[?] Removing lower part of disused chimney.

[David Chapman]

Hello,

We will soon be having a conservatory added to the rear of our house.

In order to provide a 'smooth' rear wall surface it will be necessary to remove the bottom five feet (or so) of a disused brick-built chimney projection (51cm wide and projecting 24cm) that used to carry the flue from a (now removed) kitchen, and the wall then made good. The bottom of the chimney tapers into the wall at head height.

I'd be most grateful to receive any suggestions/advice about how to make sure that this job is done correctly, and what form of structural support, if any, will be necessary for the remaining upper part of the chimney.

I'm certainly NOT planning to do this myself since the job is well outside my own DIY 'comfort zone'. Once I have fully understood the possible problems I'll ask two or three local (to Bromley, Kent) well-established builders to come along and quote for the job. Anyone interested?

Many thanks,

- Dave

[Bruce]

The first thing you should do is get a structural engineer to survey the structure and draw up plans for how the work should be carried out. Then, and only then, should you get your three builders to quote for the work.

[JimK]

even if you have a multiple storey house it would probably make more sense aesthetically at least to take the whole thing down? wouldn;'t it look a bit odd when looking up from the conservatory to see the remains of a chimney dangling there? never mind the potential for it to eventually fall and smash the roof in?

cheers JimK

[RobertL]

i agree, define what is to be done, then get quotes for it. Don't forget to keep Building Control informed of course.

Robert

[JimK]

or avoid all that bollox and use the "professhunal's" fees that Bruce wants you to spend on paying more to a good builder to take the lot down...

JimK

[JimK]

make it a part of your contract with the builder to obtain all necessary consents etc including the BCO?

JimK

[Jim]

It's an interesting question of aesthetics - sometimes losing the chimney stack on a gable end will make a house look "wrong" or unbalanced.

He will also possibly end up exposing an area of unsightly brick covered in tar and brick ends which will need to be dealt with.

[Peter Andrews]

I'm not clear from your post - does your chiney do this:

! ! ! ! !\ ! \ ! \ ! \ ! ! ! ! ! !

-----------------------------

or this?

! ! ! ! ! ! ! ! ! ! ! ! ! ! ! / ! / ! / !/ ! ! ! ! ! !-----------------------

Peter

[Alan Braggins]

[...]

I think "The bottom of the chimney tapers into the wall at head height" means there won't be anything dangling, and taking the rest of it out and making the wall good would be a lot more work.

[dom]

Can you tell if the chimney is part of the original construction of the building?

If it's an add-on, definitely take the whole thing out.

If it's original, it may be very difficult to find sufficient support at a higher point on the building, without adding a lot of new masonry.

Would it be feasible to build out either side of the chimney at ground level, to achieve a flat wall that way - by addition rather than subtraction?

Any idea *why* it was built this way - it's a lot of trouble to go to

- architectural feature/local vernacular?

[Bruce]

So on that basis, the fact that you cannot see the chimney stack above head height would mean that it didn't exist, didn't need to be supported and the OP didn't need to worry about it falling down.

Out of sight, out of mind, eh?

If the chimney stopped at head height, where did the flue gases go? Disappeared into the brickwork, presumably?

I hope the OP realises that this job is far too important (and safety critical) to be entrusted to amateurs dispensing "expert" advice on newsgroups. It is also too important to be trusted to most builders - I have seen some real horrors left behind when builders were employed rather than consult a structural engineer at the outset.

There are many DIY jobs where the advice given on newsgroups like this here is correct and can be quite valuable. There are many DIY jobs where the advice of a professional is not required, and where others' experience is a useful guide. But partial removal of a chimney stack definitely isn't one of them.

However, it seems there is no shortage of smug and complacent people who are quite prepared to disagree, and routinely offer negligent "advice" in areas where they are almost completely ignorant.

[The Natural Philosopher]

Seconded.

Don't mess around. couple of hundred quid for a proper report that will keep builders happy, BCO happy, insurance company happy. And anyone whoo may one day want to buy..

[Roger Chapman]

snip

So you think the external chimney on the ground floor provides meaningful support to the internal chimney on the first floor? It is possible that the external chimney performs a valuable function as a buttress preventing the wall from buckling outwards but it cannot give any direct support to the internal chimney upstairs. Ergo the upstairs chimney is already supported and consideration needs to be given to the stability of the wall without a buttress to support it.

FWIW the end result of taking out the buttress is directly comparable with the removal of the bottom part of an internal chimney with the remains supported by a gallows bracket.

I presume that there is another fireplace upstairs and a twin internal flue thereafter. I can't see much point in tapering it into the brickwork if not, but it could be a single flue all the way to the chimney pot. The architect finding the effect aesthetically pleasing or just not so concerned with wasted space upstairs as he was with the kitchen.

As it happens the OP isn't planning on doing the job himself. If it was me I would have no hesitation in doing it myself.

I could be wrong but from the dimensions given it appears that the downstairs chimney is some 20 inches square with a flue approximately 10 inches square within. If the flue is square then there is no room for a cavity at this point so the building work would have to consist of demolishing the external structure and reconstructing the outside leaf. Hopefully with salvaged bricks from the demolition and, just as hopefully, without the need to rebuilt any of the inner leaf.

That is what we are here for after all and all our advice is there to be taken with a spoonful of salt, particularly when it contains earnest entreaties to rely on the professionals.

[Bruce]

More to the point, it will keep the OP happy, because he will not have to worry about several tons of masonry crashing down at some point in the future, causing damage to people and property.

Thanks, by the way. ;-)

[JimK]

eh? if the bottom of the chiimney tapers into the wall at head height and the OP removes 5ft of it (NB upward) what is now 5ft above where the bottom used to taper into the wall? Answer: the bottom of the remainder of the stack? no?

JimK

[JimK]

birds of a feather...

[David Chapman]

Many thanks to all those who took the time to respond to my posting. I seem to have stirred up quite a hornet's nest ;-)

Anyway, since a picture or two always help to explain a problem much better than words, let me invite anyone who'd like to see the chimney and is still interested in reading and/or commenting to check out:-

BTW, this chimney is integral with the (1930s) house and was ONLY ever used by the kitchen boiler which has now been re-sited. There are no other fireplaces feeding to it.

Thanks again for all of your interesting recommendations.

- Dave

[Roger Chapman]

I seems I got it the wrong way round again. Sorry about that. (Must look more closely at what is actually written next time).

But that actually makes it a much simpler job to complete. All your builder needed to do is recreate the taper further up the stack and make good below if you don't want it taken out completely.

[JimK]

nah normal service ;>)

aha - seems I guessed correct ;>)

OK, and as it's all rendered and has only been used for a boiler I would still expect no mega issues in removing it (subject to BCO if you're nervous) and successfully hiding any "scars" afterwards with render to match.

No probs

Wildcard:- if the stack would suit - how about *extending* & lining the stack (with the correct flexible flue liner and installing a small woodburner at the base within your conserv?? keep the heating bills down in winter if you plan to use it /or/ keep your orchids/whatever alive come the next global warming winter!!

Cheers JimK

[Bruce]

Only an arrogant person would make any definitive statements without having seen the situation personally.

Rule No.1: Don't ever presume.