Found a mould problem in the corner of our bedroom

[Mr Jack]

Noticed a spot of mould on the wall in the bedroom earlier in the week, so decided we'd pull everything out and deal with the problem, and discovered this:

Hiding in the corner behind where the wardrobe was, along with a load of mould growing up the back of the wardrobe and a few more spots hiding around the place. That's the outside corner of the wall. The carpet there (left from the last owner, btw, it's on the list to replace but behind a bunch of more urgent stuff) is noticeably wet. It's been very wet here lately, so I suspect that's probably made things worse. I've put a dehumidifier in there to dry things out, and then I think our next steps are:

Remove the wallpaper and either re-wallpaper or paint, after treating with an anti-fungal agent.
Throw away anything that is mouldy.
Make sure that we replace with furniture that allows better airflow to that wall.
Heat the room more of the time.
Try and figure out whether there is anything wrong on the outside that I can do to help.

It's a 300-year old thatched house so some problems are expected, but this needs to be dealt with. Any suggestions from others with more knowledge and skill than me welcomed!

 

[Rob_B]

I'd not re-decorate until you know what the problem is, it'll get damp again in no time if you have a leak or moisture problem, not amounf of fungicidal paint will change that.
Without knowing the layout I can only suggest the usual things, any guttering leaking or overflowing onto the soffits? (or whatever equivalent you might have?) any signs of staining on the ceiling? Heating the room if you have a leak is going to make things worse unless you ventilate the moisture (and heat) out regularly.

It *could* just be a damp room so dehumidify/ventilate well as you already know.

 

[Mr Jack]

I'd not re-decorate until you know what the problem is

Fair point.

Without knowing the layout I can only suggest the usual things, any guttering leaking or overflowing onto the soffits? (or whatever equivalent you might have?) any signs of staining on the ceiling? Heating the room if you have a leak is going to make things worse unless you ventilate the moisture (and heat) out regularly.

Thatched houses don't have guttering, it just sort of drips off and runs away. I'll see whether there's any pooling of water around that corner next time it rains and whether there's anything I can do about it. Nothing on the ceiling, and it's dry above, so I'm pretty sure it's coming through the walls or from below.

 

[Rob_B]

Thatched houses don't have guttering, it just sort of drips off and runs away.

Thought it might be something like that, it's not dripping onto the outside wall is it?

Lift the carpet, see what the state of the floor is there, would be unusual for it to come up from below with no signs of water in the carpet or room below (I'm assuming there isn't) but I guess it's not impossible.
Do you have a wider shot showing how far the mould comes out from that point, if nothing above or to the sides then could just be general 'moisture'

 

[Mr Jack]

Thought it might be something like that, it's not dripping onto the outside wall is it?

I don't think so, but I'll check when we have some rain. Normally the wind blows from the other direction but we did have strong winds and snow/rain against that wall a couple of days ago.

Lift the carpet, see what the state of the floor is there, would be unusual for it to come up from below with no signs of water in the carpet or room below (I'm assuming there isn't) but I guess it's not impossible.

It's a ground floor room, and there's no cellar in that part of the house to check. I'll rip up the carpet and see what I can see later.

Do you have a wider shot showing how far the mould comes out from that point, if nothing above or to the sides then could just be general 'moisture'

Hard to take a pic with all the furniture in the room. That's the only bit where it is really bad, but there's some spots all along that wall, mostly behind where there was furniture that would have blocked the airflow.

 

[Rroff]

One thing I would say, dispose of or very thoroughly remove mould on any furniture affected by it - when I moved house I brought a wardrobe along which had stood near a window and got a little mouldy, thought I'd cleaned it up, though I didn't really go to town on it, but it brought a mould problem along with it - after a few months found the wall mouldy behind it (which has never been a problem before that I can tell or since) and mould growing on it again where it was before - I just disposed of it at that point as it had seen better days anyhow.

As a general point, though it isn't really its intended use, I find as a last resort Green Gone works really well for internal mould as well.

 

[mickyflinn]

Any plants, bushes outside where the damp occurs ?

Cracked brickwork or rendering?

