Bathroom Walls Problems!

Ikeepgettingfines

Hi,

My bathroom, which has not been renovated by the previous owner for decades, in a 1950s house, has two of its wall always wet/moist with droplets of water dripping constantly.  This happens in Winter (and it has started already with the drop in temperature).  The two walls are North and East Facing and the face directly outside (i.e no further room/building).

At first, I thought the moisture was there because of the shower.  But I monitored last Winter and I could see that the walls remained moist even if the window is left open and even if there is no one using the shower.  This issue if moisture has caused a lot of damp and mould on the wall and ceiling of the bathroom.

​I am getting the bathroom refurbished and I would like to tackle this issue of the wall in one go.  Can you please advise the best way forward?

I plan to have all the walls tiled, and install a good extractor fan (fan recommendations will be helpful).

Do I install Moisture resistant plasterboard before tiling?  If not that, is it thermal plaster? or some sort of membrane to keep the wall warm and avoid moisture?  I'm worried that if it is tiled over, the moisture will come back and cause the tiles to break off over time.

It is worth noting that downstairs, I have my kitchen which also has similar problems of two walls having moisture in Winter.  This has caused damage to my kitchen cabinets too.  Leaving windows open helps but not much and it also becomes impractical during Winter.  I also have a dehumidifier which is sort of a band-aid temporary solution.  The windows in bedrooms also become quite dewy (moisture) overnight.

​I want a fixed long term solution to this very annoying and damaging problem.

Thank you for reading, I appreciate your help and guidance on this.

stuart45

You need to find the source of the problems first. It's possible that there's some penetrating damp coming through the walls, or roof at the eaves. It could be condensation alone, or maybe a combination of penetrating damp and condensation. Damp walls are colder than dry ones and so attract even more condensation.

ButterCheese

As above - you could use the best materials known to man but it would all be a waste if the water is getting in somewhere.  Don't just get any old builder in either; make sure it's someone your friends or family know and have been using for years.  We nearly got caught out by some "trusted" traders who quoted us 6 grand for a new flat roof, new front cladding and lead flashing.  We then got next door's brother in, who said none of that was needed and then in fact he found a few broken tiles.  In the end we got the whole job done for £1k

Emmia

If you want to install an extractor (once you've identified the cause of the wetness) then I'd get one with a humidistat which will run taking out excess moisture for as long as it needs to / when it needs to. 

Lots of options available, we have a vent axia one which is effective and pretty quiet in a windowless shower room

https://www.screwfix.com/p/vent-axia-477436b-100mm-4-axial-bathroom-extractor-fan-with-humidistat-timer-white-240v/922gy

ThisIsWeird

Photos, IKGF? And, during the wet spells we've had this year during Summer, was there a problem then? Does it only occur when the temperature drops?

Assuming it isn't penetrating moisture - coming from outside - then it'll almost certainly be condensation. So, the solution will be to add insulation to these exterior walls, and then consider covering them with a good quality wall board, one that'll add even more insulation; tiles don't.

FreeBear

Ikeepgettingfines said: ​I am getting the bathroom refurbished and I would like to tackle this issue of the wall in one go.  Can you please advise the best way forward?

I plan to have all the walls tiled, and install a good extractor fan (fan recommendations will be helpful).

Do I install Moisture resistant plasterboard before tiling?  If not that, is it thermal plaster? or some sort of membrane to keep the wall warm and avoid moisture?  I'm worried that if it is tiled over, the moisture will come back and cause the tiles to break off over time

Do not use plasterboard, even moisture resistant stuff on the walls. I would recommend something like Marmox tile backer boards (other brands available). These have an insulating core which will reduce the amount of condensation forming on the walls. Go for thicker boards - Minimum of 25mm, 50mm would be better. Cover the north and east facing walls from floor to ceiling and put some round the window reveals (you may only get away with 12-15mm in that area).

Internal walls can be covered in thinner Marmox boards - If you strip off the old plaster back to brick (more likely timber stud), 12mm can be used. Moisture resistant plasterboard can then go on the ceiling. If you take the ceiling down, it gives you the opportunity to move cables around and pack loft insulation between the joists right up to the perimeter of the room.

koalakoala

Are the rooms warm enough?

Ikeepgettingfines

Thank you for the replies.  The walls has been stripped down to bricks.  There's no sign of wet/damp bricks due to external factors.  It seems as most of your suggested, due to internal condensation.  I have purchased thermal plasterboard and will be installing these on the bricks.  Moisture boards will be placed on the internal facing walls.  I will then be adding XPS boards +Mapei Shower kit on the wet areas (around the bath tub).   then tiling with rapid set adhesive. 

Finally, I will install an inline extractor fan in the ceiling near the shower area.  And the plan is to also replace the old meta window with a double glazed aluminium one.

Doozergirl

The main culprit will be the lack of insulation.  A 1950s house would have none.  Please install as much as you can, bearing in mind that the current regulations dictate something like 100mm of kingspan type solid insulation and 150mm of rockwool for the walls, more for the roof. You also won't get the opportunity to do it again for many, many years, so do not scrimp on it!

Then your decent extraction and you'll be good. 

FreeBear

Doozergirl said:

The main culprit will be the lack of insulation.  A 1950s house would have none.  Please install as much as you can, bearing in mind that the current regulations dictate something like 100mm of kingspan type solid insulation and 150mm of rockwool for the walls, more for the roof. You also won't get the opportunity to do it again for many, many years, so do not scrimp on it!

65mm of Celotex/Kingspan will get you under 0.30 W/m²K which would satisfy building regs for a refurbishment. Polystyrene boards would need to be ~110mm thick for the same level of insulation.

If you're tiling, I'd go for multiple layers of Celotex (foamed & taped joints), and then 12mm Marmox tile backing boards. Gypsum plasters don't do well if constantly damp... But if you've already splashed out on materials, use what you've got.

Ikeepgettingfines

The walls and floor were stripped completely.

Due to having a solid brick wall which meant that the internal walls were very cold in Winter, I decided to put 37.5mm thermal plasterboard on the brick walls.

Now, I need to waterproof the walls, especially the one around the bathtub.

I am thinking:

6mm Jackoboard glued with Jackoboard Board Fix Adhesive on the thermal plasterboard. And then use Mapei Showerproofing kit (membrane) all across the bath tub on the Jackoboard. And then finally, porcelain tile will be glued onto the Jackoboard with cement base flexible adhesive.

I understand this will add an extra 6mm on the current 37.5mm thermal plasterboard + tiles + membrane + adhesive. But I want to make sure this is the right way forward?

Or do I just go with the following plan:

37.5mm Thermal Plasterboard, then Mapei Showerproofit Kit membrane + Tiles glued with rapid set tile adhesive?

The whole bathroom floor is being done as such: Joists, then moisture resistant chipboard, then NoMorePly 10mm XPS Backerboard, then Mapei Showerproofit membrane, then Ditramat, then Tile adhesive and then tiles.

Thank you for all your advice.