How to deal with black mould on walls.

[richiep]

Hi all,

I'm wanting to tile my bathroom walls, but there are large amounts of black mould growing over the paint. I know the paint will need to be removed before i tile, but how big a problem is the mould?

I can wipe most surface mould off with tissue but is this mould in the plaster and will the walls need re-plastering? Or is there a way i can deal with this to enable me to tile over?

What i don't want is to tile the walls then find them popping off due to damp.

All advice would be grateful please.

Rich

 

[Gazzer]

Where is the mould coming from 1st ? No good cleaning it of and tiling if its coming through from somewhere else.

 

[diamondtiling]

Is there any ventilation in the bathroom, as in a wall vent?

If not then it wont help, as Sir Ramic says you need to find the cause.

 

[richiep]

There is no wall vent or extractor fan, just a window we open to air the room. The walls that have the mould are the exterior walls if that makes sense, ie, no room on the other side, just the exterior of the house. We have only this year had the walls insulated, had insulation blown in.

 

[Gazzer]

If you are happy that the mould is coming from being used as bathroom without ventilation then firstly I would install some sort of extractor fan for the future. The mould could be dealt with by cleaning down with bleach. I believe this will kill the mould spores.

 

[diamondtiling]

Insulation blown into the cavity? How old is the house?

Bricks get wet in the rain and dry out naturally, similar to grout. With the pumped in insulation the air cavity has gone and damp has no where to go so it is drawn to the driest area which will be the inner wall.
Dont confuse this with slabbed insulation that is fixed to the blockwork, at least with that system there is still an airway.

 

[Mouldy]

Blown insulation. One of the worst inventions ever I think........

 

[richiep]

If you are happy that the mould is coming from being used as bathroom without ventilation then firstly I would install some sort of extractor fan for the future. The mould could be dealt with by cleaning down with bleach. I believe this will kill the mould spores.

Thanks, i will try the bleach to see if it has an effect. Think the extractor fan is the way forward too. Much appreciated.

 

[2020Tiling]

could just be condesation ! have you a decent size radiator in the room ? as you need heat and ventalation to cure condensation. you could use bleach to get rid of the mold then use a diuhumidifier the take the moisture from the walls.

 

[Mouldy]

YOu could also try this:-

Zinsser UK - Perma-White (Interior) or this;

Zinsser UK - Bulls Eye 1-2-3

 

[dilz000]

can that stuff be tiled over mouldy?

 

[White Room]

I would'nt, the mould would probably creep thru to the grout

 

[dilz000]

ive never seen it before thats all. how about tanking?

 

[Scott]

The bleach wont kill the mould completely and it will come back. If you have a shower then its building regs to have extraction in the room anyway. As for cavity wall insulation, did you have the mould before?

Id be suprised if the mould would penetrate the grout joints as i have tiled some pretty minging bathrooms and its not happened yet.

 

[Qwerty]

I agree Scottley.... any mould would just set up a new home on top of new grout/ tiles if ventilation not sorted. Spores would not develop or penetrate through new grout

 

[faithhealer]

HG mould cleaner is excellent for removing mould but definitely need air movement

 

[doug boardley]

It is good stuff Faith, but as others have suggested, extractor fan is needed.

 

[jay]

external walls are only ones effected by mould this must indicate something that needs sorting first

 

[Deleted member 9966]

do you guys think that the cavity wall insulation could have started the problems here in this situation then?

I've been toying with the idea of cavity wall insulation in my house but I won't bother if it will start creating damp and mould.

 

[jay]

hard to say without seeing but sounds as if in this case there is an issue that needs attention cavity walls are fine if the outside wall is waterproof same goes with solid walls the aim is to keep moisture out on the outside not try to stop it on the inside

take care

jay

 

[Gazzer]

When did the mould 1st appear ? After the insulation or before? Is it in just one area ?

 

[Mouldy]

can that stuff be tiled over mouldy?

I see no reason why not, however as has been said by others you need to rectify the reasons for the mould being there in the first place.

 

[thomas]

use a sander first on the mould then scrub with bleach,install an extractor fan that comes on with light switch and also an air vent on your window wall if possible,that always solved some scary bathrooms in the past.

 

[Gazzer]

How to Kill & Remove Mold with Bleach, Borax, Vinegar, Ammonia

 

[Scott]

The mould grows more on the external walls as they are slower to dry out as they tend to be cooler.

GRR dont worry too much about the damp from cavity insulation. The 'bridging' of a cavity is not that common a problem. Have a read up on google. Id have it installed as the saving in bills can be huge

 

[DHTiling]

do you guys think that the cavity wall insulation could have started the problems here in this situation then?

I've been toying with the idea of cavity wall insulation in my house but I won't bother if it will start creating damp and mould.

You have a new house Liz... your cavity walls should already be insulated..?

 

[Mouldy]

Scottley, our bugalow is cavity insulated and we have all sorts of issues now, although not al can be attributed to this. Looking to install HVHR to cure the problems.....

 

[Deleted member 9966]

You have a new house Liz... your cavity walls should already be insulated..?

Daveeeeeeee, it was built by Barratts! apparently they didn't spec any dpm over the concrete ground floors yet all houses on the estate have them. so I wouldn't be surprised if they had no cavity insulation. I'll ring Barratts and ask them how they built it. :lol:

 

[DHTiling]

It would be regs to do it Liz..

 

[Scott]

Doesnt mean it was done though! You can get a liquid DPM to put down if it wasnt.


Mouldy, did you have the insulation put in?

 

[Mouldy]

Yeah, blown insulation mate. I know new builds dont use full fill and I have no real problem with that. To me however the cavity is there for a reason and it aint to fill it!!!