 

[SpellowHouse]

Many houses have issues with walls, that you don't notice until you restrict the ventilation or turn the heating down so evaporation stops. Damp can even cross a cavity wall in the right circumstances.
Take a look at the outside and see if you can spot any issues. Do you think the damp is getting through the wall, rising from the ground, or whatever, and treat that. This may be something like digging the soil away and coating with a bitumen based paint or perhaps using an anti-damp product on the wall higher up. Once you have done that, then you have already taken most of the steps. Don't put the wardrobe back! Leave the area well ventilated.

 

[fastwunz]

I hope those walls are lime plastered? If not, then the walls can’t breath, moisture can’t escape and hey presto, you have damp.

Also check:

1. Make sure the external ground levels are below the internal threshold
2. Make sure all air bricks are clear
3. Make sure no bushes or other foliage are growing against the walls
4. Check the mortar pointing or render externally for cracks or failure
5. Keep furniture away from solid external walls so that a clear flow of air can be achieved in these areas thus promoting the drying out of saturated walls

 

[radderfire]

Looking at the state of it, I'd say you definitely have a water ingress issue into the wall. If could be a problem with the roof and water running right down the wall, it could be the pointing in the brickwork needs redoing. Whatever, there is a big problem and you have to find the cause. As others have said, it's not just a case of cleaning and improving ventilation, although the mould problem wouldn't have been so great if you didn't have furniture against the wall, as there would be more evaporation from the wall.

 

[radderfire]

If you can hire a thermal imaging camera, you can point it at the wall to show where the cold spots are, and hence where the water is getting in:

Infrared Thermal Imaging Camera | Best Thermal Cameras

Find the best thermal cameras for your job. Fluke thermal imaging cameras for electrical inspections, home inspection, water leaks, and more.

www.fluke.com

 

[Mr Jack]

Any plants, bushes outside where the damp occurs ?

There was, although it's all been removed for a while.

Cracked brickwork or rendering?

We had the whole house re-pointed in summer, so that should be fine now. The house doesn't really have proper foundations - it was built before they did that, so I think it's probably a drainage problem on the outside.

One thing I would say, dispose of or very thoroughly remove mould on any furniture affected by it

Yeah, the wardrobe is toast, unfortunately. I think the rest is okay but we will check throughly, and we're planning on swapping out the two small bedside cupboards we currently have for tables so we can get better airflow. Not sure what we'll do for wardrobe space, though, I think anything we put there is going to limit circulation, even making sure it's further from the wall, and well I need somewhere to hang things. We'll have to see if we can figure out a different layout for the room.

As a general point, though it isn't really its intended use, I find as a last resort Green Gone works really well for internal mould as well.

When I search for Green Gone, all I find is this... which doesn't seem relevant unless I'm missing something!

I hope those walls are lime plastered? If not, then the walls can’t breath, moisture can’t escape and hey presto, you have damp.

I have no idea, we haven't done more than re-paper that room since we moved in. There seems to be plasterboard with some spacing to the actual wall - when we get rodents they run around in during the night, and it sounds hollow. I guess we might have to rip that out to get to the source of the problem. That'd be a right pain.

 

[Rroff]

When I search for Green Gone, all I find is this... which doesn't seem relevant unless I'm missing something!

Green Gone Path & Patio Cleaner - it is designed really for use on hard outdoor surfaces - but as a last resort it will blitz mould on just about anything and prevent it coming back for quite a long time unless the area is constantly damp, but using it on surfaces it isn't intended may or may not be ideal :s

 

[jellybeard999]

Initially, dry the area out as best you can and clean the mould. Astonish Mould and Mildew spray is pretty good - around £1 from home bargains. I'd sray it on and scrub the wall, then mist over it afterwards and just leave it to do it's thing.

I'd get rid of the carpet, or cut the corner off to dry that area out (especially if you're already planning to replace it immediately). That will allow you to check the floor below (concrete or timber?) and also help identify the source of the moisture.

What is the ground like outside? Paving? Concrete? Soil? Dig a channel if you can to let the external wall dry out. If this resolves it, you can then consider the best approach - drainage channel, bitumen paint, gravel etc

Are there any likely sources of water above? Leaky guttering? Leaky roof or bay window?

