Raising Chimney

DavidJonas

We are gradually rolling forward on our plans for a double storey side extension. Very gradually actually. Anyway, it means knocking down the garage and erecting the two storeys there, taking the house sideways. Our house is a 50s semi.

There is a small chimney stack which runs up the side of the house. Don't know what it is doing there as no other houses down the road seem to have one but it was there when we moved in last year and does not appear new. The bottom of the stack is in the garage.

I thought it would be nice to keep this and install a liner and wood burning stove in the room we are planning there. Would make for a nice cosy feature.

What only just occurred to me is that if we extend the roof sideways as intended, the chimney will end up inside it! A flat roof not an option as would be totally out of place in this road.

Is it easy to raise the height of a chimney? If so do we need planning permission for this feature. Also, is it wise? It looks kind of spindly as it is.

rustyboy21

Speak to your builder, he will have experience over things like this.

You should be able to increase the height of it, if you are going to line it for a stove, then it is more of a cosmetic and structural thing, rather than a useable thing, as the liner will take over the work of the chimney used to have.

Being in the middle of the roof won't be an issue, It is the same as where chimney stacks are in semi detached properties

cyclonebri1

As above really, the stack location, on what was the gable end is exactly the same as any other roof.

The bit I don't understand is this. You say you need to extend it?

It's already above the height of your 2 story home I assume, you are extending the same height?

So why does it have to go higher than present?


When alls done, just ensure a function test is carried out and certified with the fire installation.

There is another issue you need to be aware of. I can only assume that as you say the bottom of the stack is in the garage at present that that's the back of the stack, not the fire opening.

You need to check where the actual void of the stack is, it's likely deeper into the house than you thing, and you really will have to check the thickness and how the original internal fire opening was closed,

Yes a lot of assumptions, but trying to 2nd guess any issues.

DavidJonas

Many thanks for your input.

The roof right now is hipped. The ridge goes out horizontally away from the party wall (where the main chimney is) and then comes down in a hip to the other end of the roof. Right there where the hip comes down to the guttering on the side is where the second chimney is. Bang in the middle of the side wall. Running up alongside the outside of the house. So the chimney doesn't even go into the roof at the moment. The guttering runs around it.

In order for the roof to match the other houses in the street, even the neighbours, the ridge will have to be extended and the hip moved further along so that it comes down to meet where the new outside wall will be, some 3 metres further along.

Just looking at it and comparing it to next door I can see that the extended ridge will come out to about where the second chimney is now, and the second chimney does not even go up that high.

Sorry if this isn't clear, but that's why it needs to go up I think. Because otherwise it will terminate in the roof space of the extension.

But really the roof will just have to flow around it.

It's quite odd, the hole in the bottom of the chimney does indeed come out into the garage. It doesn't come into the house. That's where the stairs are. I guess it could form more of the wall it is on than I think, but it doesn't intrude into the actual house. And it is just open, and at chest height, supported by a concrete slab built into the adjacent wall.

Why someone would want a chimney in the garage I don't know.

But if I can elevate it without planning permission that will be good. I can just do that when needed.

Furts

Get some careful advice before raising the chimney. Both on the existing stability and strength, plus the state of repair.

Many are built so they stay in place but I would suggest are on the limits of stability. Some are so tall and spindly that I view them as suspect. They remain in place provided the mortar has not eroded , or weathered, the internal mortar not been attacked or degraded, and the winds are not too strong!

I have seen others where satelite and TV aerials have weakened them.

cyclonebri1

DavidJonas wrote: »

Many thanks for your input.

The roof right now is hipped. The ridge goes out horizontally away from the party wall (where the main chimney is) and then comes down in a hip to the other end of the roof. Right there where the hip comes down to the guttering on the side is where the second chimney is. Bang in the middle of the side wall. Running up alongside the outside of the house. So the chimney doesn't even go into the roof at the moment. The guttering runs around it.

In order for the roof to match the other houses in the street, even the neighbours, the ridge will have to be extended and the hip moved further along so that it comes down to meet where the new outside wall will be, some 3 metres further along.

Just looking at it and comparing it to next door I can see that the extended ridge will come out to about where the second chimney is now, and the second chimney does not even go up that high.

Sorry if this isn't clear, but that's why it needs to go up I think. Because otherwise it will terminate in the roof space of the extension.

But really the roof will just have to flow around it.

It's quite odd, the hole in the bottom of the chimney does indeed come out into the garage. It doesn't come into the house. That's where the stairs are. I guess it could form more of the wall it is on than I think, but it doesn't intrude into the actual house. And it is just open, and at chest height, supported by a concrete slab built into the adjacent wall.

Why someone would want a chimney in the garage I don't know.

But if I can elevate it without planning permission that will be good. I can just do that when needed.

Ok, I think I have it now, this is where a pic or sketch would have pai.......ds.

Wrongly I assumed a gable end not a hip, (slap on the head with wet kipper), now understand the raising issue.

You can't understand why there was a fire place, (in effect), in the garage?, why not, how many garages are used to house cars?

It could have been to house a classic car, be a hobby room, or even a very basic grandad flat, wanabee drug dealer even.
Anyway someone wanted to heat it.


Your concerns about the stability are well founded, considering it will be unsupported for a lot higher than it is now..

Thinking blind here, the roof is hipped, you are extending and the roof will be hipped at thye end?

What's to stop you extending the end wall upward along with the existing stack, giving all the stability needed.

Sorry, don't do drawings on here, but you or someone will know what I mean

DavidJonas

Thanks again. That is good advice.

I didn't think about building up the outside wall to support the increased height. I will raise that with the builders when the time comes. Happier now that I think it can be done, as didn't want to get to the point where I say "how do we do that" and we end up scratching our heads !

Gloomendoom

cyclonebri1 wrote: »

You can't understand why there was a fire place, (in effect), in the garage?, why not, how many garages are used to house cars?

I would have thought a heating boiler of some kind would have been more likely.

I broached the subject of raising a chimney stack to my local building control who told me that it would need planning permission. Their building regs chap also said that he would need proof that the existing structure could cope with the extra loadings.

I didn't bother in the end.

vaio

As the chimney will need lining anyway could you not leave the brickwork as is and run the new liner up the chimney, into the new loft space and then out through the roof?

cyclonebri1

DavidJonas wrote: »

Thanks again. That is good advice.

I didn't think about building up the outside wall to support the increased height. I will raise that with the builders when the time comes. Happier now that I think it can be done, as didn't want to get to the point where I say "how do we do that" and we end up scratching our heads !

Yep, there is also the issue of the ridge being man enough, given it is being extended from the hip, not the gable as I thought, raising the wall provides support for this too.;)