Advice please - mould/condensation solutions

sxp842

Hi all, I’d be grateful for some advice on our mould/condensation problem.

We live in a first floor 2 bed flat. There is one floor above us. The building is quite an old large converted property.

We have a recurring problem in our bedroom with mould and condensation. Our bedroom has 2 external walls, and both walls have fairly large windows. These external walls are really cold in comparison to the other walls. In the winter we used to get large damp patches on the corners of the external walls and black mould growing there. Last year we painted that part of the wall with damp / mould resistant paint, and since then the damp patches have stopped and mould has drastically reduced. However, we still get slight mould on the walls and the windows are covered in condensation every morning on the winter and we have black mould on the frames. Other rooms in the flat get a little bit of condensation but nowhere near as bad, and no mould. This goes for other room which have 1 or 2 external walls and large windows. It seems to just be an issue with our bedroom.

We have a humidity measure in our bedroom and the humidity is generally between 60 - 70% ( interestingly when we move the measure to another part of the bedroom away from the external walls the humidity reduces quite a lot). The humidity measure in the room next door is about 10% less. That room also has two external walls but only one window.

We have tried all the usual things like heating the flat enough, opening windows, closing the bathroom door after a shower, running an extractor, sleeping with our bedroom door partly open. None of this is getting the humidity below 60% in our bedroom. I don’t think our double glazed windows have trickle vents and it looks like the air vent in our bedroom may be blocked up. Even in the summer when the mould / condensation problem is not an issue, our room always feels cold and unpleasant, even when the rest of the flat feels warm and cosy. I think it is something to do with the external walls being very cold and possibly the air in the bedroom being humid or damp.

We don’t know how to fix this problem - both the mould/condensation and the general unpleasant feel of the room.

We have a couple of ideas

• buying a good dehumidifier (query if this would be a solution on its own)
• Installing internal insulation on the bedroom walls (would probably help make the room feel nicer, but not sure if it would help the humidity)
• Installing a positive ventilation system suitable for a flat (generally read good reviews about PIVs but not sure if it would be suitable for our flat and situation)

Does anyone have any advice on the above solutions and which might work best for us, or any alternative suggestions?

We are having a baby in a few months so keen to get this problem solved soon!

karatepet

I have the same problem living in a flat.Only the bedroom gets damp and condensation on the windows.The humidity in the morning is about 80%.I have bought a dehumidifier and run it in the day and humidity soon falls to 60%.Also the walls feel alot drier to touch
I bought this
.https://www.amazon.co.uk/Avalla-X-125-Dehumidifier-Aero-DynamicTM-Technology/dp/B09JGSTNST/ref=sr_1_3?crid=1VY0KUEZFFYJT&keywords=avalla+x-125+smart+dehumidifier+12l&qid=1672134838&sprefix=avalla+x,aps,93&sr=8-3
Next day delivery and easy to operate.

ThisIsWeird

sxp842 said:

We have a couple of ideas

• buying a good dehumidifier (query if this would be a solution on its own)
• Installing internal insulation on the bedroom walls (would probably help make the room feel nicer, but not sure if it would help the humidity)
• Installing a positive ventilation system suitable for a flat (generally read good reviews about PIVs but not sure if it would be suitable for our flat and situation)

Does anyone have any advice on the above solutions and which might work best for us, or any alternative suggestions?

We are having a baby in a few months so keen to get this problem solved soon!

Of your options, there is one that should provide the obvious cure, and not just remove symptoms, and that's the internal insulation. It should also save you energy, and make the room very noticeably more pleasant to be in. Couple it with checking that the floor isn't draughty - if you are replacing the carpets, then consider lining it all first with 8mm fibreboard underlay, sealed between the sheets and especially around the room perimeter - draughts often come in via the gap under the skirtings.

That leaves the ceiling, tho' there's a reasonable chance that's ok in terms of insulation.

sxp842

Thanks for the replies. That’s really good to know about the internal insulation - we’re willing to spend some money on this but just want to make sure it will solve the problem. 

Would it be worth coupling that with a dehumidifier? Not sure how practical it will be with a baby sleeping in the room though. 