 

[KompuKare]

I assume the walls are solid, so any internal rendering has to have been done really well or would just hide things. IMO, you have to at least see what's behind the plasterboard. Solid walls and normal roofs with guttering etc. are bad enough but thatched too!

Heating the room if you have a leak is going to make things worse unless you ventilate the moisture (and heat) out regularly.

I've become a firm fan of desiccating dehumidifiers in the believe that if a room needs bit of heat then the (max) 500W or so one consumes can both heat and dehumidify it at the same time.

As for gutters: as it happens searching for "reetdach norddeutschland wände" does bring up a suggestion of "Warum haben Reetdächer keine Dachrinne?" so it seems everyone expect them.

Any thatched houses I have seen always have huge overhang and a slight pointing down of the outer reeds so that must be the guttering for those roofs. I would hope with some kind of gravel and "French" drain to catch water and somewhat divert. Since the reeds require regular replacement (for more often than tile or slate roofs), gutting would keep getting in the way there and besides no soffits to attach them too.

That search did throw up a video about Reetdachhäuser in Nordfriesland:

[Doku] ReetdachhaÌuser in Nordfriesland

Reetdachhäuser in Nordfriesland, Norddeutschland bauen. Nicht nur im Sommer ein Hingucker, sondern auch im Winter. Der Reetdachdeckermeister Rolf Feddersen e...

www.youtube.com

which possibly explains why looking for walls got me nowhere: there are all kinds of building with thatched roof there not just what I would expect from the UK and more so Ireland, that is only old solid stone farmhouses. No looks like in Nordfriesland plenty of far more modern brick houses are thatched too. Although for those I would expect a proper foundation and even a cellar.

As for suggestions: nothing really to add. If the ground is soil, I too would dig down and investigate as @jellybeard999 suggested.

 

[Mason-]

We had the whole house re-pointed in summer, so that should be fine now. The house doesn't really have proper foundations - it was built before they did that, so I think it's probably a drainage problem on the outside.

Repointed with lime mortar I hope and not sand and cement?

You said the house is 300 years old, the original mortar would not have been sand and cement.

Problems caused by cement pointing of stonework or brickwork

Damp problems caused by using cement to point brickwork or stonework. Cement should never be used as it traps water into the structure of the wall which needs to breathe through the mortar joint, and if cement is used, this stops the process.

www.heritage-house.org

The fact you had that done in the summer and then this winter you get damp is highly suspicious to me.

 

[Mr Jack]

Worrying thought, @Mason- :/ . Although I don't think it's a new problem, I think it's been there a while but was just completely hidden behind the wardrobe so we didn't notice until it spread.

I've ripped the wallpaper off and there's no sign of mould behind, or even any real sign of damp. In a display of incredible intelligence I did this before pulling up the carpet and checking behind the skirting which meant I wasn't sure whether the water there had run off the walls when I was taking the wallpaper off, but I think it came from the wallpaper, mostly, as there was no sign of mould or damp that I could see. Once it has dried off I can check again and see how it is looking.

Outside the bricks at the bottom of the wall feel a bit slimy and green, so I think there's a drainage problem there and it's also an area which won't get much sun to dry it out. Also, for some reason, that section - which is between the house and the road - is raised, so it's 10-15cm higher than the rest of the ground around the house and so the floor rather than being above the ground level is about the same as it. Not sure whether that could cause a problem? I'll wait until we get some rain and then go out and see whether I can see what is going on.

 

[Chabsy]

"Behind the wardrobe" I think that is the problem, lack of ventilation

 

[fastwunz]

Solid brick walls are vapour permeable and it’s absolutely imperative that they remain so.

They naturally allow a degree of moisture in but also allow moisture to wick back out - provided this equilibrium is maintained, you won’t have a problem. That’s why none permeable cement based mortars and modern plasters are completely wrong for particularly old dwellings. Lime mortar and render is permeable so ideal for solid brick walls.

Based on what you have said though, it strikes me that this is just a simple case of a warm room, cold external facing wall and a lack of air flow leading to water condensing on the wall because of the furniture being too close.

Remove the furniture, let it dry and keep furniture away in the future and you should be ok.

 

[jellybeard999]

As above, this does sound like cold walls and condensation, but I'd still look to rectify the ground level issue you mentioned with a drainage channel, french drain or similar.