roof leak cause

[yawnbros]

I have a slowly worsening leak on the top room in my house. The house was built in 2003 with a study in roof space of the house. Several years ago a faint mark appeared on the inside slope of the roof(highlighted blue). A year or so later, marks appeared above the 2 windows and then more recently significant shadow marks appeared near the chimney (highlighted red). This has spread and damp readings show figures of between 15% and 23%.

I have called out some roofing guys and they have taken a look and applied some sealant in a few places but this has not helped at all. I have used a drone to take further pictures as attached but these don't really seem to show a clear cause. There does seem to be some faint cracks on the chimney and a few marks but I'm not convinced these would explain marks of this extent.

Any suggestions of what to do next or possible causes would be very gratefully appreciated.

 

[Alastairreid]

Is the flue getting used for gas?

 

[yawnbros]

Is the flue getting used for gas?

Yes, there’s a gas stove at the bottom of the chimney. We don’t use it very often at all though.

 

[Nige F]

Gas stove @ the bottom of the chimney and a gas vent used on a flexible flue liner on the top of the pot ?? And a green moss ? ring around it. I would say that's where the damp is getting in . You need a Registered Gas Safe engineer to ascertain what the gas terminal is doing. Seems odd to vent a cooker like that But safety First round gas !

 

[yawnbros]

I’ve probably not used the right term, it’s an old fashioned looking gas fire and we have not used it for probably a year as we have central heating.

Gas stove @ the bottom of the chimney and a gas vent used on a flexible flue liner on the top of the pot ?? And a green moss ? ring around it. I would say that's where the damp is getting in . You need a Registered Gas Safe engineer to ascertain what the gas terminal is doing. Seems odd to vent a cooker like that But safety First round gas !

 

[Nige F]

Fair enough but it still wants the GS engineer, maybe remove fire and liner then let the chimney breathe. I thought it was a stove in a fireplace alcove in a kitchen

 

[Alastairreid]

Same train of thought as nige, i would replace the gc1 terminal with a Gc2 clay terminal...but that would be down to the gas bod.

 

[bobasd]

the flue (how many fire places do you have below?)) must not have ever been swept?
there's amounts of flue soot condensate seeping through your chimney stack - on the outside as dark smudges, and internally as damp stains.
given the 2003 age, & the use of a gas fire, there must have been a heavy use of solid fuel (wet wood?) before the gas fire & liner were fitted.

compounding the soot problem there appears to be moisture leaking into the chimney breast & stack.
streaks can be seen from the terminal top to the smooth stone of the stack.
a 2003 build should have built-in stack DPC. i doubt yours has one?
the flashing appears to be fine except that the lead saddle should have extended further along the ridge tile.

the flaunching is fraying at the edges - and is there an adequate throating (about 50mm) in the flaunching projection?
the metal terminal installation is pooling water.

best practice would be to erect a tower, & remove the terminals and flaunching down to stonework - then remove the SS liner.
then sweep the flue(s?).
Re-build the flaunching (use SBR Latex in the mix) and terminal after determining the future of any fireplace appliance/liner.

Or you could simply remove the liner, sweep the flue, and soak the flaunching with a "water proofer" - & a correctly installed flue terminal?

all damp stains in the bedroom will have to be hacked off or cut out -
perhaps read, fwiw, my previous posts on dealing with c/breast damp etc?

 

[^woody^]

That chimney looks like it wont have a DPC, and it should have.

 

[datarebal]

That chimney looks like it wont have a DPC, and it should have.

It does not, it should have, and no reason not to.... plus capped ridge are damaged