Damp Chimney / incorrect flashing?

[Andrewd8323]

Hi all

I started another thread which was about damp joists in our loft (here) and in one of the subsequent responses I mentioned how things have progressed and a damp chimney breast is now our key issue. I'm therefore creating a new thread to focus explicitly on the chimney. Apologies if you've read my problem twice as a result but I need to get to the bottom of the chimney issue as a priority and I was worried it wouldn't get seen in the other thread given it is just mentioned in a response.

I've just had my house re-roofed (new membrane, new battens , new thin edge sandtoft concrete tiles, and new dry ridge system).

Since then, we've had plenty of rain and we've had damp marks develop on the chimney breast in our bedroom - I've attached a photo of this (1490)

I've also been in the loft during heavy rain and the chimney breast has been wet to touch - video here

I have been struggling to engage with the roofer who did the original work, so I got an alternative roofer round. He said that the flashing has been done incorrectly on the chimneys for the roof tile that's been used.

I then took a photo of the flashing and sent it to the tile manufacturer, who agreed it hadn't been done right and said soakers needed adding due to the flatness of the roof tiles that have been used - I've attached photos of the flashing (see 1348 and 1349 below)

The roofer who did the original work came round yesterday, peeled back the flashing and essentially said "there is no evidence of water getting beneath the flashing, the roof is all fine. Moist air must be entering the loft from the house then condensing on the chimney and running down into the bedroom beneath. You need to insulate the floor of the loft better and less moist air will get up there".

I'm feeling at a bit of a loss now. I'm struggling to believe that it is condensation given we've been told by two other parties that the flashing has been done incorrectly. The size of the staining and amount of water also seems high for condensation. We also have a dry hip / ridge system, breathable membrane and vented eaves trays, so I would have thought there is enough ventilation up there to prevent significant amounts of condensation. In addition, I've only seen the chimney in the loft get wet during periods of heavy rain. I went up there yesterday morning (which was a very cold morning with no rain) and the chimney was dry to touch. If this was a condensation problem I would have expected it to be wet on a day like that as the bricks were very cold. So I'm really struggling to believe him.

So this is just a broad plea for any advice really - any suggested next steps?! What would you do? Do you think it could be condensation?

The only possible next steps I can think of are:
1) Ask the roofer to fit some vented roof tiles to increase airflow - if the problem still happens after this then surely it can't be condensation.
2) Insist the original roofer does the flashing as per the manufacturer's instructions

Thanks all

Andrew

 

[datarebal]

Maybe lack of chimney tray ..a common problem with only one reliable fix

 

[Andrewd8323]

Hi all

The damp marks on the chimney are getting worse by the day. Attached below is:
* A picture of the damp marks this morning
* Two pictures of the back gutter

I've also taken a video of the back gutter that capture more aspect of the back gutter here. Apologies it's a bit wobbly - I was up a ladder with my phone sellotaped to the end of a pole!

While I was up there I noticed that the pointing on the stack was darker in places and there were streaks on the chimney (as part of the re-roof the roofer re laid the top few courses of the chimney and repointed the entire thing). I'm not sure if this could be related to the issues? I've therefore also taken a video showing the full chimney stack here.

Thanks

 

[johnny2007]

My 2 pennies.
Your problem is where I marked in red.

 

[^woody^]

If there was no damp before the work, then the work is likely the problem, not condensation.

Which side of the beast is damp relative to the stack above?

Did you have work done to the top of the chimney?

 

[Andrewd8323]

My 2 pennies.
Your problem is where I marked in red.

Thanks @johnny2007 - can you see something in particular that makes you think that?

 

[Andrewd8323]

If there was no damp before the work, then the work is likely the problem, not condensation.

Which side of the beast is damp relative to the stack above?

Did you have work done to the top of the chimney?

Hi Woody

The side of the chimney breast that is showing the damp marks is the side that Johnny has marked up in red.

As part of the reroofing the roofer rebuilt the top few courses of the chimney to include a drip course and repointed the entire chimney

Thanks!

 

[johnny2007]

Thanks @johnny2007 - can you see something in particular that makes you think that?

Yes, there's a nice valley there where water can get under the lead.
They should've used tiles on top of the lead there so water would've run to the side of the back gutter.
Unless I am seeing it wrong from the pictures, it looks like they just used some mortar there.

 

[Andrewd8323]

Thanks all for input so far.

One additional question: the roofer repointed the chimneys at the time of doing the roof. I’ve attached a picture of them below. What are people’s views on the pointing? Look ok? I ask because the different shades look a bit unusual to my untrained eye. Could this be a source of the problem? I don’t think the chimney was painted with storm dry when it was worked on. If I did this would it protect both the bricks and pointing?

 

[Andrewd8323]

Thanks all for input so far.

One additional question: the roofer repointed the chimneys at the time of doing the roof. I’ve attached a picture of them below. What are people’s views on the pointing? Look ok? I ask because the different shades look a bit unusual to my untrained eye. Could this be a source of the problem? I don’t think the chimney was painted with storm dry when it was worked on. If I did this would it protect both the bricks and pointing?

Sorry to hassle - just wondering if anyone has any views on this?

 

[johnny2007]

Can't judge the pointing from that picture because it doesn't look like new pointing.
Did you see them doing it?
It's extremely unlikely that would be the source of damp.
Anyhow, I know it's unnecessary but I use brick seal on my chimney and redo it every 5 years.
That's because when I rebuilt it, the bricks didn't need any tool to be lifted.
They were just there held by their own weight.
They get a lot of battering from the weather up yhere.

 

[Andrewd8323]

Can't judge the pointing from that picture because it doesn't look like new pointing.
Did you see them doing it?
It's extremely unlikely that would be the source of damp.
Anyhow, I know it's unnecessary but I use brick seal on my chimney and redo it every 5 years.
That's because when I rebuilt it, the bricks didn't need any tool to be lifted.
They were just there held by their own weight.
They get a lot of battering from the weather up yhere.

I didn’t see them do it but I think they did - I definitely paid them to! Yes im thinking sealing it would be a good idea

 

[johnny2007]

If you get up there it will be obvious if they've redone the pointing or not.
But as said, I don't think that's the source of dampness.

 

[tomm12]

As noticed in the other thread someone mentioned the flashing is the problem and I agree.
You will have to get up there and lift the back gutter flashing and the tile course above the back gutter, and see if the roof felt is arranged properly then re-set the felt, the back gutter and the tiles.
With those tiles soakers are needed at the chimney stack sides not extended cover flashing.
Take a hose pipe on the roof and water test everything as you go.
The pointing is a bit of a red herring. Its bad but its not the problem.

 

[Andrewd8323]

As noticed in the other thread someone mentioned the flashing is the problem and I agree.
You will have to get up there and lift the back gutter flashing and the tile course above the back gutter, and see if the roof felt is arranged properly then re-set the felt, the back gutter and the tiles.
With those tiles soakers are needed at the chimney stack sides not extended cover flashing.
Take a hose pipe on the roof and water test everything as you go.
The pointing is a bit of a red herring. Its bad but its not the problem.

.