Ventilation

[Everly18]

The home we've recently moved into seems prone to condensation, mainly in the front bedroom and dining room which we use as a sitting room. I can't seem to find an actual answer as to how long should you ventilate the home for, is it best to leave windows open slightly all day in the rooms that suffer the most or just for short periods of time throughout the day? We've also not been using the heating so not sure if switching it on now and again would help too?

Get a decent dehumidifier.

We have a decent dehumidifier in the front bedroom but i hate leaving it on all day, especially if we're not home, it also seems quite costly to run but it's a few years old now so maybe it's time to buy a more energy efficient one.

Ideally you should heat and ventilate. If you don't heat rooms you will get damp. If a rental property your LL will not be happy you are causing damp by no heating. Using a dehumidifier will help as sucks moisture out of air but uses electricity to run.

If it’s your own house more insulation on the walls and then some heat. Is the source of the moisture general living or is there a leak or no expel air in a bathroom or kitchen?

How can you have condensation when there’s no one at home? That’s very odd. Basically there’s excessive water vapour in the air that condenses on the cold walls snd windows. That’s why there’s often condensation found in bathrooms from hot water usage and bedrooms from breath! So what is causing water vapour during the day? Get to the bottom of this snd you have a start.

Have your window got trickle vents installed? They are not a security risk. Make sure all rooms are ventilated by air bricks. Unblock fireplaces if they are blocked up. Vents in walls have covers you can open and close. Get double glazed windows if you don’t have them. Ensure you have insulation that doesn’t clog vents.

You need to balance your water vapour production overnight with breathability of your house. .

I'm hoping the damp walls are caused by condensation. there is definitely some condensation going on as the windows especially in that front bedroom are often full of condensation and the room feels damp ifykwim but we're also not sure if penetrating damp is coming through in some areas in both those rooms i mentioned, these damp patches only appear after we've had rain, they dry up then it rains again and they reappear in the exact same spot/pattern. I thought If we can solve the condensation it may solve the damp patches on the walls or it won't and its actually an issue with the external walls. The first pic is of one of the larger patches on the wall on the external wall in the front bedroom and the second pic is in the dining room, on the same external wall, this drys up and almost goes but comes back up in the same place and pattern especially during bad weather. Do these look like damp caused by condensation or like something else is going on?

Definitely looks like penetrating damp, not condensation. Sorry. The rain is a dead giveaway. Could be something easy to resolve like gutters etc.

I'm not heating much at the moment only half hour before bed time in the bedroom and a couple hours in the evening in the living room and bathroom. Bedroom window open most of the day, living room window open twice a day for half hour, bathroom window open an hour after my bath. Window air vents open whenever we're not in that room. Washing is either on the line all day, in the tumble dryer, or underwear goes in the bathroom with the window open for a few hours until most of the wet has evaporated out of the clothes. If you're drying washing inside you'll need the windows open more often/longer and the window vents open constantly.

Get a damp meter, they're cheap in DIY stores, I'll bet you've got a damp problem. Look to move if it's rental because you'll never feel properly warm and your heating bills will be higher, you could also start losing clothes and furniture to mould as well as it affecting your family's health. There will be mould spores in the air even if you can't see any, if you have a damp problem.

Ah that's not good, I was just hoping it's the condensation, I wonder if that's why there is so much condensation then, if the walls are constantly damp during bad weather. It is rented, we waited a long time for one big enough for us in this area to come that's close to the school and we've spent a small fortune decorating and replacing the stinky carpets. I'll email the landlord but i don't suppose it will do much good, I bet they're already aware.

I've been outside and had a look and it appears the pointing is not in the best condition, the mortar just crumbles if I run my finger across it, It's not raining atm so i can't see if there's a leaky pipe or anything so I'll have another look when it's raining but i can't see that the landlord would be willing to pay out for repointing unfortunately

I am a LL and I can tell you condensation is caused when hot steam hits cold. Like boiling pan on cooking hitting cold air. Then it condenses and settled on a cold surface like a window or wall. Do you use extractor fan in kitchen when you cook? If you dry wet washing hanging in bathroom you should leave windows open in bathroom all the time. Every time anyone baths or showers you need extractor fan on during shower and half an hour after too. If mortar is crumbling ask ll to replace. But I can tell you I have had tenants who ventilate and heat properly. They tell me no damp. Next tenant does not ventilate or heat enough, drys wet washing hanging up indoors then complain of damp. Damp is often down to how a tenant uses property. More ventilation and more heating on is key. I know heating is expensive but government is paying you £66 ponds per month to heat your property ATM. That extra heating should mean house not damp. You could always look for a different property if you really think house is the problem.

But this sounds like damp coming through the walls after rain. Not from not ventilating properly.

