When to worry about cracks?

[RainRainGoAway2020]

I’ve noticed a lot of cracks appear in my house over the past 6 months. DH says nothing to worry about but I am starting to wonder as most haven’t been here before in the 5.5 years we’ve lived in this house.
They are all hairline cracks in ceilings, vertical cracks in the coving around the ceilings etc.
We had a lift conversion 3 tears ago and new windows last year. We redecorates our hall and stairs before Xmas and all of the cracks are already back.

Did they just paint over the cracks? If so, they do reappear. They have to remove/cut out along the area with the crack and fill it back in. Then paint over that.

Are you in a clay area? We had a very wet winter, I wonder if that has had an affect.

What were your original windows? Were they wooden? Is the house old? Sometimes in older houses wooden windows are actually structural and replacing them with UPVC can cause sagging and pressure. Ceiling cracks I wouldn’t worry too much about, the plaster may be starting to fail if it’s old, give the ceilings a press and see if there’s any give or spring.

If cracks widen or grow, or develop in places like window corners if may need to be looked at. You can mark the end points with pencil and monitor growth. The house we have has historic movement and settlement and we have actual large wrinkles in the lounge wall and a floor slab about an inch lower than it should be 😂 (the floor slab will he fixed, the wall not so much)

Go outside and check your external walls. Did you check with a structural engineer about the loft conversion?

Trying to answer all your questions here. Yes we are on clay. We just replaced old upvc windows with new. The decorator said he did Fill the cracks properly - he certainly took long enough over it.
No visible cracks outside. The loft was converted by a specialist company who handle it all from plan to building the sign off.