Diagonal chimney in the middle of loft...?

smpNWI

Currently in the process of buying a terraced 1930s-50s house.

We're hoping to eventually convert the loft but when we went into it during the second viewing, we found this chimney breast right in the middle of it, which is also rendered it seems (?). It's then going off diagonally towards the neighbours'. Looking from the outside, it seems like our house shares a chimney stack with those neighbours.

We've checked next door on Rightmove and the chimney breasts and fireplaces are also in the centre of the rooms (rather than on the party walls). Some others in the same row of terraces have them on party walls, but a few are in the centre like hours.

I've managed to find one picture online of a neighbour who have converted their loft, and it looks like they weren't able to get rid of their chimney breast (second pic below).

Now this is a big hit as this potential for loft conversion was key to choosing this property.

• Is there a chance we can remove this without neighbours' consent if we add support on our side? What type of support would we be talking about (gallows brackets?) and how costly should we expect the materials to be?
  
  
• I've seen mention of steel dormers as alternatives to other types of support. However, wouldn't the dormer have to extend exactly opposite the chimney to provide such support?
  
  
• If we magically got the neighbours to agree to removing on both sides (and the chimney stack), what sort of costs would you expect for removing the chimney stack and this chimney breast only on our end?
  
  
• Any other ideas on how we could work around this? Is the second image below our only option for a conversion now? Embrace the chimney/make it into shelves?
  
  
• Why would this be done in the first place? Is there any benefit to this diagonal configuration? Just curious!
  
  

Would anyone know...? Thank you!

stuart45

smpNWI said:

which is also rendered it seems (?). 

If it's in London, regs at that time required flues with less than 9 inches of brickwork in the loft to be rendered.
The answers to the other questions are a bit less straightforward.
A structural engineer is the best person to contact. Generally when removing a chimney breast in the loft you need at least 2/3 of the brickwork below the roof line.at the lowest point. There's also the issue of the thrust from the other chimney not being balanced up from your side.
Apart from doing something like the shelving photo I'd say your best chance would be for the neighbour to want the same.
It was probably built like that to balance up the external look of the terrace, with all having the same chimneys.
The cost would be thousands, rather than hundreds, but best to get a few local ideas.

Albermarle

What are the 'danger' signs about ?

FreeBear

Albermarle said:

What are the 'danger' signs about ?

Probably to warn about lack of boards under the loft insulation - Got a couple up in my loft.

noitsnotme

We had 2 shared stacks removed to just below the roof line and the roof made good back in 2020.  Total cost was £3200, split between us and next door.  The way costs have risen in the last 4 years I wouldn't be surprised if it cost twice that now!

smpNWI

Albermarle said:

What are the 'danger' signs about ?

As @FreeBear said, just to warn about lack of boards. Quite standard afaik

gzoom

smpNWI said:

• Why would this be done in the first place? Is there any benefit to this diagonal configuration? Just curious!
  

It would have been like that because of the fire place below and where the chimney needs to exit the roof line. In our case we had a sky light above the fire place so had to a diagonal flue through the ensuite bathroom that sat above the location of the wood burner stove in the living room. In your case it sounds like it's so both fireplaces in your and your neighbours house can share a single chimney exit, so cheaper for the orignal builder to build one chimney rather than two.

Personally I love wood burning stoves, think twice before removing the flue/chimney because once you take it out its never (or very expensive) to put one back in. 

stuart45

gzoom said:

smpNWI said:

• Why would this be done in the first place? Is there any benefit to this diagonal configuration? Just curious!
  

 so cheaper for the orignal builder to build one chimney rather than two.

I'm not sure that it works out cheaper. Getting the flue to travel that far means setting up the formwork to support the brickwork and cutting a lot of bricks for the angle of the flue. The gain building one stack instead of two depends on how high the stack is. It's the same number of bricks, a bit less lead flashing, a bit less jointing up, and 8 less plumbing points. 

Working_Mum

We had this configuration in our roof (1930's semi in East Yorkshire). We removed all the chimney breasts in our house and had a loft conversion.
We used a structural engineer who gave us fab advice; working with my steels guy and a solid party wall surveyor - I kept my neighbours up to date from the start and they didn't appoint their own PSW. I'm super happy with the reclaimed space I've got in the dining room, my room and the loft. It's made a world of difference.
I'd do a bit more investigating before writing this property off.

smpNWI

Thank you Working_Mum said:

We had this configuration in our roof (1930's semi in East Yorkshire). We removed all the chimney breasts in our house and had a loft conversion.
We used a structural engineer who gave us fab advice; working with my steels guy and a solid party wall surveyor - I kept my neighbours up to date from the start and they didn't appoint their own PSW. I'm super happy with the reclaimed space I've got in the dining room, my room and the loft. It's made a world of difference.
I'd do a bit more investigating before writing this property off.

That sounds fab @Working_Mum!

May I ask how much that added to the conversion bill, roughly speaking? The engineer, surveyor and steels?

Working_Mum

smpNWI said:

May I ask how much that added to the conversion bill, roughly speaking? The engineer, surveyor and steels?

The structural engineer cost me around £500 from memory - we had two projects on the go - opening up the downstairs by removing a wall between the dining area and kitchen plus the loft conversion.

My loft conversion was basically built around a steel frame which was built on site up in the loft (weird access issues). My steels guys charged me £6k for all of the steel work in the loft, plus the removal of the kitchen wall, removal of the rear chimney breasts at ground floor, first floor and loft level. I didn't go and get other quotes so no idea if I could have got it cheaper - I didn't want to use anyone else as this guy has a solid reputation locally (my builder, architect, structural engineer and a couple of clients all said he's the best) as well as being a friend of my ex-fil (small place where I live!).

I downsized to this place whilst still having two adult children at home so I needed to make sure it met all of our needs. I love the space we have created downstairs and the loft conversion means that we each have a bedroom with en-suite. Not the configuration to suit everyone but it does exactly what we need.

Good luck with your project - I hope it comes together for you.

WM