Cold, condensation and mould.....

Did you use anti-mould paint FC? I've found that to work well in troublesome places.

 

I have no doubt that she would - in fact, she is so conscientious that she would probably have the French doors replaced, the whole house re-plastered, and goodness knows what all else. If I can't resolve it easily, then I will get in touch with her.

Our @Zigs has very kindly given me a call, and on his excellent advice, we may well have a cheap and easy solution (bearing in mind that this is only an issue for a matter of weeks every year) - I will knock up a drawing tomorrow

I did, as well as using a Polycell specific mould treatment before painting. I must admit that the paint I used was own brand cheapish stuff and not Dulux that I would normally go for, so that may well have had a bearing on things.

 

Well anti-mould paint would only address the symptoms by suppressing mould growth, obviously the underlying cause needs sorting out if the walls are running wet. Trouble is if you apply heat to that area the condensation will just form on the next coldest surface it can find, which might be windows/glass. It's ventilation you need really, it's surprising how much water humans breathe out. Easier said than done as I know you said you are ventilating and with this current cold weather you can't leave windows open all day.

 

OK, my idea is as follows:

A box (wooden/plastic, won't really matter as long as it is reasonably air tight); A couple of holes in one side with two PC cooling fans mounted on those holes to draw air into the box; on the opposite side of the box, have one outlet and silicone in a piece of rectangular ducting; a small 12v regulated supply could be sat outside the box, with only the low voltage going in, and the fans can be connected in parallel - - I reckon I am looking at 0.25mA or less, so the consumption is next to nothing. This made small enough would allow me to hide one under each of the sideboard units, and the end of the duct could point out blowing a constant breeze at the walls beside the doors, giving permanent ventilation.




I also think our central heating setup has a part to play in this - currently, we have no thermostat at all, so the heating is either on or it is off; we do have TRV's fitted on the radiators, but they only 'just' cope with the size of the area that they have to heat, so almost invariably they are running at full tilt.

On really cold nights, the temperature can drop away as it pleases and will continue to do so until such times as the heating fires up in the morning; then, it is on for a short period and the cooling cycle begins again. Worse still, if we have a really, really cold night then our only option is to put the heating on constantly and it will heat and heat and heat to the point that the place may be over heated which probably increases the humidity as water evaporates from plant pots and breathing, then when the heating goes off and the room cools the air is less able to support that humidity and it lands on the coldest surface first.

Tomorrow, we have British Gas coming to install a Hive system which will allow us to set temperatures on a thermostat, and will hopefully help us avoid this yo-yo effect with the temperatures (and hopefully save us a few quid also, as we won't be heating unnecessarily and then having to sit with doors and windows open to cool down)

 

I have washed the affected walls and skirting boards today with a bleach solution, and to be honest it wasn't all that bad (nowhere near some of the horror stories that you come across in the media etc). I will see how the new thermostat works out and go from there - - one thing that is notable, the work I did in the kitchen yesterday seems to be doing the job as the floor don't feel as cold - - I seriously doubt that this is the reason for condensation at the French doors (too far away) but it may have been a source of moist air being dragged into the house?

I might be being a bit picky with this, but I feel that I have a responsibility to my landlady to do everything I can to eliminate this before I go bothering her with it. If I am not successful, then I have absolutely no doubt that she will get someone professional in (I am lucky to have a good landlady in this house).

 

And another discovery - the rubber seals on the French doors must be tired, as there is quite a significant draught blowing in even when they are locked shut, and certainly answers the fairly significant temperature difference in the area 6-8" from the door.

So, I will have to see if I can get new rubbers from somewhere

 

My son has this in his house, he wouldn't be without it now. He can adjust the temp on an app on his phone so it's warmed up when they get home.

 

Unless it is utterly baltic outside, we generally always have the back door open to ventilate the kitchen @WeeTam; more often than not, we also have a window open at the foot of the stairs as it lets a nice stream of fresh air into the living room and stairs.

Outside is a patio, which is set below the level that appears to be the DPC, no downpipe nearby and guttering is clear. The only thing that does happen occasionally is when it rains really hard and the wind is blowing in the right direction - the French doors have a sort of lip along the top that sticks out from the wall by about an inch and a half. The water collects on this lip and then pours off landing on the bottom sill of the French doors - - it immediately runs off the sill of course, onto the patio, so the only real symptom is a bit of noise as the larger blobs of water land on the bottom sill.

Interestingly, I noticed this morning that where the patio meets the house, underneath the bottom sill of the French doors, a fungi has appeared - it looks a bit similar to old semi-dried orange peel sitting up on end; whether that is an indication of anything or not I have no idea? Clearly, I need to re-point the patio when the weather improves.

 

Could be - I am wondering if I should point the gap between the house and the patio with a mastic rather than concrete. Wonder what the fungi is - maybe @Zigs would know?