Redecorating condensation problem wall

cyclonebri1

redgie wrote: »

I feel for you dorsetlady, it sounds like you've done everything right, I hope you manage to crack it

myhooose, I didn't realise you could use the anti-mould additive in wallpaper paste and polyfiller, that does increase my options, thank you.

Thanks cyclonebri1, what would you use to bond polystyrene to wall? Would you use a layer of adhesive between polystyrene and plasterboard as well?

I'd use "No more nails", or a similar trade named product, but beware do not use anything that is solvent based as it will "eat" polystyrene. (no more nails is available in solvent based or non solvent).

I wouldn't glue the board to the poly as you want maximum contact.

Thinking again possibly the best and easiest option would be to screw battens to the wall the same thickness as the poly in which case you wouldn't even need any adhesive. Then use drywall screws to fix the PB sheets. ;)

budgetdiyer

I would opt for the following solution if it were me:

1) Install an airvent (sleeved through the cavity) - These are best placed high on the wall, if one corner seems more affected put it in that corner.

2) Batten the wall and add slabbed 'cavity' wall insulation between the battens, then fix layer of plasterboard over the top. (i wouldn't use polystrene, its not a very good insulator)

A couple of other questions for you, are the windows double glazed? What type of heating do you have in the room?

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Dorset Lady, you should be able to find a way to eliminate the condensation completely or at least to a very manageable level. It is possible to over ventilate a room, have you got vents installed or just use the window to ventilate?

Have you tried using a dehumidifier? How much moisture are you getting out daily?

jozbo

cyclonebri1 wrote: »

I'd use "No more nails", or a similar trade named product, but beware do not use anything that is solvent based as it will "eat" polystyrene. (no more nails is available in solvent based or non solvent).

I wouldn't glue the board to the poly as you want maximum contact.

Thinking again possibly the best and easiest option would be to screw battens to the wall the same thickness as the poly in which case you wouldn't even need any adhesive. Then use drywall screws to fix the PB sheets. ;)

That's useful advice - so is insulating behind the plasterboard going to prevent further mould growth long term? the mould won't grow behind it?

Sorry trying to get my head around how to fix it in our place, we are fully redecorating so want to get it right first time

cyclonebri1

Mould grows where moist warm air hits a cold surface over a longterm.

Break the chain in 2 steps,

Insulate the wall and you have eliminated, or likely reduced the cold surface.

Only way to eliminate the moist air is to ventilate, that's pretty much cast in stone.;);)

redgie

budgetdiyer - windows are double glazed (no trickle vent), house is central heated, single panel radiator is placed beneath window.

I know we need more ventilation - hoping to get extractors in bathroom and kitchen next year as well as sleeve vent - until then we'll have to leave windows open and doors closed. We have a condenser tumble dryer which we are moving to a shed as we think this is a major culprit, we have a dehumidifier.

Like jozbo I am worried about mould growing behind any new plasterboard we install as I can't see how we can make it completely airtight. Wondering if I should paint everything with anti-mould paint before installation - maybe OTT, but am worried about having the same problem as dorsetlady and having to rip it all out again next year.

Have lost count of the number of times I've changed my mind on what to do with this room

cyclonebri1

use aluminium foil backed board and seal with a polyurethane sealer in the joints and rounds the edges.

Add that to the advice/opinion I posted earlier. ;)

Spiggle

FWIW, my experience with a cold room with condensation and black mould.

It's a bedroom on the north corner of detached bungalow with quite large double glazed bay window. Largest wall is due north facing and has a west facing wall with bay window (returns to northwest). Has always been the cold room in the house which I thought would resolve when we originally had central heating fitted in '88. It didn't and the room always felt 'detatched' from the rest of the house - always cold and damp feeling. Always had creeping mould on north outside wall and under the windows down to (or up from) mouldy skirtings.

A few years ago I thought I'd resolve my issues by stripping back, treating with mould suppressant and lining walls with warmaline before papering over with thick high quality lining paper (both adhesives used had fungicide in them) and painting. This did improve the mould situation but did nothing to help with the the morgue like atmosphere.

Last year when researching a new rad when refurbing my bathroom, I looked at btu output calculators. The radiator fitted in '88, a universal single panel, was capable of less than half the output the room size required. Bought a new one of suitable capacity and had that fitted when the heating engineer fitted the bathroom one.

For the first time in 24 years the bedroom is a part of the house. I never shiver as I go in there. The atmosphere is dry (but not so much it sets off my asthma). And last week when the weather was glorious I had the novel experience of being too warm in the evening in that room due to the heat from the suns rays through the windows and the insulating properties of the room.

I have my windows open throughout the year but at varying amounts dependent upon the weather conditions.

Hope that may help you in some way. It never struck me that the radiator may be under capacity. It fitted where it was to go which I think was the deciding factor in '88 rather than the required uotput. If I hadn't stumbled across the btu calculator that room would still be horrid.

All the best,
Spigs

budgetdiyer

redgie wrote: »

budgetdiyer - windows are double glazed (no trickle vent), house is central heated, single panel radiator is placed beneath window.

I know we need more ventilation - hoping to get extractors in bathroom and kitchen next year as well as sleeve vent - until then we'll have to leave windows open and doors closed. We have a condenser tumble dryer which we are moving to a shed as we think this is a major culprit, we have a dehumidifier.

I think with a conventional construction house with central heating it should be entirely possible to eliminate condensation completely. You can't really compare solutions from other members are their property construction / layout could be very different.

I have condensation in my bathroom, and porch (the bathroom window vents into the porch - its a great design which along with the questionable construction of the porch creates the condensation in there!) - I have an extractor fan on the todo list!

I would suggest go down the batten / insulate / plasterboard route and seriously consider your other suggestions to minimise / remove the condensation you generate.

cyclonebri1

Spiggle wrote: »

FWIW, my experience with a cold room with condensation and black mould.

It's a bedroom on the north corner of detached bungalow with quite large double glazed bay window
I have my windows open throughout the year but at varying

All the best,
Spigs

Spigs, my experience is based on exactly your situation bungalow wise, 1930 style bungalows with a bedroom in two corners are notorious for the problem. Probably because you have a cold floor 2 cold walls and a cold ceiling, not heat from above as ther is in a 2 storey building.
I compounded the issue by installing fitted wardrobes on the outside walls, we had huge problems with mould behind the units and that musty smell that you can't mistake.

I eventually had to take the whole lot out in both bedrooms and put 2" slab polystyrene on all the outside walls before I refitted the units. Even filled the void behind the plinths.

That and a little more ventilation did the trick. ;)