Another chimney breast question

[jayc89]

We have a detached house, with a double chimney breast on each side of a hip roof. All have been capped and are no longer used. To retain the original look of the property, we don't want to remove the stacks above the roof, but the breasts in the ground/first floor rooms are taking up space, are a damp risk, without suitable (uncontrolled) ventilation, and complicate our internal wall insulation plans. As such, I'm considering removing the breasts in the rooms, leaving the stack coming through the roof in place. 

 

Given the stack is not tied into the external walls beyond the wall plate, any support within the loft would effectively leave the stack balancing on it. The stack also dog-legs out half way up the first floor rooms, so there can't be many tied in bricks supporting the stack above the roof nor can the base of the ground floor breast be supporting the entire load.

 

Is there a standard way of removing breasts below a stack that dog-legs out like this in a hipped roof? If it was a gable end, and being detached, a set of gallows brackets would work fine, but given there's no brickwork in the loft space to anchor them too, I can't think of an obvious way of achieving this.

 

The roof joists run parallel to the stacks. 

 

I'd speak with a Structural Engineer prior to doing any work, I'm not that maverick, but before I do, I'm looking for a sanity check that 1) this is possible and 2) won't cost a fortune. 

[nod]

Gallow brackets are a thing of the past and will not go through Buiding control 

You will have to take it all out Or live with it 

[PeterW]

Remove the lot - if you take out below you’ll lose all structural integrity.

[Nickfromwales]

25 minutes ago, PeterW said:

Remove the lot - if you take out below you’ll lose all structural integrity.

+1

1 hour ago, nod said:

Gallow brackets are a thing of the past and will not go through Building control 

Good to know, thanks!

[jayc89]

Is there no other option than to tear it all down? I think I'd prefer to leave the chimney breasts in place than do that.

 

I assume any RSJs would need to be low enough down the wall to support the stack where it's tied into the external wall, so would result in some level of boxing-in in the upstairs rooms? I assume this would be safer to do in the first floor joist cavity, so we could at least remove the breast on the ground floor?

[pilgrim]

2 hours ago, nod said:

Gallow brackets are a thing of the past and will not go through Buiding control 

You will have to take it all out Or live with it 

My building control inspector told me to install gallows brackets when I removed my chimney breast earlier this year, and has signed off the install.

 

In this situation it sounds like you would need to remove it all and then maybe install a lightweight decorative chimney stack on the roof if you want to keep the same aesthetic.

[PeterW]

7 hours ago, pilgrim said:

My building control inspector told me to install gallows brackets when I removed my chimney breast earlier this year, and has signed off the install.

For a mid building  chimney you may get away with it - ie one on an internal wall - but for external walls, gables and especially freestanding stacks then you need to retain structural integrity lower in the building to counter the turning moment of the exposed brickwork.

 

In this instance you could insert steel lower such as in the first floor subject to calcs/survey and free up the ground floor space but it’s a lot of hassle to retain something just for looks