Damp circles on outer wall in ensuite

millsy5 · Post by **millsy5** » Mon Jan 16, 2023 2:05 pm

I'm living in a new build (A rated) for just over 4 years. I've noticed for maybe the last year that damp patches have formed on the outer wall in the ensuite. All other rooms are fine.

: Ensuite; Ensuite.jpg (63.37 KiB) Viewed 2417 times

The first ones to appear were the two directly above the window, on flat horizontal part of the window 'cutout' (not sure the proper name for this). These are exactly symmetrical with each other which is unusual.

: Top left of window; Damp above window left.jpg (51.74 KiB) Viewed 2417 times

: Top right of window; Damp above window right.jpg (59.3 KiB) Viewed 2417 times

Then more recently (some time after the summer) additional ones started appearing on the wall above the window, as well as an additional one right next to the extractor.

: Damp patches on wall above window; Damp above window.jpg (22 KiB) Viewed 2417 times

The outer wall has insulated plasterboard on the inside of the block.

The damp is worse after I have a shower in there.

I'm not sure if it's a ventilation issue as the extractor comes on with the light (I always ensure it is on regardless of whether I need the light on or not). Also the extractor itself provides ventilation even when off.

I usually have the window open during the day, until it's really cold out.

Any thoughts on the cause of these damp patches, and whether some damage might already be done inside the wall? I don't work in the building trade so don't really have a clue about this.

: Top left of window; Damp above window left.jpg (51.74 KiB) Viewed 2417 times

aeromech3 · Post by **aeromech3** » Mon Jan 16, 2023 2:15 pm

At a guess some sort of bridging is occurring, that is a solid is making a bridge between outside cold wall and the inside, not much you can do easily about that more than you are by ventilation.
As the patches are high up, are there any external wetting caused by blocked guttering etc?

millsy5 · Post by **millsy5** » Mon Jan 16, 2023 4:16 pm

No gutter on gable end of the house where the ensuite is. Everything looks fine to me I think.

: Outside; 20230116_160528.jpg (86.62 KiB) Viewed 2407 times

Not sure why photo is rotated when I upload it.

toolbox · Post by **toolbox** » Mon Jan 16, 2023 4:27 pm

Might try a pipe finder or strong magnet if you get metal it might be water tracking along a wall tie. Any cavity insulation?

arco_iris · Post by **arco_iris** » Mon Jan 16, 2023 9:24 pm

: 20230116_160528~2.jpg (48.37 KiB) Viewed 2402 times

millsy5 · Post by **millsy5** » Tue Jan 17, 2023 10:09 am

toolbox wrote: ↑Mon Jan 16, 2023 4:27 pm Might try a pipe finder or strong magnet if you get metal it might be water tracking along a wall tie. Any cavity insulation?

From inside to outside there is: insulated plasterboard (40mm insulation), block, insulation, block

toolbox · Post by **toolbox** » Tue Jan 17, 2023 12:42 pm

With 40mm of board I doubt my idea will work then.

millsy5 · Post by **millsy5** » Tue Jan 17, 2023 1:19 pm

Is this issue something the builder should look at? I'm only in the house 4 years. Even though I know he will try to blame me for the lack of ventilation (e.g. not opening window).

Do you know if Homebond do a moisure check on the walls? I recall the guy fitting the kitchen telling me that the walls were moist (he told me this after I asked his advice on mounting a TV bracket on the wall as I've never hung something off a wall with insulation on the outside of the block). He said he thinks maybe the house was built too quickly and possilby required longer time to dry out. I said this to the builder who said Homebond signed off the house so there were no issues.

millsy5 · Post by **millsy5** » Wed Jan 18, 2023 3:56 pm

I just ran a magnet over the wall. It only stuck on the damp patches indicating that there are screws here.

millsy5 · Post by **millsy5** » Thu Jan 19, 2023 2:48 pm

Or ties too I suppose

aeromech3 · Post by **aeromech3** » Thu Jan 19, 2023 2:53 pm

That indeed points to the problem of bridging, I think you are in a corner with this, keep ventilated and occasion wipe with diluted bleach or vinegar sponge to stop mildew forming.

millsy5 · Post by **millsy5** » Fri Jan 20, 2023 9:38 am

Mould has formed in the past. I've had to spray with Cillit Bang Black Mould Remover to get rid of it.

I wonder if the fan isn't powerful enough to remove the steam from the shower? And installation a better one might help?

aeromech3 · Post by **aeromech3** » Fri Jan 20, 2023 2:49 pm

Without the fan the corners would show mould, yours is in specific areas and you have identified metal, are there other areas with same metal on outer wall, that are not damp?
A more powerful extractor needs more free air movement into the bathroom do you have this; in my overseas property, I have a mean size extractor fan, it will pull closed the adjacent bedroom hardwood door unless a window is opened; yet after 7 years it too has a mild mould on the corners of the ceiling and quite near the extractor but general humidity and temperatures are way above UK.

millsy5 · Post by **millsy5** » Sun Jan 22, 2023 7:24 pm

aeromech3 wrote: ↑Fri Jan 20, 2023 2:49 pm Without the fan the corners would show mould, yours is in specific areas and you have identified metal, are there other areas with same metal on outer wall, that are not damp?

I think only the areas with metal have damp. I'm not aware of any of metal that isn't getting damp. The walls around the bathroom are stud partition walls.