Chimney removal query

[mbaldwin]

Hi all,
I have a renovated single fronted brick Victorian. The dividing wall between the front two rooms and most of the corridor wall has been removed, leaving a fireplace and chimney (roughly 1500 x 2000) sitting smack in the middle of the living area.
To add insult to injury, a mezzanine floor has been put into the roof space as the master bed, and the chimney runs right through the middle of this also.
The chimney does carry some roof beams, but they should be able to be supported with some better positioned vertical supports.

Question is, I am pretty sure having a free standing chimney like this must be a bit unsafe...who would I go to who might be able to certify that?
Otherwise removal of the chimney might prove troublesome from a planning perspective...apparently I can do what I like inside, but I'd have to leave the chimney stack poking out of the roof as I'm in a heritage overlay area.
Any ideas?

[pawnhead]

Hmmm.

It sounds like some hack has taken to the place with a sledge hammer, with no consideration for the integrity of the structure as a whole. It's not true that you can do 'anything you want' inside a house. You can put up non-load bearing partition walls, and you can remove non-load bearing partition walls (without council approval), but if you don't know the difference, then it's best not to touch anything. Even if a wall is not (vertically) load bearing, it could be serving as a brace (taking lateral loads) for the structure as a whole, especially with brick walls in a masonry construction. You can't just pull out half the walls even if you install the proper beams to support the structure. A strong wind could blow the whole structure over if you haven't left enough walls to brace up the building.

If you can you post up some pictures, I might be able to give you some idea. I'm a builder with some engineering knowledge and experience, but I'm not a structural engineer. It might be wise to get an engineer in to have a look at it, and certify it, just to make sure that it's not going to collapse in a storm.

[mbaldwin]

Thanks pawnhead,
Here are some snaps from a few months ago...I can certainly show you something more specific but this gives you the general idea, showing the fireplace and remaining corridor wall in the living room, and the chimney going through the bedroom also.
Interestingly, the remaining corridor wall is not load bearing...it does no go all thw way to the roof/ceiling, so I presume it is serving as a lateral brace as you suggest.

http://www.markbaldwin.com.au/images...e/IMGP2570.jpg
http://www.markbaldwin.com.au/images...e/IMGP2584.jpg
http://www.markbaldwin.com.au/images...e/IMGP2586.jpg
http://www.markbaldwin.com.au/images...e/IMGP2590.jpg

[pawnhead]

Thanks pawnhead,
Here are some snaps from a few months ago...I can certainly show you something more specific but this gives you the general idea, showing the fireplace and remaining corridor wall in the living room, and the chimney going through the bedroom also.

Yeh, that looks just like what you described in your last post. It looks like there used to be a small room in the front, and a hallway from the front door. I’ve worked on quite a few old terraces with similar original floor plans. It’s more than likely built using lime mortar which isn’t nearly as strong as the cement mortar that’s used nowadays. It looks like they’ve re pointed the brick chimney with cement mortar after they knocked down the walls and stripped the plaster off it.

Interestingly, the remaining corridor wall is not load bearing...it does no go all thw way to the roof/ceiling, so I presume it is serving as a lateral brace as you suggest.
http://www.markbaldwin.com.au/images...e/IMGP2570.jpg
http://www.markbaldwin.com.au/images...e/IMGP2584.jpg
http://www.markbaldwin.com.au/images...e/IMGP2586.jpg
http://www.markbaldwin.com.au/images...e/IMGP2590.jpg

It would help to stiffen the front wall with the door opening in it so I’m glad they didn’t remove that part as well whilst they were at it, but it’s not a major structural bracing wall. The major bracing in that direction would be provided by the dividing (used to be 'parapet') wall between the two terraces. I can see that they’ve (probably) removed the dividing wall upstairs as well (since from the outside photo, there's an opening window sash right in the middle of where it used to be), and created an arched opening downstairs between the two terraces. The downstairs pic is obviously of the South-Western? terrace (judging by the midday sun in Melbourne) and the upstairs pic is of the North-Eastern? terrace. The wall they’ve removed from adjacent to the fireplace downstairs would have provided a significant amount of bracing to the South-Western? external wall which is quite a substantial and high 11” thick masonry wall. I’d be a bit concerned about that.
I’d say that if an engineer looked at it, he’d want to satisfy himself that that external wall was tied back to the rest of the structure to prevent it toppling outwards. There would be several ways of achieving this, possibly involving long tie bolts with a plate on the outside of the wall, and the bolt extending right through to the other side of the house. Or possibly by installing a steel beam in the ceiling/upper floor, tied back to the structure somehow.
He’d have to look at the possibilities a bit closer before forming an opinion.
One thing is for sure. Those walls should not have been removed without an engineers approval, and if anything happens to the structure, then I don’t know what your insurance company would say about it (or your SWMBO if she ends up buried in bricks).

