Damp 'spots' on upstairs chimney breast - Please help!

[richardbell81]

Hello,

If anyone can help I would be really grateful!

We bought our first house last year and after living in it for a few months (since September) I have noticed some strange damp spots on and around the chimney breast in the top bedroom. The house is 1902 terrace and the bedroom with damp patched is on the top/3rd floor. There are various patches which I think are down to various reasons. We had the roof patched up with broken slates replaced and the chimney stack re-pointed so i'm as confident as I can be that the roof is sound. I have uploaded a few pictures so you can see where the damp patches are forming and what they look like close up. As you can see they are fairly spread out. I am not so concerned about the ones next the ceiling as I think these are down to a bit of re-pointing that needs doing on the outside wall above the neighbours roof.

The patches which i'm not sure about are the ones on the chimney breast. As you can see from the pictures, some look quite different to others, and have only become a problem since around christmas time just after I re-painted the walls.

Neither of the chimneys are currently used . The one at the front of the house (on the right) has had the fireplace removed and blocked off. The one at the back of the house has been temporarily blocked up as we had an old gas fire removed but couldn't afford to put another one in.

Do you think the damp patches are down to poor ventilation, and if I put some air vents in is this likely to solve the problem, or do you think there could be any other reasons?

Thanks in advance, Rich.

Front (Right) stack - 1

• richardbell81
• 18 Feb 2013
• 1

Paint and plaster bubbling up

Rear (Left) stack - 3

• richardbell81
• 18 Feb 2013
• 1

damp / greasy patches

Rear (Left) stack - 2

• richardbell81
• 18 Feb 2013
• 1

damp 'spots' detail. Has weird white bits in centre of patches.

Rear (Left) stack - 1

• richardbell81
• 18 Feb 2013
• 1

damp 'spots'

 

[richardbell81]

I nearly forgot... all the areas were treated with damp proof paint before I re-painted! But that obviously didn't make much difference.

 

[tony1851]

It's possible the patches are caused by hygroscopic salts deposited in the brickwork. These are the byproducts of combustion. They frequently cause water vapour in the atmosphere to condense and can be confused with penetrating dampness

 

[richardbell81]

It's possible the patches are caused by hygroscopic salts deposited in the brickwork. These are the byproducts of combustion. They frequently cause water vapour in the atmosphere to condense and can be confused with penetrating dampness

Thanks for the reply. It could be possible, I'm just not sure why it didn't show up before... Maybe the light grey paint highlights the problem more???

Is there any way to get rid of it or at least cover it up?

 

[dann09]

1. Tony has put his finger on it - corrosive chemical action.
And, as you say, perhaps the exposed brickwork and flashing require attention.

2. You should research a large number of recent posts on here, ref this kind of thing.

3. Dont go cutting in new c/breast vents in the loft, you could create a potentially dangerous situation for some future occupier.

4. Suggest that you post pics of the exterior brickwork and flashing - and the two c/stacks.

5. Suggest that you also post pics of each room that has a c/breast - the fire opening or vent.

 

[richardbell81]

Hi Dann,

Thanks for the response. I've done as you suggested and updated the album with pictures of each exterior stack, and every room that has a chimney breast in it.

I've labelled each picture so you know whats what. A couple of points to note:

1. half of the rear chimney breast has been removed in the bathroom as the room is very small. It was done before we moved in and has a gas flu liner in it.
2. There is a free standing electric fire currently in the fireplace as we couldn't afford to install a real one so the chimney has been blocked up to stop dirt falling down it. I made a dummy flu out of a soil pipe (un-used!) which literally stands on the fire to make it look more realistic!
3. The front stack only goes as far down as the 1st floor as the front room downstairs used to be a shop. This is why there is no image of the downstairs front chimney breast.

If there is anything else you can think of then do let me know. I have looked around lots of forums but can't seem to find anything that matches my problem exactly. I have also had a few people come and look at it without being able to give me a definitive answer which is why i'm turing to this forum!

Hopefully someone can shed any more light on the matter.

Cheers

Top bedroom - damp spots

• richardbell81
• 19 Feb 2013
• 1

Front stack - outside

• richardbell81
• 19 Feb 2013
• 2

My house is on the left. Roof, flashing, ridge tiles recently done.

