Best way to perminantly fix crack in ceiling

[Geneticsbunny]

Hi all. We have a crack in our ceiling which is where previous owners have plasterboarded but the boards have moved when people bang around upstairs. Can anyone please advise on the best way to DIY repair this?

I am thinking maybe screws with washers to hold the boards in place more securely, remove as much loose stuff as possible in the gap and then use caulk to fill? Would scrim tape help? Do I need the washers or can I just put loads of those black plasterboard screws in?

All suggestions welcome.

Might be useful to note that there will always be a reasonable amount of banging (jumping onto the floor) happening directly above this and this is not something we can change.

Whoops forgot the pic

Bumping for you

calling @PigletJohn

How old is the house?

What are the dimensions of the crack in your pic?

What is above the ceiling?

I have the same issues and after multiple failed attempts I will likely call a plasterer to fix.

We have this issue
with both plasterboard ceilings
and lathe and plaster

The plasterboard ones run the length of the board
The lathe and plaster more localised

We are not getting anyone in as we need repair and so far everyone just wants to overboard. We are listed and not allowed

So I’m waiting on hear on this thread as despite being an Architect ( I should know 🫤) Nothing has worked so far.

I suspect another venture into the creepy roof space is needed

Following

It was built in 1820
Above this room is a bedroom. Between the rooms are two sets of joists, one above the other and running in opposite directions to each other. Very handy for sound insulation purposes.
Not sure if the original lath and plaster ceiling is also under the boarded bit or if that was removed first but there is a 1-2cm deep ridge at the edge of the coving sticking proud of the flat bit of the ceiling so I think the lath and plaster was probably removed.
The crack is probably 5mm at widest point and runs across the full width of the ceiling so around 3m total length.

I thought it might have been. You had better lift a floorboard upstairs to check. L&P is extremely heavy. The cracks do not look typical of ordinary plasterboard joint cracking. It usually shows the joint pattern of the pieces, which are 8ft x 4ft but may have been cut, preferably nowhere near the middle of the room.

If the ceiling is visibly sagging, that is a bad sign.

No visible sagging. It looks pretty flat apart from the crack. Also might be worth me mentioning that the crack is near where a bay window sticks out from the room.

Am I just taking floor boards up to check if it's l&p?

Is the zig zag bit not likely to be the edge of a plaster board? I will try to get some more pics tomorrow.

@StandingSideBySide we have never investigated trying to find someone who can replace a lath and plaster ceiling but we did managed to find a company who left the coving in place and cut the middle section of lath and plaster out, reboarded it and skimmed and it looks good as original. This was a previous house so not the ceiling in question. Not sure if this would be allowed in a listed building but it might be worth asking a conservation officer maybe?

We had this in a house from 18th c. We had to pull down the ceiling and put in sister joists to strengthen and the upstairs floor which wasn’t sagging but was bouncy and creaky- the stage before it starts to sag. This weakness and flexing in the upstairs floor when people walked around up there caused cracks in the ceiling below. Then we insulated and put up new plasterboard. Took advantage of the open ceiling to do some rewiring of the ceiling lights into integrated LED spots as well.

"Am I just taking floor boards up to check if it's l&p?"

Yes.

And anything else that catches your eye. Look at how the ends of the joists are built into the walls, and if there is looseness or cracking.

This house is older than I am used to. There is a good chance the joists will be of ample size (8" x 2" or so) but in some economically built houses, or if there was a loft room above, they can be too small.

Bay windows are sometimes quite badly built.

Thanks very much
unfortunately it’s not allowed

Even in the old kitchen, which only has a third of the lathe and plaster left, the rest is on the floor ( fell down before we bought) we were told we’d have to replace.
If we were grade 2 we may be allowed but we are grade 2star

We can’t even remove old paint, we have to overpaint ( unless if it’s gloss and rotting the wood)

Ive just found old red Tudor paint under black gloss on a hearth and we’ve been told to leave it. So we’ll have patches of red paint on stone. We don’t mind and would prefer it tbh. No one buys a listed building and expects streamlined perfection
but repairing is a mindfield

I had some L&P ceilings remade when they fell down after a burst pipe. An old fellow who specialised in lime did it. I don't know the cost as it was part of an insurance claim.

I expect they charge a daily rate.

I know how to correct and repair a slightly sagging and cracked L&P but it is very labour intensive. I did two small ones over a bathroom and landing. The method is used on restorations.

Might take me a while before I can access the bit under the floor but I will be back when I do.

Would be interested to know your method

We have three areas that need repairing ie are cracked and hence sagging
They aren’t huge at less than half a metre diameter

( we’ll have to get someone in to do the kitchen but we don’t want these smaller areas to get worse before we do. )

I will create a new thread "how to repair a sagging old ceiling" in case anybody else wants to know.

There you are.

How to repair a sagging old ceiling (Lath and Plaster) | Mumsnet

Hmm. The crack is at least partly directly below an external wall, so the bay is only single storey and has a balcony on top. That is going to be an issue if we need to repair the lath and plaster but also might explain the crack. I will definitely need to get under that floor.