mr-squirrel
Member
- Messages
- 27
- Location
- Perthshire, Scotland
Hi there,
I have some chimney problems and i'm looking for suggestions on the best way to resolve them.
On the party wall between me and the neighbours there is a disued twin-flue chimney. The two fireplaces it connects are both on the neighbours side - their house was built first, with my house built on afterwards to share their gable wall. The fireplaces are disused and hidden at the neighbours side, i don't know how they have been blocked off.
Wall construction is random rubble in the local pink sandstone bedded on soft lime mortar. The stone has a very high capillary rise and just loves to soak up water - and we have had plenty of that lately. Weeks of rain with no wind to help things dry out.
I woke up at 5am one morning to hear bits of rubble falling down the back of the wall. The following day i went up into the loft for a look around and found a small hole had appeared under the chimney stack in the gable wall.
You can clearly see a line of damp decending the wall that is getting in around the chimney stack (notice dark line at 45 degrees on rectangular block of stone):
Although not recent, you can see in the past water has stained the masonry at a lower level.
And then further up, this:
You can see a small hole has appeared. The stone is so soft it turns to dust when it hits anything - this is what made the noise.
As the weather did not lend to climbing on the roof, i thought i would get the moisture meter out:
Clearly we have some very damp air floating about in the chimneys! I'm sure if i left the meter for longer it would have gone way over 90%.
Managed to get a couple of shots through the hole, and we can see the problem!
This is obviously the stubs of clay liner that stop short where the flue transitions from the brick chimney stack, to the wall. The infil round the liner has obviously been falling out for years - fairly typical.
Water ingress on both the inside, and outside of the liner. And looks like it has been like that for some time. So it was definitley time to get up on the roof!
One pot was open, and the other capped with slate - a very long time ago. A neatly trimmed piece of slate was simply resting on top of the pot. I have no idea how the wind didn't blow it off - it had clearly been there for a very long time!
Looking down the flues:
We can see the liners have gone slightly green showing water has been getting in for a long time.
At the very least the two top courses of brick are knackered, there is more moss than mortar.
The pots were simply sitting there and lifted straight out! Whoever last fitted the pots was clearly an idiot - nothing of substance to anchor them down. And the liner in one flue is obviously short, so it was simply resting on the cut bricks! The slate and flaunching neatly serve to allow water in, but ensure it can't dry out readily.
The lower brickwork seems reasonably solid when tapped with a hammer, looks like a rake out and re-point is all that is needed though i may change my mind during the downtakings! Only a couple of bricks are frost damaged, which are be easily replaced.
Obviously the cement flashing is knackered and useless as a flashing anyway. This will all be replaced in lead in due course. Same with the cable entry. Surprisingly there is very little water ingress from the crappy flashings, most of it has been straight down the stack.
So, current thinking is to take down the stack as required until i get to sound material, and rebuild. I should be able to re-use the bricks as they appear sound. The mortar is fairly soft so will probably come off them cleanly. Luckily the pots are in perfect condition so can go back on later. I will obviously be fitting rain hats that allow for maximum ventillation. If the fireplaces were ventillated at the bottom, i'm sure they will have been blocked by all the years of falling debris. I doubt this will be a problem once i stop water getting in.
However, what to do about the rotten stone under the stack? It shows no signs of leaning but i've no doubt the stone is thin in places and pretty soft due to all the water and salts travelling through it over the years. I have plenty of spare stone so can easily cut some new pieces and replace it, however what worries me is i open the wall up and chase endlessley downwards searching for something solid to rebuild on.
I guess i'll have to pop a camera down into the hole and have a good look round in the void to get a measure on the condition of the stone. The diving wall between the two flues has eroded away quite a bit creating a void where the clay liners stop and dividing wall starts. I think dismantling and rebuilding the whole stack (to just below roof level), fixing the wall, then rebuilding the stack would be over the top, however it would be silly to do a good repair above the roofline and leave any issues in the wall un-resolved. I'll have to get scaffold up to work safely so want to make full use of whatever that is going to cost.
I have no intention of removing the stack as it is an important feature, adding much needed character. It is a conservation area too, a neighbour across the road tried to remove one of his and he was turned down by planning.