Front stack - outside

• richardbell81
• 19 Feb 2013
• 1

Front stack / bedroom

• richardbell81
• 19 Feb 2013
• 1

This bedroom is on the second floor below the top bedroom with the damp spots. I presume it once...

Rear Stack

• richardbell81
• 19 Feb 2013
• 2

My house on the left. Flashing recently been done.

Rear Stack - close up 1

• richardbell81
• 19 Feb 2013
• 1

Rear Stack - close up 2

• richardbell81
• 19 Feb 2013
• 1

Rear stack / bathroom

• richardbell81
• 19 Feb 2013
• 1

Half the stack has been removed (before we moved in) to allow room for a bath.

Rear stack - dining room

• richardbell81
• 19 Feb 2013
• 1

This is the base of the rear stack in doors. The fire is an electric one with a dummy flu pipe...

Rear stack - dining room

• richardbell81
• 19 Feb 2013
• 1

Close up of how we blocked it up. As you can see, the 'dummy flu' doesn't go anywhere.

 

[joe-90]

It's condensation. Nothing to do with your chimney.

 

[richardbell81]

It's condensation. Nothing to do with your chimney.

How can you be so sure? I'm not saying it isn't. Wouldn't condensation appear all over the walls and not just in those small patches?

There's absolutely no damp patches on any other wall except that one and the 2 chimney breasts?

 

[joe-90]

What happens is the mortar falls out between the bricks inside the chimney so the water doesn't have far to travel to reach the bedroom. Combine that with the chemicals that are contained in the wood burner smoke and when the steamy smoke goes up the chimney it condenses on the walls of the chimney and then through the gappy mortar.

It's dead common.

 

[richardbell81]

What happens is the mortar falls out between the bricks inside the chimney so the water doesn't have far to travel to reach the bedroom. Combine that with the chemicals that are contained in the wood burner smoke and when the steamy smoke goes up the chimney it condenses on the walls of the chimney and then through the gappy mortar.

It's dead common.

That would make sense... except that isn't a log burner. It's a free standing electric fire with a soil pipe stuck on top!

Both chimneys are blocked off.

 

[joe-90]

It is still dead common for warm moist air from the house to enter the chimney and condense. Once upon a time it DID have tar and chemicals that saturated the inner chimney and the moisture is using that as a vehicle. That is why it happens upstairs because that is where the chimney gets cooler.

 

[richardbell81]

It is still dead common for warm moist air from the house to enter the chimney and condense. Once upon a time it DID have tar and chemicals that saturated the inner chimney and the moisture is using that as a vehicle. That is why it happens upstairs because that is where the chimney gets cooler.

Is there any solution to this you know of?

 

[joe-90]

If you can stop the warm moist air getting up the chimney then it can't condense up there and will thus dry out.

Other than that the only way is to 'tank' the chimney breast so that moisture cannot penetrate and manifest itself in the room.

 

[dann09]

Thanks for the pics,

1. I'd suggest that you have sulpherisation in the chimney breast flues - ie. chemical reactions of old soot and fresh moisture "eating" it's way thro the brickwork and plaster to the surface where it attracts moisture from the air. This is not condensation.

2. I'd also suggest, that you have minor leaks at the back gutters and slightly up the slating - slipping, replacement and split slates. This leaking is showing near to the purlins. Can you get a view in the "loft" space, look for leaks, stains and underslate felt.
Is the lower roof your neighbour's? There's some step flashings missing.

3. The flaunching appears to be loose and it's probably allowing moisture into the flues to feed the sulpherisation. Plus the pointing is failing.

4. Do you know how the chopped off c/breasts are supported?

5. Is the black stove pipe in pics 8 and 9 false?

6. Pic 4 requires a vent in the c/breast.

7. If "dirt" was falling down the flue it would indicate something wrong in the flue or at the stack/terminal.

8. Have the flues ever been swept or camera examined?
There should be 4 terminals in total on each stack?

9. Suggest that the roof at the stacks and flaunching and flashings be inspected from a roof ladder.
Perhaps you will have to open up the fireplace (s) and sweep the flues with "chains".

10. Knock off all plaster to the bedroom c/breasts and render in a lime and sand mix, with a board or remedial finish. No tanking req'd.

11. Perhaps discuss these issues with your neighbour?

12. i give this advice with the proviso that i'm not there - my information is limited, someone on site might say different.

 

[dann09]

13. Redundant flues require venting - top and bottom.

14. All your flues are redundant then?