Help with my damp spot, please
Discussion
Hey all,
I've read a few damp spot threads recently with keen interest and it must be the time of year when these problems materialise.
With that in mind, I have a damp spot problem in my bathroom. I am really hoping someone can help me at least identifying which sort of tradesman I need to get in touch with to help diagnose the problem or maybe offer some diagnosis given my limited description.
The house is a 1900s miner's cottage at the end of a 10-house terrace. The main house is of a stone solid stone construction (lias stone) and the bathroom is an additional two-story construction built in the same style as the rest of the house. Half of the kitchen sits under the bathroom and the rest of the kitchen is an additional single-skinned and single storey extension built later than the rest of the house. The bathroom has a chimney stack but there are no visible pots or holes and there doesn't appear to be a chimney breast inside the bathroom or beneath it in the kitchen.
The bathroom is an oblong shape (2.4m X 3m), with the narrowest end joining it to the main house. The chimney stack is on the furthest away wall with a window in the back left-hand side of the bathroom. This is the only window in the bathroom. The roof was replaced fairly recently (in the last 5-years, done before we moved in) and the pointing and tiles all look fine and there's a felt layer underneath the tiles. The window was replaced earlier this year with a like-for-like double glazing unit but we specced a trickle vent that is always open. There's also an extractor fan that runs when the light is on and for ~5 minutes after the light has been turned off.
The damp problem is happening in the back left hand corner of the room on the ceiling and between the roof and wall (gable end - where the window and chimney is). The damp happens on both the longest wall and the end wall and looks like it originates from the top of the wall and then 'drips' downwards towards the floor.
Damp is present regardless of the outside weather but gets worse when it is either cold or wet. During this summer's long dry spell the damp spot decreased significantly but didn't dry out. This has led me to rule out it being a problem with the chimney stack, pointing, stonework or roof - ie there isn't a leak.
I run a dehumidifier underneath the damp spot 12 hours a day and it does a good job of drying out the night's damp. Take a shower and the damp spot will return instantly even with the window open, extractor fan on and dehumidifier running.
Note the darker spots of damp.
What on earth could the problem be? Any help is really appreciated!
I've read a few damp spot threads recently with keen interest and it must be the time of year when these problems materialise.
With that in mind, I have a damp spot problem in my bathroom. I am really hoping someone can help me at least identifying which sort of tradesman I need to get in touch with to help diagnose the problem or maybe offer some diagnosis given my limited description.
The house is a 1900s miner's cottage at the end of a 10-house terrace. The main house is of a stone solid stone construction (lias stone) and the bathroom is an additional two-story construction built in the same style as the rest of the house. Half of the kitchen sits under the bathroom and the rest of the kitchen is an additional single-skinned and single storey extension built later than the rest of the house. The bathroom has a chimney stack but there are no visible pots or holes and there doesn't appear to be a chimney breast inside the bathroom or beneath it in the kitchen.
The bathroom is an oblong shape (2.4m X 3m), with the narrowest end joining it to the main house. The chimney stack is on the furthest away wall with a window in the back left-hand side of the bathroom. This is the only window in the bathroom. The roof was replaced fairly recently (in the last 5-years, done before we moved in) and the pointing and tiles all look fine and there's a felt layer underneath the tiles. The window was replaced earlier this year with a like-for-like double glazing unit but we specced a trickle vent that is always open. There's also an extractor fan that runs when the light is on and for ~5 minutes after the light has been turned off.
The damp problem is happening in the back left hand corner of the room on the ceiling and between the roof and wall (gable end - where the window and chimney is). The damp happens on both the longest wall and the end wall and looks like it originates from the top of the wall and then 'drips' downwards towards the floor.
Damp is present regardless of the outside weather but gets worse when it is either cold or wet. During this summer's long dry spell the damp spot decreased significantly but didn't dry out. This has led me to rule out it being a problem with the chimney stack, pointing, stonework or roof - ie there isn't a leak.
