"Chris Walton" wrote in message
news
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):


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.