of the chimney breasts and, it appears, removal of air bricks (suggested by a painted rectangular area high on the bedroom wall) . It has double glazing, which I think is due for replacement at some point. Cavity wall insulation has been put in at some point. In the winter, mould forms on windows throughout the house. I think the dining room (which forms the access between hall & kitchen) and kitchen are the least affected, but front lounge, rear extension, bathroom and all 3 bedrooms all get mould forming on the windows and frames and lots of condensation in the winter.

When affected, I do clean the windows and frames with bleach, which tends to suppress mould growth for some time, but it's obviously not addressing the cause.

Perhaps you have ventilation in the form of an extractor fan in the kitchen, but do you open the windows in other rooms?

Fleabag

Sevenhills, we do have an extractor in the kitchen (I admit, I haven't used it that much, as the noise really irritates me, but have been trying to do so more recently). We open windows in the summer, but of course this isn't a time when condensation is forming. I do try to open windows as & when I can through the winter (particularly in the bathroom after use), but naturally, this isn't ideal when the heating is on and I assume that lowering the heat will further exacerbate the problem of condensation forming on windows.

Areas of the house do struggle to get to a comfortable temperature - the lounge because the radiator barely warms up (doesn't need bleeding. Think it needs a flush through). Bedroom feels cold, even when the hall, stairs & landing are warm (I tend to leave doors open to rooms in regular use to help the heat spread, but also worry about turning heating off & closing doors to other bedrooms between uses every fortnight, as I assume this will encourage condensation & mould)

Fleabag

I have wondered if one of the first jobs on the list to actually address the root cause might be to have air bricks reinstalled, but I assume previous owners had a reason why they removed them - perhaps damp & mould that wasn't corrected by the air bricks removal

sevenhills

Fleabag wrote: »

I have wondered if one of the first jobs on the list to actually address the root cause might be to have air bricks reinstalled, but I assume previous owners had a reason why they removed them - perhaps damp & mould that wasn't corrected by the air bricks removal

I have airbricks and vents on the bedroom walls, it does make it colder, but I dont suffer with any damp or mould.
If the moisture is not because of rain seeping in, then its likely to be caused by poor ventilation.

Fire_Fox

What are your window frames made of? Metal without a 'thermal break' will act as a 'cold bridge'. Wooden frames are obviously more porous to water than metal or plastic.

Mould growth suggests the affected areas are staying damp. For the bedrooms thoroughly dry each window every morning, with kitchen roll (throw away) or several cloths (do not air dry indoors). Ideally open windows daily - esp. wooden ones - to finish drying out.

The root cause of condensation is our modern lifestyles: the average family releases litres of water every day. We can't stop breathing (!) but we can have shorter or less frequent showers, use lids on pans, dry laundry outside or in a tumble dryer. Our ventilation strategy is in addition to this.

Fire_Fox

For new builds or older properties that have been 'sealed up' to reduce drafts, experts recommend a ventilation strategy
1. Purge ventilation (opening windows and/ or external doors)
2. Background ventilation (eg. airbricks, trickle vents in windows)
3. Mechanical ventilation (eg. bathroom extractor fan, kitchen cooker hood, dehumidifier).

There are systems that crossover, such as positive input ventilation (PIV) and heat exchange ventilation (HRV or MVHR) . These units are on all day every day, use a low level of electricity spread throughout the year, conserve heat, quiet to run. But obviously installing this is more expensive than just using the windows and extractor fans you already have more often!

Air flow within or around a home is highly variable: where the windows and external doors are, how much these are used, if internal doors are closed or open, the layout of the rooms, and so on. The further is it from your dehumidifier to a given room, and the more corners turned, the less effective the dehumidifier is likely to be.

that

Fire_Fox wrote: »

The root cause of condensation is our modern lifestyles: the average family releases litres of water every day. We can't stop breathing (!) but we can have shorter or less frequent showers, use lids on pans, dry laundry outside or in a tumble dryer.

...and cook with the kitchen door that often leads into the lounge closed and the kitchen window wide open - made a big difference to me!

Fleabag

Our windows are double glazed - I think put in some years back. Just bog standard plastic frames as far as I can see. There's no extraction in the bathroom, only the kitchen. I admit, I do tend to leave doors open most of the time, except when I turn off radiators and close off the 2 other bedrooms to conserve energy on the heating. We don't have a tumble dryer, and do sometimes dry clothes indoors when it's too wet to hang them out (hopefully the dehumidifier will easily deal with that).
I suppose I have reservations that one unit, even more powerful than recommended for a house of our size, will be able to draw moisture from a room so far removed from it.

Fleabag

Re: addressing the cause, I see advice to maintain the heating (in the past, I've tended to try to do without it to save on heating costs when home on my own during the day and only put it on in the early morning & evening) and different advice to open windows - Obviously, opening windows means I can't maintain a higher temperature in the house.

Ultimately, I want to resolve the cause, even if that does involve some initial expenditure (my last, terraced, 1930s house, with similar ventilation but better insulated was always warm with minimal heating and never suffered condensation or mould).