Fireplace Woes

Hi all,
I have been lurking on this group for some time, but this is the first time that I have ventured a post of my own. I have been using the holidays to do a spot of DIY (redoing the kitchen), but (as usual) I have encountered a problem which is beyond my abilities.
I removed the plaster from a wall in my kitchen as it was in poor shape. I was planning to insulate and dry-line the wall instead. But behind the plaster I discovered an old fireplace which had been sloppily bricked-up, and also a large crack running up the line of the chimney. It appears that the crack had simply been plastered over at some time in the past 20 years (my estimate). I don't simply want to dry-line over the fireplace and crack as it doesn't look in particularly good shape. But I am rather unsure what to do about the problem. I have put a photo of the crack and fireplace at the following location (apologies for the poor quality):
http://homepages.inf.ed.ac.uk/cdw/images/wall.jpg
The top of the picture shows the remnants of plaster that I haven't yet removed (covered by some rather hideous wallpaper)! The crack runs down the left hand side of the picture (it is around 5cm wide in places and around 2m in length). The wall is constructed of stone and lime mortar, and the bricks and breeze-blocks at the bottom of the picture are covering the old fireplace.
I think the problem is that the fireplace doesn't have a proper lintel, and this has caused the wall to sag and the crack to form, but this is just a guess. Does anyone have any suggestions as to how I fix the problem, or even who I should contact to assess the problem? It is a ground-floor Victorian-era flat with 3 similar flats above. Any suggestions appreciated, and a happy new year to all!
Chris
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And in the estimated 20 years since the crack was first covered over with plaster, has the crack ever appeared through the plaster covering?
The fireplace looks to have the older bricks across the top which used to hold the fire opening in place by forming a slight arch, rather than a solid lintel as used today. This has sagged slightly on to the top of the new in fill by only an inch or so. This has probably happened because of a weak mortar mix allowing the new brickwork to settle to much for the situation, and the fact that the side support where the crack has appeared has been removed a bit to far from underneath the arch when the old fire was lifted out.
If, in the 20 years or so estimate you say, the crack has never appeared to open any more than what you can see now, then the stonework has settled to the point of complete rigidity again and it probably won't move any more if left well alone.
The crack, especially one that size, would most certainly have shown through the plaster long ago if the chimney breast was still on the move. The crack has also appeared only on the facing of the stonework that forms the chimney breast and fire opening, and not in the actual structural wall that it's built against, so you shouldn't have any problems with flooring weakness, either in your own flat or the flats above, because the main timber joists are still securely fixed where they should be on the main wall.
Dry lining the wall shouldn't harm it in any way as long as you don't try to drill and fix the stud work to close to the cracking parts. The brickwork might still be a bit loose if hit in the horizontal plane. Because they're currently under compression they should hold themselves in place well enough for the job they need to do. Keep the stud work at least a brick and a bit length away from the edges of the crack so you don't loosen the bricks at the weakest non-bonded points.
Also make sure the chimney pot on the roof is tightly sealed against the weather so you don't create a space for dampness to get a hold behind the old fireplace. If this can't be made for a sure seal, then leave a small vent over the old fire opening to allow air to pass through and keep the chimney flue dry.
These suggestions only apply if you know for sure that the crack isn't getting any worse, and that you're sure you know that in the time you've been living in the house, you've never seen a crack appearing through the plaster anywhere on the that wall. If you have any doubt in these facts, then call a structural engineer and have them examine it for you and advise if any further remedial work need be done before you start to hide it again.
Good luck with it all, and have a very happy new year.
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On Sun, 02 Jan 2005 00:45:34 +0000, BigWallop wrote:

Thanks for the advice. I have only been in the house a short time, so I think it will be best to contact a structural engineer.
Many thanks.
Chris
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