Cold, condensation and mould.....

I like to think that I am reasonably practical when it comes to home maintenance and DIY, but I have a bit of a problem that I can't quite work out how best to resolve.

Here is a rough floorplan of the ground floor (minus the porch and front door) of our house: -


The square area on the left is our main sitting area, and the rectangular area next to the kitchen leads down to a set of double glazed French doors - on each side heading down to the French doors, we have sideboards.

The two brown rectangles are central heating radiators.

Now, in short, my problem is black mould on the lower 12" of the walls and skirting boards in the reveals of the French doors (red circles on drawing), and it creeps round from the reveals onto the inside of the walls. The room is kept warm, and is ventilated also (as it the rest of the house). Summer before last, I redecorated the whole house and took a lot of time to clean and treat these problem walls with suitable mould treatment which I then allowed to dry thoroughly and then painted - at the time, our discovered that our dishwasher had been leaking on the other side of the wall, so arrived at the conclusion that it was that dampness that had caused the problem, and as I had repaired the leak, dried things out and treated the area where the mould was, I reckoned all would be well.

Wrong.

This winter, the mould is back with a vengeance, and I am going to have to sort it all out and redecorate once more - however, this time I want to sort the problem for once and for all.

I have been monitoring things for a few weeks to see if I can understand why we are getting mould in the area we are, and it turns out that it is pretty simple -- when it is cold outdoors, there is a pall of cold air that hangs by the French doors; step back from the doors by a foot, and the room is nice and warm - it is simply that the floor and walls around the doors is so cold, and the heat in the room doesn't seem to get right down to the doors - hence condensation is forming on the cold surfaces and giving mould the ideal conditions to take hold.

So, it seems clear to me that I need to try and get some local heat sorted out, but I have no idea how to heat such a small area. If the reveals of the door were deeper, then I suppose and air curtain heater might be the best option, but there is simply no room for one of those (not to mention that they are gutsy blighters on the old electric!); I don't need a lot of heat either - just enough to take the chill off the area around the walls of the reveals.

In some respects, a couple of those tubular heaters (60 to 100w or so) would be sufficient in terms of heat output, but I think they would look really odd?

The only other thing I can think of is some sort of heat pad under the carpet, but would one of those put out sufficient heat?

All suggestions considered, so please fire away ladies and gents

 

I'm starting to lean back toward the tubular heaters, not least because they are less than £20 a go, and the two foot ones only use 80w each - I just worry that they will look really odd being mounted vertically

 

Nah, that idea is a dead duck too - the tubular heaters cannot be mounted vertically.

 

I must admit, the amount of heat in the room isn't an issue, but I cannot for the life of me think of a way to improve circulation around those corners. The sideboards that are are on either side on the way down to the French doors are the sort up on four legs (so the air can flow under them) and they are not sat against any of the walls - I deliberately left space around them to allow air to circulate.

The floors are all concrete, and the underlay isn't the best, which I suspect isn't helping, but for the lack of a way to circulate the air, I thought some heat to prevent condensation would be the way to go. Trouble is, we rent so there are limits as to what I can do, and limits as to what I am willing to do to resolve this. If I owned the house, the entire bottom floor would be lifted and underfloor heating would be installed (ran off the CH system) - but there is no way I am going to that sort of cost in a renter.

As far as I am aware, yes there is. The exterior walls are all very cold - in fact, the entire back wall of the house has absolutely no heat whatsoever; in the kitchen (unheated) there was one hell of a draught coming under the kickboards under the cupboards, so much so you could feel it freezing the ends of your toes if you were standing at the cooker etc.

I had the kickboards off, and put a load of insulation underneath the cupboards - - I just used wads of loft insulation, so it can be hauled out in seconds if needs be, but that seems to have helped that draught quite a bit. On really cold nights, we have a lined curtain that we pull over to cover the doorway between the living room and the kitchen (there is no door), and that keeps the heat in the living room and keeps us cosy. For next winter, I am planning on getting an electric flat panel radiator (the plug in kind) which I will mount on the wee bit of spare wall in the kitchen to take the chill off the place - I am not looking for it to be warm as such, but it being currently unheated means that it can draw heat out of the living room.

The two central heating rads have quite a job on their hands as well (which probably doesn't help the air flow), as they have to heat the entire bottom floor and the staircase (open plan) up to the top landing. On the upper floor, the heating is only really adequate/effective in one room and that is the back bedroom - - the front struggles as it is only a small, single panel fellow and the bathroom has a chrome heated towel rail (warms towels, but doesn't give off much heat into the room)

 

No idea where I could put a vent - the French doors are almost the full width of the back part of the living room. I might be able to squeeze one in on one side of the doors, depending on how wide it would need to be?

I take it that I would have to get some sort of hole cutter and an SDS to make a vent through the two skins?

 

I'm not sure that a vent, even at a low height, is one for me to tackle - at least, not without speaking to the landlady. I am not overly comfortable at the thought of knocking a hole in her wall without her knowledge.......

If I could find a way of pushing air over the surfaces pretty much continually, would that help @Zigs?

I am wondering if I could construct something (box with fans to draw air in, then a ducting to bring the air out at floor level, pointing directly at the walls)? After all, I would only have to run them in winter?

 

Yes, it is cavity wall insulated with the exception of the front bedroom front wall - the front of the house is wooden clad on the upper half, and they wouldn't drill through the cladding to blow the insulation in.

The issue with these wee corners was already notable before the insulation, but I agree that it is possibly being made worse now due to the lack of cold surfaces.