Wood burner flue - leak and damp ceiling

[Beverly27]

Earlier this year, we noticed water running down the outside of our twin-walled wood-burning flue when it rained, gathering on the top of the stove. We fitted a storm collar, which briefly seemed to solve the problem. However, the water soon returned with the rain. I have since removed the ceiling finishing plate, and as the photos from when it was raining show, the internal surfaces of the flashing and flashing rubber are both wet, as is the rafter bracket and membrane. There also appears to be mould on the lowest rafter, which can be seen in the photos. We also have visible damp patches on the ceiling close to where the flue is installed, albeit above and below (and behind) it. The guy who installed it has disappeared, and the couple of roofers who have looked at this have either been unable to help or reluctant to assist due to the flue. There is also what appears to be efflorescence on the external wall beneath the coping stones. Therefore, I’m reaching out for advice on properly addressing this problem(s) because we’re now stuck with a leak that we don’t know how to fix. My questions are:
1. What could be the cause of the problem, and how do we address it?
2. Is the dampness in the ceiling above the flue likely related (there is only damp in the area of the flue)?
3. Can we treat the mould, or are more drastic measures required? If so, what?
4. Do we need to check the length of this rafter to see if there is more damp?
5. What is the cause of the efflorescence?

Thank you.

Thanks all.

 

[Burnerman]

Storm collars are all well and good, but I think you need to free it, move it up out of the way and inspect the rubber flashing for perishing, split or whatever......including the area secured by that large jubilee clip.
At the same time, get rid of the moss nearby - which could include around the Velox.
John

 

[noseall]

Earlier this year, we noticed water running down the outside of our twin-walled wood-burning flue when it rained, gathering on the top of the stove. We fitted a storm collar, which briefly seemed to solve the problem. However, the water soon returned with the rain. I have since removed the ceiling finishing plate, and as the photos from when it was raining show, the internal surfaces of the flashing and flashing rubber are both wet, as is the rafter bracket and membrane. There also appears to be mould on the lowest rafter, which can be seen in the photos. We also have visible damp patches on the ceiling close to where the flue is installed, albeit above and below (and behind) it. The guy who installed it has disappeared, and the couple of roofers who have looked at this have either been unable to help or reluctant to assist due to the flue. Therefore, I’m reaching out for advice on properly addressing this problem because we’re now stuck with a leak that we don’t know how to fix. My questions are:
1. What could be the cause of the problem, and how do we address it?
2. Is the dampness in the ceiling above the flue likely related (there is only damp in the area of the flue)?
3. Can we treat the mould, or are more drastic measures required? If so, what?
4. Do we need to check the length of this rafter to see if there is more damp?

Thank you.
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Thanks all.

Is there any insulation in that roof or vapour check detailing? It all looks a bit lean (on the thin side) to me.

 

[Burnerman]

Can I see condensation on the underside of the rubber.....or is it me cataracts?
John

 

[foxhole]

How does the roof drain adjacent the parapet wall? May be flooding if gutters are blocked.

 

[Beverly27]

Storm collars are all well and good, but I think you need to free it, move it up out of the way and inspect the rubber flashing for perishing, split or whatever......including the area secured by that large jubilee clip.
At the same time, get rid of the moss nearby - which could include around the Velox.
John

Thanks, John. I'll make sure to do what you suggested.

 

[Beverly27]

Is there any insulation in that roof or vapour check detailing? It all looks a bit lean (on the thin side) to me.

Thanks. There is insulation (2nd photo) and what looks like vapour check detailing (photo 1 - Cromar Vent3). The insulation just isn't in the small section of the roof surrounding the flue.

 

[Beverly27]

Can I see condensation on the underside of the rubber.....or is it me cataracts?
John

Definitely not cataracts, John! It's the water I described on the flashing rubber. I'm not sure if it's condensation or rainwater that has ingressed.

 

[Beverly27]

How does the roof drain adjacent the parapet wall? May be flooding if gutters are blocked.

The roof drain seems to work well. The gutters are pretty clear.

 

[noseall]

I'm not sure if it's condensation or rainwater that has ingressed.

The whole insulation/vapour control thing looks poor. There is no foil tape visible and no layer of insulation running across the the rafters either.

crank3.jpg

• noseall
• 22 Dec 2022

Vaulty2

• noseall
• 15 May 2022

Foil1

• noseall
• 2 Apr 2019

Foil3

• noseall
• 2 Apr 2019

 

[Beverly27]

The whole insulation/vapour control thing looks poor. There is no foil tape visible and no layer of insulation running across the the rafters either.

crank3.jpg

• noseall
• 22 Dec 2022

Vaulty2

• noseall
• 15 May 2022

Foil1

• noseall
• 2 Apr 2019

Foil3

• noseall
• 2 Apr 2019

Thank you. I suspect there's little we can do about this without incurring significant expense, right? What I must do is address the leak, though.

 

[ree]

OP,
Besides the various possibilities commented on above, & given the fibre cement slates, I wonder if the verge is watertight - why not post a pic of the verge?

 

[Beverly27]

OP,
Besides the various possibilities commented on above, & given the fibre cement slates, I wonder if the verge is watertight - why not post a pic of the verge?

Thanks. I'll take some photos tomorrow.

 

[Beverly27]

OP,
Besides the various possibilities commented on above, & given the fibre cement slates, I wonder if the verge is watertight - why not post a pic of the verge?

Here are some photos of the verge. Thanks again.

 

[ree]

OP,
The verge(s) are not the problem.
A pic of the roof abutment with the wall might show something - its only a possibility but worth a look at how the abutment has been flashed?


FWIW:
the staining on the render below the parapet capping is possibly due to:
1. the coping stones are not wide enough to throw off water and
2. the drip channel under each coping need raking with a flat screwdriver - raking will clear any blockages in the channel.
3. maybe the mortar perps & beds are failing.

The fragile membrane gutter is actually a back gutter & should have been built & lead flashed as such.