Damp patch mystery on ceiling

[dancubas]

I have what looks like a bad damp patch on my ceiling. But it is completely dry to the touch. Backstory:

This room is directly under the loft. I bought this house back in february, there was a wet patch in this spot caused by a leak coming from the gutter. I had that fixed, and also had the entire room re-plastered because it needed it. Once the plaster dried, I waited a good couple of months for the patch to dry before painting the ceiling, but the patch did not disappear. It wasn't wet to the touch, so I thought it was dry but may have just stained the plaster. I only applied a thin layer of paint to the area to see what would happen.

However since then, this patch has *very* slowly expanded, and I'm not sure what to do with it now. There is no sign of wetness directly above it or anywhere up in the loft, there is no water leaking in from anywhere.

So, could this be:
- trapped water somewhere under the insulation in the loft, that's been there for ages?
- the paint sealing in the water and not allowing it to dry, so it has to spread sideways?
- just a slowly spreading stain that I should use stain-cover on and forget about?

I've read that drilling a hole in the ceiling and allowing moisture to come out that way is a potential solution, but other than that, I'm stuck and would welcome any advice you may have. Many thanks!

 

[Burnerman]

Don't drill the ceiling, but get back into the loft and shift the insulation over the spot, checking to feel if it's wet.
Obviously water can run down timbers or whatever so the problem needn't be directly above the stain.
Are you sure it was a gutter problem originally causing this?
John

 

[dancubas]

Don't drill the ceiling, but get back into the loft and shift the insulation over the spot, checking to feel if it's wet.
Obviously water can run down timbers or whatever so the problem needn't be directly above the stain.
Are you sure it was a gutter problem originally causing this?
John

Thanks John, I have just been up in the loft to double check around the whole area, I've lifted up the insulation material and it's all dry, the rafters are all dry, the area under the insulation is all dry. There is nothing else there, just the roof tiles and the lining under them, all dry. I go up there occasionally to see whether any water is coming in when it rains, but it's always dry.

As to whether it was a gutter problem, I'm not 100% sure but the insulation material up there was wet when I bought the house, and when the gutter got fixed, it dried out, so I'm assuming it must have been that. Like I mentioned the patch is not wet to the touch, if there was water leaking in there all the time, I'm sure it would feel damp.

 

[Burnerman]

In which case I'd paint it over with a stain blocking paint such as Zinsser and see how things go.
Plaster doesn't like getting wet but there doesn't seem to be any bubbling there.
John

 

[dancubas]

In which case I'd paint it over with a stain blocking paint such as Zinsser and see how things go.
Plaster doesn't like getting wet but there doesn't seem to be any bubbling there.
John

Thanks again - do you think there's any danger of water being trapped up there between the joists and the ceiling? You're right about the bubbling, I'm sure if there was a lot of water it would show up in a more drastic way, but if there's water I don't want to trap it and allow it to rot.

 

[Burnerman]

No I don't think there will be any issues there.....any water spilt or otherwise quickly dissipates and you report the insulation is dry.
I must say I'm a bit flummoxed when you say the stain is slowly spreading, I have to admit!
Gutter problems manifest themselves nearer the wall really - or is there a lead valley above?
Can you see the slates / tiles easy enough from outside, just to consider their condition?
John

 

[dancubas]

No I don't think there will be any issues there.....any water spilt or otherwise quickly dissipates and you report the insulation is dry.
I must say I'm a bit flummoxed when you say the stain is slowly spreading, I have to admit!
Gutter problems manifest themselves nearer the wall really - or is there a lead valley above?
Can you see the slates / tiles easy enough from outside, just to consider their condition?
John

No lead valley, just the roof tiles. The tiles are not brand new, but they seem ok. The stain isn't too far from the wall actually, only about 3 inches or so. Here are a couple of pics from the roofer from back in february to show the work he did - he said water was coming in between the gutter and the fascia (I think that's the wooden board that looks knackered in the first pic). The second pic shows the work he did. It's possible water was leaking into the house for quite a long time before I bought it, that whole area does not look too healthy.

