Straight crack in the ceiling (Ed.)

[JohnD]

I suppose they'd prop it first, to get the middle about the same height as the edges, but this would not make it flat. It would have two or three dips or humps, due to the permanent set,

 

[Ivor Windybottom]

I feel like I've had a headful of drugs after reading this thread.

If you're actually bothered about your ceiling then perhaps try to stick to the topic instead of pasting in pointless ChatGPT ******.

Is the ceiling bent? If not there's nothing to worry about. Presumably someone who knew what they were doing designed it in the first place, it hasn't been altered so there's probably nothing to worry about.

Ceiling cracks are normal. Especially where the joists run perpendicular, as the joint between boards is mostly floating in air. Plus it was probably nailed up rather than screwed, nails tend to drop over the decades.

Just screw it to the joists. If you really want belt and braces then fit some noggins along the joint and screw to that.

It's very unlikely the re-roof is relevant. Unless the ceiling is actually bent, in which case you've got far bigger issues than a cracked ceiling.

 

[Ivor Windybottom]

Be aware that overboarding a ceiling will add significant weight to it. Check the joist dimensions and span, if it's already near the limit then perhaps don't. Plus yours has the added load of the wall above it. There's a limit somewhere, a layer of plasterboard isn't going to make it come crashing down but it may make it sag.