We have a chimney stack that is shared with our neighbour, four chimneys belonging to each house.
Our four are all open and in use.
The central wall in the chimney, above roof height (so the party wall between us and the neighbour) had lost a lot of mortar, and the spines between each separate chimney on our side had also degenerated, with the top two to four courses of the spine walls between each chimney on our side falling away.
The perimeter wall going right round the outside of the chimney stack was therefore lacking support.
This week a construction company were instructed to take down the whole stack to 2 courses above roof flashing and rebuild it again the same.
They informed us they would need to put a lead DPC/ cavity tray in it, which we agreed to. They put the tray in a course above where they had taken the chimney down to. It was effectively put on top of the existing central wall and spine walls (between each chimney). See photo.
I then assumed they would build upwards from the tray, on the perimeter walls, central wall and spine walls. They instead put a lintel onto the spine wall the build on top of (I do not understand why, as they could have bricked onto the lead DPC directly, unless perhaps a course had been lost under the tray on the spine but then don't see why they didn't rebuild it before applying the tray). The lintel wasn't fixed into the perimeter wall, unless they bracketed it to it.
Looking at the photo it looks like they placed the DPC with 2 bricks (one row) at one end missing and then realised they would be building at one end onto an unsupported DPC. I have no idea why they didn't replace the missing bricks on the central wall before placing the DPC, or if they didn't want to remove the DPC, cut and pull up a section, brick under it, and then put it back down.
It has now transpired that they then built up the central and perimeter walls of the stack but didn't rebuild the spine walls between the individual chimney.
As they have cobbled outwards (as a single skin with the cobble sat half a brick out) to match the previous design, they have realised that they are going to struggle to get the pots to sit on, so are placing roof slates across the chimney, cutting a hole in them for each individual chimney and then launching onto them.
I think it's nothing to do with the cobbling going outwards (as it returns to same width as lower part of chimney) that they can't place the pots, I think it's because they didn't rebuild the spine walls so have nothing for them to stand on.
They are now suggesting putting small lintels perpendicular to the central wall, effectively where the spine walls would have been had they rebuilt them between each individual chimney, however I don't see how they will now be attached to the chimney as they can only sit inside the perimeter of the chimney balanced across the central wall.
My concerns are:
We rebuilt the chimney as the spine walls had failed, leaving a weak perimeter wall to the stack. We now have a stack with a perimeter wall (albeit with new mortaring) but without spine walls (so effectively single skin with only the one central wall support), so have we achieved anything to structurally improve what we had?
We now have four individual chimney flues which terminate in a shared space in the chimney stack, which will then have 4 individual pots, will the shared space affect draught?
I'm also concerned that sweeping the chimney will be difficult with however they decide to mount the pots?
If they do mount the pots onto roof slates with holes cut in them, I am concerned as the chimney exit space (no longer 4 individual flues) is squared off corners, cutting the slate with a hole will leave corners that rising debris will get caught under preventing it vacating through the pots and be a fire risk, albeit the pots would have always been circular too.
Can anyone see the issues, or anymore, that I am seeing with the spine walls having not been rebuilt? I still don't see why they didn't, we now seem to be relying on a network of lintels which are not tied into the perimeter wall.
If they are proposing tying the final lintels which would replace the spine wall and seem to be an after thought into the perimeter wall of the stack then concrete lintels would show in the final course of the chimney, which I do not want. Am I then being reasonable to argue that we asked for it to be taken down and rebuilt as was and they should build the spine walls (even if it means taking down some of what they have built)?
I can't bear letting people work on my house for this very reason, but the other half wouldn't let me work on the roof (or the chimney which didn't leak after 100 years of being there) would have been rebuilt exactly as it was.
Appreciate peoples thoughts. It's upwards from the photo that the spines were not rebuilt with then 10 courses of perimeter and central wall rebuilt without the spine walls between each individual chimney.
Our four are all open and in use.
The central wall in the chimney, above roof height (so the party wall between us and the neighbour) had lost a lot of mortar, and the spines between each separate chimney on our side had also degenerated, with the top two to four courses of the spine walls between each chimney on our side falling away.
The perimeter wall going right round the outside of the chimney stack was therefore lacking support.
This week a construction company were instructed to take down the whole stack to 2 courses above roof flashing and rebuild it again the same.
They informed us they would need to put a lead DPC/ cavity tray in it, which we agreed to. They put the tray in a course above where they had taken the chimney down to. It was effectively put on top of the existing central wall and spine walls (between each chimney). See photo.
I then assumed they would build upwards from the tray, on the perimeter walls, central wall and spine walls. They instead put a lintel onto the spine wall the build on top of (I do not understand why, as they could have bricked onto the lead DPC directly, unless perhaps a course had been lost under the tray on the spine but then don't see why they didn't rebuild it before applying the tray). The lintel wasn't fixed into the perimeter wall, unless they bracketed it to it.
Looking at the photo it looks like they placed the DPC with 2 bricks (one row) at one end missing and then realised they would be building at one end onto an unsupported DPC. I have no idea why they didn't replace the missing bricks on the central wall before placing the DPC, or if they didn't want to remove the DPC, cut and pull up a section, brick under it, and then put it back down.
It has now transpired that they then built up the central and perimeter walls of the stack but didn't rebuild the spine walls between the individual chimney.
As they have cobbled outwards (as a single skin with the cobble sat half a brick out) to match the previous design, they have realised that they are going to struggle to get the pots to sit on, so are placing roof slates across the chimney, cutting a hole in them for each individual chimney and then launching onto them.
I think it's nothing to do with the cobbling going outwards (as it returns to same width as lower part of chimney) that they can't place the pots, I think it's because they didn't rebuild the spine walls so have nothing for them to stand on.
They are now suggesting putting small lintels perpendicular to the central wall, effectively where the spine walls would have been had they rebuilt them between each individual chimney, however I don't see how they will now be attached to the chimney as they can only sit inside the perimeter of the chimney balanced across the central wall.
My concerns are:
We rebuilt the chimney as the spine walls had failed, leaving a weak perimeter wall to the stack. We now have a stack with a perimeter wall (albeit with new mortaring) but without spine walls (so effectively single skin with only the one central wall support), so have we achieved anything to structurally improve what we had?
We now have four individual chimney flues which terminate in a shared space in the chimney stack, which will then have 4 individual pots, will the shared space affect draught?
I'm also concerned that sweeping the chimney will be difficult with however they decide to mount the pots?
If they do mount the pots onto roof slates with holes cut in them, I am concerned as the chimney exit space (no longer 4 individual flues) is squared off corners, cutting the slate with a hole will leave corners that rising debris will get caught under preventing it vacating through the pots and be a fire risk, albeit the pots would have always been circular too.
Can anyone see the issues, or anymore, that I am seeing with the spine walls having not been rebuilt? I still don't see why they didn't, we now seem to be relying on a network of lintels which are not tied into the perimeter wall.
If they are proposing tying the final lintels which would replace the spine wall and seem to be an after thought into the perimeter wall of the stack then concrete lintels would show in the final course of the chimney, which I do not want. Am I then being reasonable to argue that we asked for it to be taken down and rebuilt as was and they should build the spine walls (even if it means taking down some of what they have built)?
I can't bear letting people work on my house for this very reason, but the other half wouldn't let me work on the roof (or the chimney which didn't leak after 100 years of being there) would have been rebuilt exactly as it was.
Appreciate peoples thoughts. It's upwards from the photo that the spines were not rebuilt with then 10 courses of perimeter and central wall rebuilt without the spine walls between each individual chimney.
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