Damp on chimney breast

[aloha99]

Morning all

We have had a damp patch at the top of our chimney breast for quite some time but it has started getting worse.

The house is Victorian and two out of the three pots are capped. Since we bought the house we have had a wood burner installed and the chimney lined etc including a cowl. We have had UPVC facias and soffits installed with a few vents to the rear side of the house (less than original) but no other venting. The loft insulation appears to go all the way to the edge so no real air flow. The roof was replaced approx 15 years ago with concrete tiles and new felting.

The damp patch first started on the LHS of the chimney breast which is below the two capped pots but is now also on the RHS where the open pot is. There is also a small patch on the opposite side of the cimney breast.

We were originally told the damp patchs was due to a couple of holes in the lead, lead not overlapping a tile properly and also where the felt had degraded and this was repaired. After that we did have a lot of water come in on one occasion where it ballooned the paint off the wall and had to be pierced to let it out but this hasnt happened since. There are some old watermarks on the chimeny but I havent seen water running down the chimney.

The chimney has been painted with Stormdry and I was told that all the pointing etc was fine at that point. I was also told that there is some cracking in the flaunching but that shouldnt be causing any issues. When in the loft I can see small bits of daylight around the chimney but I presume this is where the step flashing meets the wall.

The damp patch doesnt seem to dry out in the summer after periods without rain. There is evidence of too much humidity in the loft as there is white mould on the beams and you can see where water has dripped onto surfaces.

In the loft the chimney breast reads 23 - 26% moisture where it meets the ceiling below but 8 - 11% above where it meets the roof felt. I realise that moisture testers arent great but....

I have no idea where the moisture is getting or where to start so any advice would be appreciated

Cheers

 

[ree]

OP,
The immediate concern would be the lead flashing - it has been installed incorrectly.
The flaunching has cracks, and does not project beyond the brickwork.
Thee brown marks suggest that the metal cowl is possibly rusting (or not attached to the SS flue liner)?
Is the wood burner operating correctly with the correct temp. fuel?
You have three flues and three fireplaces in that chimney breast.
Were any of the two redundant flues swept before blocking them off(?) - do these two flues have ventilation at the bottom/the fireplace?
Some of the loft chimney breast brickwork is damp.
The sand & cement fillet on the stack needs replacing.

You might consider replacing the flaunching & raking out to 25mm and re-pointing?

 

[aloha99]

OP,
The immediate concern would be the lead flashing - it has been installed incorrectly.
The flaunching has cracks, and does not project beyond the brickwork.
Thee brown marks suggest that the metal cowl is possibly rusting (or not attached to the SS flue liner)?
Is the wood burner operating correctly with the correct temp. fuel?
You have three flues and three fireplaces in that chimney breast.
Were any of the two redundant flues swept before blocking them off(?) - do these two flues have ventilation at the bottom/the fireplace?
Some of the loft chimney breast brickwork is damp.
The sand & cement fillet on the stack needs replacing.

You might consider replacing the flaunching & raking out to 25mm and re-pointing?

Hi Ree

Thanks for the reply, and to answer some questions

Is the wood burner operating correctly with the correct temp. fuel?
Yes but hasnt been used since April time.

You have three flues and three fireplaces in that chimney breast.
Only two fireplaces that I am aware of, one in use in the living room (multi fuel) and one in the bedroom above (room with the damp) which was blocked off some 30+ years ago. If there was ever a third I dont know where

Were any of the two redundant flues swept before blocking them off(?) - do these two flues have ventilation at the bottom/the fireplace?
No idea and no

Can you tell me what is wrong with the lead flashing please? This was installed when the roof was replaced and didnt pose a problem for all that time until after we bought the house and the various changes were made. The only issues that I was told about was a crack and a hole both of which were welded and also the bakc apron didnt go over a tile completely and the "patch" was put over the top just to be safe.

How would the flaunching project beyond the brickwork? I thought that was the job of the two courses of bricks that project out from the rest of the stack?

Is there any reason to rake out and repoint if the pointing is in good condition?

Many thanks

 

[ree]

OP,
You use profiled tiles with that kind of flashing.
Each of your tiles should have its own individual soaker - the step flashing would then be the cover flashing covering the soaker upstands.
Each stepped flashing should be turned into a 25mm chase - if you can see light from below there are gaps.
The unusual piece of lead at the RH of the back gutter could possibly be introducing water below the tiles?
Is this the "patch" you referred to?
You have a pot for each flue - all flues are separate, therefore you have three flues in that c/breast & stack &, if the have been retained, three fireplaces below.
google pics or diagrams for flaunching projection? Calder lead for flashing diagrams.

Pointing is simply a consideration - your original beds & perps have lime mortar but sand & cement has been used for any re-pointing: and its failing.

 

[mrrusty]

The immediate concern would be the lead flashing - it has been installed incorrectly.

+1

 

[aloha99]

OP,
You use profiled tiles with that kind of flashing.
Each of your tiles should have its own individual soaker - the step flashing would then be the cover flashing covering the soaker upstands.
Each stepped flashing should be turned into a 25mm chase - if you can see light from below there are gaps.
The unusual piece of lead at the RH of the back gutter could possibly be introducing water below the tiles?
Is this the "patch" you referred to?
You have a pot for each flue - all flues are separate, therefore you have three flues in that c/breast & stack &, if the have been retained, three fireplaces below.
google pics or diagrams for flaunching projection? Calder lead for flashing diagrams.

Pointing is simply a consideration - your original beds & perps have lime mortar but sand & cement has been used for any re-pointing: and its failing.

Thanks for the info,

I have no idea why there are three pots / flues as the stack serves the living room with the multi fuel burner and the bedroom above it which has been bricked up. The opposite side of the stack is the stairs so no place for a third fire so not sure what is going on there.

The photos show the issues that I was told were the cause of the damp patches which were "repaired" but I will now get quotes for what you have suggested and hopefully be someone who knows what they are doing.

Thanks for your help.