Any views on the positive ventilation system?

jennifernil

The noise of a fan running in a dehumidifier may well help the baby sleep!      Our 2 grandchildren both sleep to something that sounds like falling rain.

ThisIsWeird

sxp842 said:

Thanks for the replies. That’s really good to know about the internal insulation - we’re willing to spend some money on this but just want to make sure it will solve the problem. 

Would it be worth coupling that with a dehumidifier? Not sure how practical it will be with a baby sleeping in the room though. 

Any views on the positive ventilation system?

I would hope that, with internal wall insulation (tho' check that it's compatible with your house wall type) would fully negate the need for a dehumidifier. Some trickle ventilation would still be required, but I'd expect your condensation issues to reduce dramatically, and cease to be an 'issue'.

A well insulated house, coupled with a reasonable amount of background heating and controlled ventilation, should just not have condensation problems.

A dehumidifier consumes power, obviously, and largely just removes moisture that shouldn't really be there in the first place. A PIV system will cost a fair amount to install, has some running costs, lose you some internal heat as it constantly displaces the inside air - it's a type of forced ventilation - so also uses additional energy. Added insulation costs to install, but should then save save save.

The other thing to look at is how effectively you reduce the production of moisture in the first place, or have it removed at source before it goes around the house. Mostly obvious stuff like having an extractor fan running throughout the use of a shower, and for a good ~10 minutes afterwards until the room is completely dry. Ditto when you are cooking. Not air or radiator-drying clothes inside the house unless the room is well ventilated, and things like that.

A lot of this can initially appear counter-intuitive. For example, if you turn off a bedroom radiator throughout the night, close the door, and crack open at least one window to 'vent' setting, you are unlikely to have condensation/damp/mould issues in that room. It'll be darned cold through the night - yes - but largely dry, as all the moisture getting in there is ventilated away before it condenses out. You keep warm by being under a duvet, and have the bedroom heating timed to come on a half-hour before you get up. I'm not, of course, suggesting that for a nursery, but then a wee baby isn't likely to be producing that much moisture anyway!

Alnat1

Might be worth getting a window vac to slurp away the condensation in the bedroom very quickly in the mornings. They are also handy in the bathroom for tiles and shower screens.

Won't solve the problem but can remove a decent amount of water in just a minute.

_Sam_

ThisIsWeird said:

I would hope that, with internal wall insulation (tho' check that it's compatible with your house wall type) would fully negate the need for a dehumidifier. Some trickle ventilation would still be required, but I'd expect your condensation issues to reduce dramatically, and cease to be an 'issue'.

A well insulated house, coupled with a reasonable amount of background heating and controlled ventilation, should just not have condensation problems.

A dehumidifier consumes power, obviously, and largely just removes moisture that shouldn't really be there in the first place. A PIV system will cost a fair amount to install, has some running costs, lose you some internal heat as it constantly displaces the inside air - it's a type of forced ventilation - so also uses additional energy. Added insulation costs to install, but should then save save save.

The other thing to look at is how effectively you reduce the production of moisture in the first place, or have it removed at source before it goes around the house. Mostly obvious stuff like having an extractor fan running throughout the use of a shower, and for a good ~10 minutes afterwards until the room is completely dry. Ditto when you are cooking. Not air or radiator-drying clothes inside the house unless the room is well ventilated, and things like that.

A lot of this can initially appear counter-intuitive. For example, if you turn off a bedroom radiator throughout the night, close the door, and crack open at least one window to 'vent' setting, you are unlikely to have condensation/damp/mould issues in that room. It'll be darned cold through the night - yes - but largely dry, as all the moisture getting in there is ventilated away before it condenses out. You keep warm by being under a duvet, and have the bedroom heating timed to come on a half-hour before you get up. I'm not, of course, suggesting that for a nursery, but then a wee baby isn't likely to be producing that much moisture anyway!

I'm wondering about the bits in bold, for example looking at the weather report now the outside humidity in my area is 84%. Let's say the house is well insulated and ventilated, but the air it ventilates with is very humid? Why is this not regarded "moisture" that shouldn't be there in the first place?

(I have to add I'm a big fan of our dehumidifier )