Hello!

We have a one bed ground floor end of terrace flat.
Down one side there are obviously outside walls and we have a real problem with condensation and mould/mildew.

I had double glazing fitted 5 years ago and that has helped the condensation on the windows. In the bedroom we also have the airing cupboard so there is an obvious heat issue but could there be something wrong with this outside wall that we get so much condensation after the heating is on and if it's really cold outside?
I have small vents on the windows which I try to open asap but you feel like so much cold air is getting in then.......
Also I treated this wall with antimould stuff and even painted it with bathroom paint to help the issue or maybe not? It is terrible above the window itself in real droplets and the curtains are suffering with mould now!
In the lounge the mould has just grown back all along the skirting and on one side of the window frame. Incidentally, the windows run from wall to wall ie. there are no recesses.

Any advice please??

Many thanks

1. Photos, please.
2. Date of construction?
3. Type of construction? Stone? Brick? (if so what sort?) Concrete block? Other construction? Rendered or not?
4. Plastered on to the hard? Or lath and plaster? Or plasterboard?
5. Any insulation on the walls?

John

Thanks for your response!

I'll try and answer all points.......
1)Photos posted
2)Built in 1963 (ex council)
3)Brick built
4)Can't be sure but it is definitely plastered to the hard. Could be concrete block

5)I've wondered whether cavity wall insulation would help.......?

Anyway, hope that helps

Now we're getting somewhere!


Very helpful information


Again, useful information. How do you know? Is the brick visible, unrendered, on the outside?


That could well be the case. Two of your pictures show what could be early indications of efflorescence. Anyhow, it's easy enough to determine whether it's plastered on the hard. Bang the wall -- does it sound in any way hollow or do you end up with a very sore fist? . If it's plastered on the hard, there's part of the reason for your problem.


Yes, enormously, in all probability. Always assuming you're certain about the construction being brick and there being a cavity. In the 1960s Councils were doing all sorts of things, including using "No fines" concrete construction.
Failing cavity wall insulation, then insulation on the inside. It will cost you about 3" of your room space, but you'll have more usable space and no more cold walls.

John

Thank you again.

Yep the brick is visible on the outside of both the rooms, hence my brick built assumption. It is definitely a sore fist and no hollow sound plasterboard, so plastered to the hard.

Is there a way I can find out if cavity wall insulation would be possible? I would rather this than coming in to the room space if possible.

Also, is the probable bad insulation of my walls the reason for mould growing then?? Sorry if that's a silly question. The condensation is the real problem and the paint is obviously infected therefore the mould keeps growing back.......

OK, that's one point out of the road -- though we still don't know what the inner leaf is built with.

Typical council practice. Makes a very robust job, so can understand the logic.

If there's a cavity there -- and at that age you would certainly expect to find that -- it's possible. However it's a flat and there may be all sorts of legal questions with regard to ventilation of the inter-leaf space. And indeed the insulation spreading to other parts of the cavity that aren't yours. Others will know more about the legal position on this one, but I would have thought it's a bit of a minefield. And on a practical level, I doubt whether any commercial company is likely to be interested in doing such a small job. Yes, working inside is a bit of a guddle, but it's well worth it.

No question is silly when it's genuine. And as I understand it there are usually multiple reasons for mould developing, a few of which are
1. Damp atmosphere
2. Cold walls
3. Inadequate ventilation
4. Inadequate heating
5. Inadequate insulation
6. Existing mould spores

When you look at the solutions people often suggest you end up thinking "Some of these seem likely to work against each other -- e.g. how can you have more ventilation AND more warmth?.

I think you need to have a sensible look at the problem first and I would suggest that before doing anything else it might be an idea to consider

1. buying a hygrometer. It'll only cost a pound or two. They're often incorporated into cheap clocks sold by Lidl etc. What is the relative humidity in each of the rooms? If it's over80% you've got problems.

2. taking steps to cut down on sources of humidity, if the Relative Humidity is high (40% - 60% is OK). It's amazing how many people boil pans furiously with steam belching out and the lid off. You can buy standard-size lids with a steam vent in them (Google for glass saucepan lids) -- if those lids are pushing up you're using far too much heat -- turn it down! Drying laundry indoors is another source of excessive moisture

3. if the Relative Humidity is high, getting a dehumidifier -- that can pull gallons of water out of the atmosphere in a day

4. maintaining a steady heat in the rooms concerned. You need to get the WALLS up to temperature, too, and that takes many hours.

5. If there's a bath, ensuring that the hot water is not run before the cold, when filling it

6. You'll find plenty of advice on getting rid of existing mould spores. Personally, when tackling a particularly resistant mould outbreak in a windowless en suite I found that the best product was Dettol's Mould and Mildew Remover. But it's strong stuff!

That will give you a start. Apart from the dehumidifier, the capital cost of those steps is very low indeed and you will at least know, from the hygrometer, whether the Relative Humidity in each of your rooms is high or not. Try the hygrometer first and that will give you a start. Then, if it's giving high figures over a few hours in each of the rooms, think about the dehumidifier.

If eventually you go for an insulation project, consider whether you should be looking at your ceilings -- in a ground-floor flat you can expect that a very large proportion of your heating bill is being spent for the benefit of the people in the flat above you.

Condensation is caused when warm moist air meets a cold surface. The cooler air can't keep such a high amount of moisture, so the moisture condenses (turns into water)on the cold surface and of course provides a suitable breeding ground for mould.

John

Well! Many thanks. You certainly have given us a lot to think about and many options to consider.........

I have had a quick look at some internal wall insulation companies/products and you can get some as little as 10mm thick now, which is great. We also have to consider that we have pipes running along the problem wall (another contributor to the heat) and whether they can be worked around.

I think I will contact the council in the meantime and ask them the exact composition of the walls and whether anyone has had cavity wall insulating done.

Again thank you. I have used some polycell mould and mildew remover for now but will get some dettol if it's powerful stuff.

Bron

For cleaning the mildew just use a bleach / water mix, much cheaper than the branded products which are pretty much the same anyway!

As for your issues previous posters have given excellent advice on reducing the amount of condensation you create. Its interesting you note since the Double Glazing has been installed it has sorted the windows but made the rest worst, if you think logically about this the windows are now no longer the coldest external face in the house so the condensation goes elsewhere.

You'd be amazed at the difference a little ventilation will make, if your windows have trickle vents you really should leave these openly permamently, we have our bedroom windows open on the venting lock (don't know what you call it) all year round.

I would look at ventilation and reducing humidity before even thinking about insulation.

I tried in vain to get rid of persistent mould in a shower room using various types of ordinary bleach. The Dettol product, which contains both Sodium Hypochlorite and Sodium Hydroxide proved effective whereas ordinary bleach did not.

I have since heard that Polycell 3 in 1 Mould Killer, available from B & Q, is even better -- it's an ICI product and the active ingredients are BENZALKONIUM CHLORIDE and DISODIUM OCTABORATE. I can't vouch for it personally, but worth a try.

John