Any comments welcome!
Thanks,
I have some chimney problems and i'm looking for suggestions on the best way to resolve them.
On the party wall between me and the neighbours there is a disued twin-flue chimney. The two fireplaces it connects are both on the neighbours side - their house was built first, with my house built on afterwards to share their gable wall. The fireplaces are disused and hidden at the neighbours side, i don't know how they have been blocked off.
Wall construction is random rubble in the local pink sandstone bedded on soft lime mortar. The stone has a very high capillary rise and just loves to soak up water - and we have had plenty of that lately. Weeks of rain with no wind to help things dry out.
I woke up at 5am one morning to hear bits of rubble falling down the back of the wall. The following day i went up into the loft for a look around and found a small hole had appeared under the chimney stack in the gable wall.
You can clearly see a line of damp decending the wall that is getting in around the chimney stack (notice dark line at 45 degrees on rectangular block of stone):
Although not recent, you can see in the past water has stained the masonry at a lower level.
And then further up, this:
You can see a small hole has appeared. The stone is so soft it turns to dust when it hits anything - this is what made the noise.
As the weather did not lend to climbing on the roof, i thought i would get the moisture meter out:
Clearly we have some very damp air floating about in the chimneys! I'm sure if i left the meter for longer it would have gone way over 90%.
Managed to get a couple of shots through the hole, and we can see the problem!
This is obviously the stubs of clay liner that stop short where the flue transitions from the brick chimney stack, to the wall. The infil round the liner has obviously been falling out for years - fairly typical.
Water ingress on both the inside, and outside of the liner. And looks like it has been like that for some time. So it was definitley time to get up on the roof!
One pot was open, and the other capped with slate - a very long time ago. A neatly trimmed piece of slate was simply resting on top of the pot. I have no idea how the wind didn't blow it off - it had clearly been there for a very long time!
Looking down the flues:
We can see the liners have gone slightly green showing water has been getting in for a long time.
At the very least the two top courses of brick are knackered, there is more moss than mortar.
The pots were simply sitting there and lifted straight out! Whoever last fitted the pots was clearly an idiot - nothing of substance to anchor them down. And the liner in one flue is obviously short, so it was simply resting on the cut bricks! The slate and flaunching neatly serve to allow water in, but ensure it can't dry out readily.
The lower brickwork seems reasonably solid when tapped with a hammer, looks like a rake out and re-point is all that is needed though i may change my mind during the downtakings! Only a couple of bricks are frost damaged, which are be easily replaced.
Obviously the cement flashing is knackered and useless as a flashing anyway. This will all be replaced in lead in due course. Same with the cable entry. Surprisingly there is very little water ingress from the crappy flashings, most of it has been straight down the stack.
So, current thinking is to take down the stack as required until i get to sound material, and rebuild. I should be able to re-use the bricks as they appear sound. The mortar is fairly soft so will probably come off them cleanly. Luckily the pots are in perfect condition so can go back on later. I will obviously be fitting rain hats that allow for maximum ventillation. If the fireplaces were ventillated at the bottom, i'm sure they will have been blocked by all the years of falling debris. I doubt this will be a problem once i stop water getting in.
However, what to do about the rotten stone under the stack? It shows no signs of leaning but i've no doubt the stone is thin in places and pretty soft due to all the water and salts travelling through it over the years. I have plenty of spare stone so can easily cut some new pieces and replace it, however what worries me is i open the wall up and chase endlessley downwards searching for something solid to rebuild on.
I guess i'll have to pop a camera down into the hole and have a good look round in the void to get a measure on the condition of the stone. The diving wall between the two flues has eroded away quite a bit creating a void where the clay liners stop and dividing wall starts. I think dismantling and rebuilding the whole stack (to just below roof level), fixing the wall, then rebuilding the stack would be over the top, however it would be silly to do a good repair above the roofline and leave any issues in the wall un-resolved. I'll have to get scaffold up to work safely so want to make full use of whatever that is going to cost.
I have no intention of removing the stack as it is an important feature, adding much needed character. It is a conservation area too, a neighbour across the road tried to remove one of his and he was turned down by planning.
Any comments welcome!
Thanks,