There's no extractor fan in the kitchen, I'm not sure why but there wasn't one when we moved in, I do open the window in the kitchen when cooking though as the windows tend to steam up if I don't. I also don't hang dry washing indoors, I hang outside if it's a dry day and/or use the heat pump tumble dryer, I empty the water draw between each use or sometimes in between if I'm drying towels, the tumble dryer is also right at the back of the house in the extention so it's in a small room and I have the window open while using it, I don't like having clothes hanging everywhere or on radiators as they annoy me, I did buy one of those heated air dryers a few years ago from lakeland, I'd say I've used it a handful of times as I just prefer to use the dryer as its easier and quicker. Again for the bathroom, I open the window when the bathroom is being used and it gets left open for an hour or so afterwards. We didn't have any mould or damp issues in the previous house we lived in for 16 years so I don't think it's anything in particular that we could be doing to cause so much condensation, we live the same as we did in the previous house. We've not had the heating on really as we've not really needed it as even though it's been wet and miserable the temperature has been quite mild, sometimes I'll pop the heating on for 10 mins in a morning to get the kids up for school if it's really nippy but it's not really been cold enough to have it on.

That’s definitely not caused by condensation. We had awful issues with condensation - to the point we had water dripping down our bedroom light fitting! Had no electrics upstairs for 2 years whilst we saved to sort it out- and was all set
to tell you to get air tiles fitted into your roof (air vents / tiles) and open your windows as much as you can, but looking at that that’s definitely more serious damp, sorry. The photo where it looks like it’s coming along and down the edge of the ceiling, is that an upstairs room? I’d check your gutters and the gable along the edge of the roof.

Those pictures are not penetrating damp. I lived in many houses with damp issues so fairly good a damp!
are the gutters ok and not dripping? Any cracked or slipped roof tiles? Are the walls single skin? If yes the damp can come straight through. If the painting needs doing that is probably the cause.
Heat does help with penetrating damp but you need lots of heat like a log burner on constantly.

The photo with the damp patch towards the ceiling is in the upstairs bedroom, there's no guttering along this wall as its the side of the house and the roof slants towards the front of the house and the back so the guttering is along the front and back of the house. There are other patches along that same wall, there's a large one that looks similar to this with the pattern but it's less prominent, this one dries out much quicker then the other ones and then there are smaller singular patches that are similar to the second photo I posted of the dining room just smaller, but they are all on that same side wall of the house. I can't see if there are any tiles missing because it's quite a tall house, but it may be worth having someone have a look up there, I can't see any leaks in the loft though.

The bedroom was decorated a month ago at the most, so the wall is newly lined and painted. The previous paper was peeling off with some mould underneath but the landlord told us it was due to the previous tenants not ventilating properly. I'll attach a pic of the large patch that's half way down the wall but further away from the ceiling patch and of one of the smaller singular patch that's near the window. I took the pics yesterday evening though so they may be difficult to see.

I suspect, looking at those new pics, you’ve had cavity wall insulation done badly. If it isn’t done well you will have pockets of empty wall where the cold air will create damp pockets. Try and find out if this is the case - if you rent though you may not be able to do much about it. The landlord may be trying to say it’s ventilation but that doesn’t seem to be the case from the pictures you’ve posted.

Thank you, i'll try and find out about the cavity wall insulation. Would It be possible to use damp paint over the areas where it's coming through or would that create more problems?

You could do but I don’t think it would solve it long term. The damp will eventually seep through. We have similar patches in our kitchen. It’s not ideal but we found wallpapering over the damp patches with a dark, patterned wallpaper the best way to hide it. But obviously we know it hasn’t “solved” it.. I think ideally you’d want someone to fill in the areas where the wall insulation isn’t evenly filled.

I don't see the point of cavity wall insulation. Buildings are built with two layers of bricks with a gap between for a reason. Then people come along and fill in the gap with cavity wall insulation and before long start to wonder why they've got damp 🙄

The previous paper was peeling off with some mould underneath but the landlord told us it was due to the previous tenants not ventilating properly

Landlords always try to blame tenants. Repairs are costly.

Next time try to rent somewhere not freshly decorated. If it's full of scuffs as dings but no signs of damp, that's better. Freshly decorated often means trying to cover up a damp problem. I speak from experience, too many rotten rentals around. Buy a damp meter and test properties before you agree to move in.

Because then the cavity fills with freezing cold air in winter, which in turns makes the inside wall cold and creates condensation due to the dew point being on the inside wall. I wonder why building regulations insist on 100mm min cavity wall insulation on every current new build/ extension ? 🙄

without seeing the property it’s hard to tell what the problem is, but it looks like penetrating damp... it could be a roof,guttering or brickwork issue but there’s definitely a problem somewhere.

Can you get into the loft. See if the damp is on the beams and underside of roof. Does the wall face west ie the prevaiing winds so the rain is being blown against the wall. If it is and there is loose pointing rain could be coming through wall though would think that's pretty unusual. How old is the house?

I have an old house, and due to a bizarre layout struggled hugely with condensation. We got air bricks fitted, left windows open in all weathers, will get a vent in the roof at some point, and have a dehumidifier and are on top of it but ours never looked like that. Ours would be that virtually overnight the wallpaper would go mouldy and start peeling but the plaster underneath in all but the worst area was bone dry. That looks like somethings getting in?