 

[Burnerman]

For sure, the roofer was right about the facia - water running around the back of the gutter causes that and the tiles look just fine to me.
I would have thought that the new undercloaking - if that is the correct term - would have been tucked under the old felt but maybe that wasn't possible......others may give their opinion.
Anyway, there's many roofs around with no felt at all, and as there's no water ingress I wouldn't be worrying!
Regards
John

 

[dancubas]

For sure, the roofer was right about the facia - water running around the back of the gutter causes that and the tiles look just fine to me.
I would have thought that the new undercloaking - if that is the correct term - would have been tucked under the old felt but maybe that wasn't possible......others may give their opinion.
Anyway, there's many roofs around with no felt at all, and as there's no water ingress I wouldn't be worrying!
Regards
John

Having done a little more research on this, do you think it could be possible that this is a sign of hygroscopic salts in the plaster? Just a (possibly slightly paranoid) thought.

 

[vinn]

The february photo shows a severely rotted wood fascia board - presumably the fascia was entirely replaced: but what with?
Strands of something can be seen on the fascia?
The ends (tails) of the rafters and the wall plate could have also been rotted at that time (Feb) - were any repairs made to them?
The first batten shown in that photo was irrelevant, & actually causing water pooling possibilities.

The tile headlap should be a min. of 75mm - your tile headlap is 50mm.

The Felt Supporting Tray in the second photo should run beneath the felt that its supporting not over it - this now means that any moisture running down the felt will creep under the tray, and possibly, eventually, into your ceiling.
Judging by the photo there is an ample overlap of felt under the tray.

FWIW:
The tile overhang into the gutter projects too far over the gutter - it will make cleaning the gutter difficult.
A few brickwork courses immediately below the fascia/eaves are black with years of water run-off.

 

[scruffybiker]

Having done a little more research on this, do you think it could be possible that this is a sign of hygroscopic salts in the plaster? Just a (possibly slightly paranoid) thought.

Very possible. Get a humidifier and run it in the room and see if the patch grows. Or darkens

 

[dancubas]

The february photo shows a severely rotted wood fascia board - presumably the fascia was entirely replaced: but what with?
Strands of something can be seen on the fascia?
The ends (tails) of the rafters and the wall plate could have also been rotted at that time (Feb) - were any repairs made to them?
The first batten shown in that photo was irrelevant, & actually causing water pooling possibilities.

The tile headlap should be a min. of 75mm - your tile headlap is 50mm.

The Felt Supporting Tray in the second photo should run beneath the felt that its supporting not below it - this now means that any moisture running down the felt will creep under the tray, and possibly, eventually, into your ceiling.
Judging by the photo there is an ample overlap of felt under the tray.

FWIW:
The tile overhang into the gutter projects too far over the gutter - it will make cleaning the gutter difficult.
A few brickwork courses immediately below the fascia/eaves are black with years of water run-off.

Thanks for this reply. Just to clarify the photos are before and after shots of the same area.
The fascia was not replaced, I'm pretty sure the roofer just put that thing on top. No other repairs were made.

The tile headlap of 50mm - is there a fix for this without re-tiling the whole roof?

Re. the Felt supporting tray - I don't know why he put this over the felt - should I get him to come back and fix this? There is no sign of water anywhere in the loft but from the comments here it seems he did not do this work properly. Could there be water coming in even if there is no sign of it directly above?

Re. the black brickwork - yes, the previous owners dealt with this, I think they bought the house in a poor state and did most of the work on it. Those black areas are not showing any signs of problems now, but there was definitely a problem here with that in the past.

Very possible. Get a humidifier and run it in the room and see if the patch grows. Or darkens

Thanks - I'm not going to be able to do this without major disruption. Is there another way of testing for salts? (I did the' taste test' and can taste nothing bitter or weird, but I know that's not really a conclusive test). And also, any recommendations for who I get to actually fix this, and what the procedure is?

 

[scruffybiker]

If it turns out to me salt. You can get stabalizer or hack the infected piece out and replace. That's what I done

 

[dancubas]

If it turns out to me salt. You can get stabalizer or hack the infected piece out and replace. That's what I done

Thanks for the quick reply - do you mean hack out the infected plaster and just re-plaster that area?

 

[scruffybiker]

Yes exactly that. Keep us updated