Removing a chimney stack

[jayc89]

We have an old, 2 pot, stack on a gable end. The breast was removed all the way up to the loft level many years ago and it has been left, unsupported, ever since (as far as I know). It's now leaking like a sieve, leaving a pool of water in our wardrobe area whenever it rains...

We had a builder round to price up removing it and making right the roof, they have about a 6 week lead time so I think we need to do something faster.

 

They were talking about putting lintels into the roof space, but I don't know why. Could they be meaning just removing the stack down to roof level and leaving the rest of the stack in place in the loft but supported?

 

Farmer next door has offered us his telehandler and "cage", could I DIY it this weekend?

[markc]

If they mentioned lintels then they are looking at removing the top bit of stack and replacing the roof over but leaving the remainder in the loft.

removing chimney breasts, especially on a gable end can cause a lot of problems because a chimney adds a lot of stiffness and bracing into a gable wall.

[jayc89]

34 minutes ago, markc said:

If they mentioned lintels then they are looking at removing the top bit of stack and replacing the roof over but leaving the remainder in the loft.

removing chimney breasts, especially on a gable end can cause a lot of problems because a chimney adds a lot of stiffness and bracing into a gable wall.

 

Makes sense, so remove some bricks to get a lintel under the rest of the stack, resting on both external walls I presume (approx 4m span), then only remove the bricks above the roof line?

[markc]

6 minutes ago, jayc89 said:

 

Makes sense, so remove some bricks to get a lintel under the rest of the stack, resting on both external walls I presume (approx 4m span), then only remove the bricks above the roof line?

If you can get across to the walls then yes, but often done by spreading the load across several ceiling joist (too often done with only a thin board if anything).

A well supported stack remaining acts like a strong-back for the gable.

Then remove the bricks going through roof line and finish to suit existing

[jayc89]

Decided I'm going to go up and try keep the stack; remove the pots, replace the launching and repoint it, which should hopefully stop the water ingress. And I'll get a builder in to fit a lintel. The thought of it coming crashing down into the ensuite when someone's taking a dip isn't worth considering... 

[Russell griffiths]

Pictures needed

inside and out. 

[jayc89]

35 minutes ago, Russell griffiths said:

Pictures needed

inside and out. 

 

Lead flashing and slipped slates have been fixed since the pic was taken. 

 

[jayc89]

Bit of a naff photo, but shows the left hand side of the stack unsupported in the loft.

 

It's a two pot stack, left side is bone dry, right side is sopping wet internally, so I'm assuming it's the flaunching or pointing letting water in, probably the former given how much water's getting in. 

[markc]

That’s a big heavy stack, what is supporting it at the moment?

[Mr Punter]

Take it down and roof over it.

[jayc89]

21 minutes ago, markc said:

That’s a big heavy stack, what is supporting it at the moment?

 

Not much at all. Possibly a 3x2 ceiling joist that you can just see in the last picture.

 

19 minutes ago, Mr Punter said:

Take it down and roof over it.

 

That was our initial idea, but it would make the gable end look pretty bare and we lose more character from the house. The builder we spoke with suggested we'd need a lintel in the loft space anyway, so we're now thinking - why not patch up the leak, leave the stack, and put that lintel in anyway? 

Edited September 19, 2023 by jayc89

[Mr Punter]

6 minutes ago, jayc89 said:

would make the gable end look pretty bare and we lose more character from the house.

 

No photo of the gable end so we were not fully briefed!  I take your point though.  Chimneys, fireplaces and chimney breasts are often focal and are an attractive part of the character, especially of period houses.  They are also impractical and largely redundant.

[jayc89]

3 minutes ago, Mr Punter said:

 

No photo of the gable end so we were not fully briefed!  I take your point though.  Chimneys, fireplaces and chimney breasts are often focal and are an attractive part of the character, especially of period houses.  They are also impractical and largely redundant.

Oh, I meant to attach this one too, not sure what happened!

 

[ProDave]

What we need is a picture from inside the loft space showing the stack coming down the wall and a close up of how it finishes at the bottom in the loft.

[jayc89]

Managed to get my hands on a tele handler and cage today.

 

The pot above the leak was loose, it just lifted off in my hands and the entire top course of bricks were also loose. All taken down and rebuilt; lime mortar for the brickwork, cement + sika proof mix for the flaunching and refitting the pots. Fingers crossed that stops the leak.

 

Builder coming out to fit a steel beam in the loft to prop the stack up in a couple of weeks. 

[jayc89]

Poured it down overnight. Wardrobe area's looking bone dry this morning. Happy days. Bit of pointing left to finish today, just to tidy it up, hoping the rain holds off for a couple of hours so I can get back up there before I need to give the tele handler back this afternoon. 

[saveasteading]

6 hours ago, jayc89 said:

I need to give the tele handler back this afternoon. 

Maybe too late? I'd make use of the access and have a very close look at the flashings and pointing. Water can get through miniscule gaps especially in windy conditions.

[jayc89]

48 minutes ago, saveasteading said:

Maybe too late? I'd make use of the access and have a very close look at the flashings and pointing. Water can get through miniscule gaps especially in windy conditions.

 

We finished off the pointing this morning. The old lime mortar was just wasting away, so raked a load of that out and put fresh in. There's a load of cement up there too which is causing some bricks to spall, so I need to tackle that at some point, but it was getting pretty windy by lunch time. 

 

We also have a wet verge, which was falling to bits, so replaced that at the same time.

 

Still pretty frustrated we've had 4 roofers come take a look at this leak and none of them spotted these problems. The pot, and cement around it, literally lifted off in my hands without any "encouragement".

[saveasteading]

17 hours ago, jayc89 said:

we've had 4 roofers come take a look at this leak and.

 

As I may have expounded before, roofing is perhaps the easiest job to get away with incompetence. 

It is way up high, difficult to get to and dangerous. So the field of potential roofers is reduced, and few clients will look before or after.

I had one who didn't even know which way to lap felt, or why.

[jayc89]

Just been speaking with an SE who suggested we "might" get away with gallows brackets, but wouldn't elaborate much more than that. The LABC guidelines suggest they should only be used on stacks that aren't fully vertical (ours is) although it does also seemed to be aimed at when they're being taken down below the loft space....) I've dropped our BCO an email to check what he'd accept. 

Given the stack is 15 courses high and the loft space is only 12 and we'd likely need to chop out the majority of them to fit the gallows brackets, I don't think it'll work... 

 

Anyone had joy using gallows brackets recently? 

Edited September 25, 2023 by jayc89

[markc]

Removing more from the bottom is going to give you a top heavy stack rotating around the ridge line. Stick to a lintel at loft floor level if you are keeping the stack

[jayc89]

44 minutes ago, markc said:

Removing more from the bottom is going to give you a top heavy stack rotating around the ridge line. Stick to a lintel at loft floor level if you are keeping the stack

 

That was my thought too, unfortunately. I'll get him out to produce some calcs. 

[saveasteading]

It would be better with gallows brackets than with nothing. SE's specific design would trump the guidelines, whether gallows or lintel or another, so keep talking.