Reducing chimney stack hight

[Pemu]

There's a chimney stack on the party wall in the back room of Victorian terrace. Previous owners on both sides removed the breast and there are a few courses of brick in either loft. Perhaps 10 courses below the roofline and about 15 above so seems very too heavy.

 

I was wondering if it would help to get up there, knock off about 10-12 courses and seal it up until time and finances allow a proper removal and patching of roof.

 

Neither property is using the chimney for anything and neighbour is happy for it to be removed but can't afford to contribute anything ATM. 

 

 

Edited July 29 by Pemu

[saveasteading]

Knocked out chimney breasts is a scary thing. Do these people have no idea?

I've seen a chimney hanging on nothing but the half brick party wall and a ceiling.  We built in support using the brackets made for the purpose and got bco approval.

How many other houses have the same?

 

I'm inclined to keep the chimney and support it.

 

 

 

[Pemu]

Yep, but the cost and hassle of internally putting in brackets/beams and all the mess that will cause is beyond anyones budget and tolerance threshold. Therefore, removing the majority of the stack from on top seemed like a good half way house until we can get a roofer in to do the rest properly. Some of the neighbours have done the same.

[Mr Punter]

44 minutes ago, saveasteading said:

We built in support using the brackets made for the purpose and got bco approval.

 

It is worth noting that in many circumstances, installing a gallows bracket will not be satisfactory.  Factors such as neighbouring chimney removal, wall thickness and height have an impact.  Often a Structural Engineer will need to be involved.  Corbelled brickwork alone is a no-no.

[saveasteading]

3 hours ago, Mr Punter said:

Often a Structural Engineer will need to be involved.  

Yes that or a real possibility of the chimney collapsing. 

Although i am that Engineer I still wanted the bco to agree.

The local bco is probably able to advise as it will likely be a common thing in your area.

[George]

I'd keep things as they are until you can do the thing properly. Removing half may destabilise it. 

[Gus Potter]

On 29/08/2024 at 14:14, George said:

I'd keep things as they are until you can do the thing properly. Removing half may destabilise it. 

You may ask what is @George on about.. ? to the lay person it may seem odd that when you remove load from a brick wall it can make it unstable. How does that happen?

 

Imagine you have a brick wall 2.4m~ (8 feet high) That's about in old money 32 courses of brick. The mortar is old so not "sticky" thus it can only carry a downwards load. Envisage 32 bricks stacked up on old crappy mortar.. if you can.

 

Now the wall is held in place by the floor and the ceiling at the top and above that by the rafters say. . Imagine if you gave it a sideways push.. ? For it to topple (basically) you would just need to over come the self weight of the bricks that are left for the wall to bend beyond it's "sideways tipping point" . But the chimney stack adds more weight which makes it harder to topple.

 

You can try this at home with say Jenga blocks. Add weight to the top of a stack of blocks and they are harder to topple when you push sideways.

 

Also if you remove one side of a chimney and use gallow brackets you can suddenly make things a lot worse as the gallow brackets cause a "toppling force" that is unexpected.. that is why for one reason BC have clamped down on this.

 

 

 

 

 

 

 

 

[Gus Potter]

On 29/07/2024 at 08:51, Pemu said:

Some of the neighbours have done the same.

Ask what would you home insurance say! Do you think they would pay out if your only arguement was.. well other folk have done it? Builders often tell you what you want to hear not what you need to know.