Repairing cracks in ceiling

I guess this question as been asked loads of times!

So, in 2016 we had an extension, single storey. After a few years hairline cracks appeared where the plasterboard joints are.

Almost 5 years later now, I used one of those triangular scrapers and scraped out the cracks, deep and wide with chamfered edges. I then filled the grooves with Tupret interior filler. It was fine for about a month, then until about a week after painting, hairline cracks appeared again.

They are hard to see unless you get very close to them, which I was when I were going to paint a second coat.

It appears that the cracks have formed where the Tupret meets one side of the original plaster.

In other rooms of the house, I've never had any luck with sorting out cracks, so I wasn't too surprised to see this. But is there ever a way of resolving hairline ceiling cracks?

Thanks.

 

when you raked the cracks out were the joins scrim taped underneath the plaster?

 

They were, not only did I see it at the time of the job, I slightly exposed some of the webbing when opening up the joints.

To be honest, over the past few years the cracks appeared, it was a minor annoyance that I was in no rush to rectify. Only attempted to do it now as giving the room a refresh/paint.

Otherwise the plastering job is fine, they did the walls of the extension too and did a superb job.

 

the reason you can see them now is it’s colder and everything shrinks in the cold.
if they’re barely noticeable i’d give it 2 generous coats of dulux silk , which should cover it.
failing that I suspect a retape and skim is the only option .

 

From the scraping out I've done again, it does look like some kind of error in how I did my repair and a combination of what you've said. So we have a problem of something we have shrinking after it goes deep in a crack....

 

Upon closer inspection, it appears it may be something to do with the rate in which the paint dried, being on different substrates, bare filler and previously painted surface. I'll do it again, but prime with Zinsser 123 before repainting.