Guidance on how to support chimney stack pls

[Ady88]

Hi,

I am trying to remove my chimney from ceiling level in the loft down to the ground floor.

I'm not sure how best to support the stack so I can remove the breast.

Would I use acro props to hold the bricks while I install steel gallows and lintel? Will a timber lintel do it? As there are only a few courses on roof level and next summer I hope to have the stack removed while scaffolding is up for dormers.

Please offer any guidance you can, I tried searching the forums but mine seems to be more of a specific case. I have attached photos.

I started removing some of it to inspect it.

 

[conny]

I haven't a clue as to how you would go about this, but just out of curiosity. Is your chimney stack shared with a neighbour?

 

[Ady88]

Thanks for the reply still, nope my house is an end terrace and the stack is on the end of the terrace so only resting on my wall.

 

[cdbe]

Does the right hand purlin continue into the gable wall?

Assuming it does, if you picture your (concrete) lintel going across and into the front face of the brickwork, effectively replacing a full row of bricks, and picture you removing that row of bricks - the brickwork above will be adequately support by the remaining brickwork at either side till you get the lintel and gallows brackets in place.

Or it would, were it not for the fact that someone has removed a big chunk of brickwork from the left hand side, I can't quite tell how far back this has gone but anything more than the width of the lintel (100mm) needs temporarily reinstating.

Although I'm not advising, I've propped a few where most of the external stack was gone using a timber hung from the two adjacent purlins and they're still up.

 

[Ady88]

Thanks for the advice!

Yes the oak purlins either side of the chimney breast go into the gable end wall. The space between them is approx 1600mm.

I had been thinking of a similar principle to what you have used before. I was thinking of getting 225mm joist and running it against the chimney breast in between the purlins. Then running concrete screws into every other brick so the timber joist acts as a plate to carry the bricks and push the load into the purlins while I remove bricks underneath to install a concrete lintel and gallows bracket. This should work?

I'm hoping to take the stack out in future when scaffolding is up for the roof work so I need to support it adequately for now.

Btw i removed the few bricks on the left to see how the chimney stack was built but I can temporarily rebuild to install the lintel.

 

[cdbe]

Yes. Doesn't really need much.

I think the drawing illustrates.

 

[Ady88]

Yep that drawing shows it clearly.

My problem is that the stack isn't deep enough at the point where I want to support it because the chimney breast slims into the gable wall.

It looks like it is only 225mm so one brick length away from the wall. But I think I understand what you mean now. As long as there is support either end of half brick width then I can remove the facing bricks to slide in a lintel.

I will take another look at it and maybe take some more photos

 

[Ady88]

Don't know if this photo is clear enough, it shows there is only 1 brick course and behind it is the chimney cavity. In the centre you can see the half bricks.. these are running the other way into the protruding chimney stack supporting walls so I guess these are supporting the course of facing bricks?

 

[blup]

Do you have a pic of the flue/ stack externally?

Blup

 

[Ady88]

Hi, yes one angle is from the side and other from the front. There are about three courses for the stack

 

[George_engineer]

The cost of steel work and propping will be more than getting a tower scaffold and taking it down starting at the top.

Gallows brackets wouldn't be suitable here as it's end terrace and using roof timbers to cobble something together isn't recommended.

Also if you want to partially remove a chimney breast with supports for the remains then it is structural work required building regs and possibly the input of an engineer.

 

[Ady88]

Thanks for your input, I am hoping to get scaffolding for the full house in spring to add a flat roof dormer to the rear and at that point I intend to remove the stack as well.

Currently I wanted to remove as many bricks internally as possible so I can make some progress on the internal work.

Building regs will be involved and I'm sure they will only sign off once the stack has been removed and new roof put on.

ATM I'm looking to support just the 3 courses of the stack and a few courses I intend to leave on the inside.