Underside of corbeled chimney breaking away - advice needed

[Neilos]

The house has two internal chimneys that go vertical to the loft, where they are both corbeled and meet at the top to leave the house in a single chimney location on the roof (like an upside down Y).

 

One of the corbeled chimneys (seen below) has the underside breaking away, some of the bricks near the top are loose to the touch. The chimney is fixed to the supporting wall on the far side (the bricks join to the wall, i.e. no gap), there doesn't appear to be cracking on the wall side, I think this is the only reason it hasn't fallen down already.

 

I need advice on regarding:

 

• How safe this is? (do we need to move out?)
• Who do we need to contact to look at this to get it fixed?
• What is the range of pricing for the cost of fixing this?
• What would be involved with fixing this?

 

Many thanks in advance.

 

 

[saveasteading]

That has already been propped up by some very rustic brickwork.

First question....does the chimney stack continue down through the rooms below?

They are often removed (with fireplaces) to make more room space, but without proper replacement support in the loft, this is what would happen.

[Roundtuit]

I'd advise getting a structural engineer to have a look as a first step, and don't touch it until you've had a professional opinion.   It's obviously an old house, and I'd guess the weather coming down the chimney over time has weakened the lime mortar, and the loose bricks are pretty much only holding their own weight up at the moment.

 

You might get away with stitching the crack with helical bars and carefully repointing a bit at a time starting from the bottom to get some integrity back into the stack.

[Neilos]

17 minutes ago, saveasteading said:

First question....does the chimney stack continue down through the rooms below?

They are often removed (with fireplaces) to make more room space, but without proper replacement support in the loft, this is what would happen.

 

I believe that the stacks continue down through the house as there are still large protruding parts of the wall where the stack would be (i.e. the rooms have not been made larger), they're covered with plaster (no gaps for fireplaces) but I assume that the brick is still there underneath.

 

Also I don't think that the crack continues down into the vertical part of the stack, it looks to me as though the underside of the chimney has been pulled away by gravity (probably due to weathering of the lime mortar) and is peeling away from the top.

 

27 minutes ago, saveasteading said:

That has already been propped up by some very rustic brickwork.

Do you think that the central part (under the stack) is added later to support the chimney then? I assumed that this was part of the supporting wall.

 

It might be worth noting that this is a semi detached house and the neighbour has an identical chimney setup on the other side, so the central blob of rustic brickwork actually sits underneath 4 chimney stacks. I have no idea what this looks like from the other side.

21 minutes ago, Roundtuit said:

and don't touch it until you've had a professional opinion

I'm not going to fix it myself.

 

22 minutes ago, Roundtuit said:

You might get away with stitching the crack with helical bars

This would be good as it would cause the least disruption but I guess we need to get a structural engineer out to look at it first hand, fingers crossed we don't need to undertake major work to get it fixed.

 

24 minutes ago, Roundtuit said:

I'd guess the weather coming down the chimney over time has weakened the lime mortar

I'll take a look at the weather proofing on the chimney, it might need to be improved.

[markc]

Doesnt need an SE to say that is in a very bad state and well on its wall to falling. It needs sorting ASAP. If it was mine i would add temp prop supports to prevent it falling.

[PeterW]

7 minutes ago, markc said:

Doesnt need an SE to say that is in a very bad state and well on its wall to falling. It needs sorting ASAP. If it was mine i would add temp prop supports to prevent it falling.

+1 to this and speak to your insurance company. 
 

Get some decent pieces of plywood - thicker the better - and get them laid under the chimney area so if the bricks do fail they hit the ply not the ceiling below.  

[saveasteading]

I had misread the perspective of the photo, and thought that rough brick was under the corbelled stack. Thanks to your reply I can see that it is part of the party wall, which looks very rough work indeed., with too much mortar. I would have your Engineer look at that too, as a precaution.

 

Agreed an Engineer has to look at this.

There may be a solution using a standard component that is utilised when a chimney is removed beneath. I fitted one when I realised that my daughter's house had the chimney sitting on the wood of the ceiling. Building control were helpful too, as they have seen this before.

So common an issue  that the parts are at screwfix , but specialist suppliers online have more choice.

Search for 'chimney gallows brackets'.

 

It took me (Drill, bolting and quality control, and holding) and a bricklayer about 2 hours to fit the brackets , and then patch up the bricks. Yours perhaps 4 hours, including reoving and rebuilding the loose bricks?

But context and site inspection is crucial, and a Structural Engineer will give the best advice.

good luck...it should be ok as noticed in time.

 

It would be good if your neighbour looked at their side too. You are jointly  holding up the same great lump of brickwork on the roof.

[Roundtuit]

15 minutes ago, markc said:

Doesnt need an SE to say that is in a very bad state and well on its wall to falling. It needs sorting ASAP. If it was mine i would add temp prop supports to prevent it falling.

Clearly, but it needs an SE to assess the risk and propose a solution. Personally, I'd be wary of touching it until its been looked at.  If you attempt to add props and anything goes wrong it could perhaps be seen as an attempt to repair and complicate any insurance claim. 

 

Good idea to protect the ceiling with ply.

[Neilos]

Structural Engineer came out a few days ago. He thinks that a temp "A" frame between the stacks will hold it while helical bars are added and the whole thing repointed. He says that it doesn't look to be water damage and thinks that it's just time and gravity that has caused it to break away (the building is almost 150 years old - 1876). He also said that it is not in imminent danger of falling as it is being held by the rest of the brick work, the chimney stacks have not been removed in the rooms below and the rough brickwork in the middle is actually providing support.

 

So, it looks to be best case scenario - just need to book a builder now, they're all booked up :/

[Neilos]

Another interesting point the SE told me about was to notice where the cracks have formed, they (mostly) formed along a path where the original builders used small cuts to fill gaps, he said that if the original builders had planned it a bit better then they would not have had to use small cuts and could have made it wholly from full bricks which would have provided a better structure, so there is a lesson to be learned here - well I'm learning a lot anyway!