I run a dehumidifier underneath the damp spot 12 hours a day and it does a good job of drying out the night's damp. Take a shower and the damp spot will return instantly even with the window open, extractor fan on and dehumidifier running.
Note the darker spots of damp.
What on earth could the problem be? Any help is really appreciated!
SpeckledJim said:
No expert but are those roof tiles fitted with the correct overlap?
Looks like the shapes on the sides are designed to be ~4 inches closer together?
The last row is only overlapped by an inch, is that correct?
Yeah, I originally thought that but there's quite a bit more tile underneath and that lack of overlap is only along the edge where water *shouldn't* be running...Looks like the shapes on the sides are designed to be ~4 inches closer together?
The last row is only overlapped by an inch, is that correct?
BackPedal said:
SpeckledJim said:
No expert but are those roof tiles fitted with the correct overlap?
Looks like the shapes on the sides are designed to be ~4 inches closer together?
The last row is only overlapped by an inch, is that correct?
Yeah, I originally thought that but there's quite a bit more tile underneath and that lack of overlap is only along the edge where water *shouldn't* be running...Looks like the shapes on the sides are designed to be ~4 inches closer together?
The last row is only overlapped by an inch, is that correct?
Out of interest where does your extractor fan exit to, I'm assuming its that grey mushroom thing however i have been in the ventilation industry for some years I've not seen that before at the very least it should have either a cowl, flaps or a grill.
https://www.domusventilation.co.uk/ventilation-sol...
https://www.domusventilation.co.uk/ventilation-sol...
SpeckledJim said:
Hmm, that's not as bad as I thought, but its still very different to the other side of your roof.
Yarp, the roof isn't symmetrical.The reason I think it's a damp spot is that rain doesn't make it worse and a lack of rain doesn't make it better. For example, if we were to take no showers or use the bathroom at all for a few days but it rains buckets, the damp patch does start to fade slightly. I happens as soon as we create steam, humidity and heat in the room.
-Edited for accuracy of roof tile count!
Edited by BackPedal on Friday 9th November 15:59
wilksy61 said:
Out of interest where does your extractor fan exit to, I'm assuming its that grey mushroom thing however i have been in the ventilation industry for some years I've not seen that before at the very least it should have either a cowl, flaps or a grill.
https://www.domusventilation.co.uk/ventilation-sol...
Yes, it goes into the mushroom thingy. It looks kind of like a bell housing?https://www.domusventilation.co.uk/ventilation-sol...
The top of it siliconed against the wall but the bottom is open and air is free to circulate.
I would suggest that you are getting very little airflow through that as the resistance will be quite high even over such a short run, also is the fan ducted through the wall with pipe or has somebody used flexi pipe .
Probably nothing to do with your issue however if it is present after a shower/bath then something is definitely damp
Probably nothing to do with your issue however if it is present after a shower/bath then something is definitely damp
It could do as you say its returns instantly after a bath as it has probably never dried out, never underestimate moist air - in most builds people use flexi pipe to extract from bathrooms going into the loft space and then outside. This should really have a condensation trap fitted as the cold loft air will condense with the warm moist air from a bathroom, I designed the one that Domus sell but they are very rarely used.
wilksy61 said:
I would suggest that you are getting very little airflow through that as the resistance will be quite high even over such a short run, also is the fan ducted through the wall with pipe or has somebody used flexi pipe .
Probably nothing to do with your issue however if it is present after a shower/bath then something is definitely damp
Not sure, I'll check tomorrow - but thanks for the suggestion.Probably nothing to do with your issue however if it is present after a shower/bath then something is definitely damp
wilksy61 said:
As a side thought running a dehumidifier with a window open will make the unit run a lot harder as it will basically draw air in from outside, you really should close windows when using one.
Yeah, I don't run the dehumidifier with the window open, just the trickle vent remains open.Edited by BackPedal on Friday 9th November 16:19
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