Ceiling Crack

Jolly Roger · 23 Oct 2007

We live in a terraced town house about 4 metres wide. On the top floor there is a mild crack that runs from front to back of the house pretty much exactly along the centreline of the house. I reckon the house has heaved and settled a little over the years, so cracking the plaster board which now rubs up and down on itself. This means that the crack eventually reappears after painting. When I last redecorated I drilled a 10mm hole at interval along the crack and filled them with Gripfill in an attempt to stabilise the crack and bond the two sides together, but, a year on, the crack is back!

Any ideas on a more lasting solution? I suppose I could cut a strip out right across the ceiling then re-fill, but it's drastic stuff and I would welcome some advice before do so.

Richard C · 23 Oct 2007

A crack in ceiling plasterboard usually occurs where the boards join &, in many cases, is due to failure of the original scrim tape; unfortunately, the crack will always reappear unless you reinforce the join.

The only real cure (but even that’s not guaranteed) is to apply reinforcing tape along the length of the join & re-skim that section of the ceiling. You don’t have to skim the whole ceiling but it needs to extend at least 300mm either side of the tape & blend in to avoid it being noticeable. It’s a simple enough job if you know what your doing but good results may be difficult to achieve if your inexperienced.

roughcaster · 24 Oct 2007

I agree with what Richard says.But instead of using reinforcing tape,I would PVA, and bed on jute scrim.It would mean a bit more work,but it is far stronger.I would also go along the whole length of the crack first with 1.5 inch screws to tighten up any play in the sheets.Once it has been screwed and scrimmed,it would then be plastered.Again, this way might be difficult without knowledge of the job,but maybe someone could help you.

Roughcaster.

Richard C · 24 Oct 2007

roughcaster said:
I agree with what Richard says.But instead of using reinforcing tape,I would PVA, and bed on jute scrim.It would mean a bit more work,but it is far stronger.I would also go along the whole length of the crack first with 1.5 inch screws to tighten up any play in the sheets.Once it has been screwed and scrimmed,it would then be plastered.Again, this way might be difficult without knowledge of the job,but maybe someone could help you.

Roughcaster.

Oops, I forgot about the screws! Only thing I would say about using jute scrim for a repair is that it's rather thicker than reinforcing tape & so may be more difficult to 'loose' without re-skimming the whole cieling.

roughcaster · 24 Oct 2007

I agree with that Richard, about the jute scrim.It is thicker and stronger,and because of that as I said, there is more work involved in it's use.I would skim the whole ceiling if it was me.It would take away any patched up look,especially if it's in the middle of the ceiling.I wouldn't cut a strip out across the middle of the ceiling and re-fill, as Jolly Roger suggested.It would be great if he knew a plasterer friend that lived local who could help him out.

Roughcaster.

joe-90 · 24 Oct 2007

There is no way that jute scrim is as strong or as smooth as the fibreglass stuff. It's obsolete.

Jolly Roger · 24 Oct 2007

Many thanks for the responses. I simply hadn't thought of screwing the boards up to the joists to stabilise them and can try this with relatively little hassle / making good.
If I tape over the crack and then skim it what would you recommend and how best would I prepare the surface? The surrounding emulsion is not likely to be a very good key for regular finish coat plaster, I would have thought. My plastering skills aren't too bad, though I prefer walls to ceilings!

Richard C · 24 Oct 2007

Additional screws will firm the join up but, unfortunately, will not prevent the crack re-appearing; you really need to tape over it as well. For the plaster, Multifinish should be fine; apply a couple of coats of PVA well past the whole area you’re going to plaster & skim while the second is still tacky. Apply a thin skim over the tape first, working it well into the weave & then apply a second coat so you loose the tape & blend this out into the surrounding area around 300mm each side of the tape. Avoid hard lines either side & you will have to work it quiet hard at the edges as it goes off to get a smooth transition but don’t overdo it with the water or the edges will go flaky.

I’ve successfully repaired cracks like this many times without skimming the whole ceiling, especially if the rest of it is OK. Get it right & you will never notice the additional plaster thickness unless told where to look or you really know what to look for. You may have to do a little local filling afterwards but his should be minimal.

Jolly Roger · 24 Oct 2007

Thanks for the further info, Richard C.
You've clearly mastered the technique and I shall give it a try.
Your detailed reply is much appreciated

roughcaster · 25 Oct 2007

Joe 90,
In my van,I have rolls of jute scrim that I get from my local Builder Centre or from Keyline.Obsolete? Shows you how much you know about it.If it came to a choice between your flimsy fibre tape and tough jute scrim, to do a proper permanent repair to a cracked plasterboard or lath and plaster ceiling/wall,I know what I would use,but it needs more than a thin coat of plaster over it. Go on-line and have a look for yourself,it's readily available.It even comes in 100 metre rolls,not 90, like your fibre tape.More of it and stronger, that's jute scrim.They even use it to reinforce ornamental plaster cornices,ceiling-roses etc.and I use it nearly every day.

Roughcaster.

Nige F · 29 Oct 2007

Top floor

Attic above ceiling in question

go up and stick a section of plasterboard over crack with a slurry of multi-finish

I had a Reliant car once ..it was a one -off prototype , they used jute instead of fibreglass

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Ceiling Crack

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