Damp issue with roof?

[yurio]

I live in an old Victorian house. The loft in the kitchen has been removed to make the room taller. Old chimney breast has also been removed with only a bit of it remaining to support the chimney stack outside that remained intact.

I've been having a number of leaks over the past couple of years and we really struggled to identify where it's coming from. In the process of figuring out what could be causing the leak we replaced the roof, re-rendered chimney crown and capped the flues with c-caps. It turns out in the end the main cause was the chimney stack. For some time I didn't see any new stains and it seemed like everything is fine.

During recent cold streak on the days when the temperature was negative I saw new stains appear in the middle of the ceiling.

Could this be caused by residual water that is still in the ceiling or does it have to do with insulation?

P.S. The last big leak happened in February last year, the smaller one could have happened at the end of summer. I'm not sure it fully dried out yet (at least moisture meter shows that the area next to the chimney stack is wet). Not sure if I should trust the moisture meter?

 

[Nige F]

Maybe air getting through those downlighters ? Have you got a hob extractor ?

 

[yurio]

What could be wrong about downlighters? Could you please explain?

I do have a hob extractor, but it’s broken (I open the window when cooking). Around the time when the leak happened no-one was cooking tho — I just got back from a trip at the time.

 

[Alastairreid]

Downlighters require holes to be cut in the plasterboard allowing moisture laden air to pass through and condense in the roof void.

 

[yurio]

Thank you. If that’s the case, what is the best solution here?

I assume whoever did in the first place haven’t thought about potential issues.

 

[foxhole]

You have a sealed chimney stack which will allow moisture thru and zero ventilation to combat it.

 

[Alastairreid]

Ventilate and insulate the roof void and manage the extraction of moisture with mechanical ventilation.

 

[yurio]

You have a sealed chimney stack which will allow moisture thru and zero ventilation to combat it.

C-cap at the top of the chimney stack allows ventilation tho, no?

Ventilate and insulate the roof void and manage the extraction of moisture with mechanical ventilation.

But there’s no roof void in my case, is there?

 

[Alastairreid]

Ceiling void!

 

[foxhole]

C-cap at the top of the chimney stack allows ventilation tho, no?

No .

 

[yurio]

C-cap at the top of the chimney stack allows ventilation tho, no?

No .

Why not? Or are you saying there should be a vent at the bottom of the chimney stack too?

 

[foxhole]

Why not? Or are you saying there should be a vent at the bottom of the chimney stack too?

No air movement without top and bottom vents .

 

[catlad]

I assume whoever did in the first place haven’t thought about potential issues.

Correct.

 

[catlad]

C-cap at the top of the chimney stack allows ventilation tho, no?

Those metal caps will not help your cause, I suggest getting some clay venting pots.

 

[yurio]

Those metal caps will not help your cause, I suggest getting some clay venting pots.

They are not metal, they are plastic. And they are letting air through without letting rain in (previously had issue with clay pots).