As far as the chimney goes, if the structure is deemed safe, then you could possibly remove it and after installing sufficient support, you may be able to construct a 'dummy' light weight chimney just sitting on top of the roof, made out of blue board, and a good plasterer could make it look like the old one. I don't know what the council would say about that though.

edit: - I can't stress enough that people shouldn't just go knocking out walls if they don't know what they're doing. The front wall doesn't provide a whole lot of bracing in that direction because it has a door and a window opening in it. If you go removing walls inside without proper engineering, then the place (probably built with weak lime mortar) could fall over like a row of dominoes.

[mbaldwin]

Thanks again pawnhead,
Both shots are of the western 'half'...there's an identical row of windows looking out the back of the upstairs. Otherwise you're bang on. Obviously I need a structural engineer first and foremost.
I had already asked about a mock chimney stack...council want a planning permit. It would be ok to leave the original stack outside the roof (...supported how???), even take it out for a while and put it back, but not to replace it with anything, no matter how close to original it might be.

[pawnhead]

Thanks again pawnhead,
Both shots are of the western 'half'...there's an identical row of windows looking out the back of the upstairs. Otherwise you're bang on.

I was thinking of that possibility but since I noticed that they were joined together I just assumed that it was next door at the front.

Having a closer look at the pics, it looks like the whole upstairs roof has been lifted from its original lines to form your mezzanine level. Those windows have obviously been added later since they don't match the style of the period, the rafters look too new to have been existing, the middle parapet wall would have originally extended up past the original roof line, and from the outside it looks like they've added more height to the two end parapet walls since they seem to be unpainted. They've pitched the new rafters straight off the window frame as well. At least they've put each one over a mullion.
With the central dividing wall gone from upstairs (I'm assuming that there's none of it left up there), then the ridge would be spanning between the chimneys in the middle and the chimneys and the outside walls, so you'd be right in assuming that they're helping to carry the roof at the moment. Of course you could get rid of them if you've got very deep pockets, because it wouldn't be cheap I assure you.

Obviously I need a structural engineer first and foremost.

I'd definitely advise that just to make sure the structure is safe, but he'd be able to design something that would carry your roof, and you could rebuild the top of your chimneys on it in masonry as per the original specs. It would involve a couple of dirty big steel beams that would have to span from one external wall right across to the other external wall (since the middle wall is gone now). They'd have to be strong enough to carry the roof, and all the bricks in the chimney above. There'd have to be at least four more steel beams gong in between the first two to lay the bricks on and tie it all together, and probably one at each end to lock them together nice and tight. He'd probably say that the old lime mortar external walls wouldn't carry the weight, so you'd have to brace them up (temporarily) and cut four slots in them so you could install a steel post under each end of the two big beams in the roof, and of course you'd have to rip a hole in the upstairs and downstairs floor so you could get the posts in and dig a footing down to rock under each post, which you'd have to pour some concrete in before installing all the steel with a big crane. Then you could think about patching up all the holes you've cut, and rebuilding the chimneys. It's probably easier to just rip the existing roof off to do it as well. It would be a hassle to leave it there and prop it up whilst you cut the guts out of it to install the steel.
The good news is that he'd design the posts to be connected to that outside wall that's a bit dodgy now since the downstairs walls have been removed. The bad news is that you'd still need some sort of lateral bracing in that direction so I hope there's some internal walls left downstairs that he can attach it to somehow. A couple more steel beams in the floor should do the trick.
So after forking out a good five or ten grand or more to keep him happy with all his drawings and inspections and certification BS, you'll only have to spend another fifty or a hundred more to keep your builder happy.
Of course it's a lot cheaper if you just keep the chimneys there and rebuild the bottom walls that were ripped out, but he might come up with an easy solution to leave the bottom walls out if he has a look at it. As I've said, he might just suggest some tie bolts extending through the outside of the wall with a plate on the outside to restrain the wall. He might even say that it's safe as it is but I doubt it. They usually like to cover their @rse and make some money out of you at the same time if they're going to sign off on the place.

Sorry about the bad news, but that's just my take on it.

Good luck.