Nails coming out from underneath ceiling and overload on cornice

[Sugar]

Hi guys, 

I suddenly started noticing screws underneath the ceiling around my house. Actually, I started noticing them when I was painting interior walls. I have attached the images and pointed with RED arrow ( not clear but should be good enough to see).

Is this something I need to be really worried about? And what is the reason for them to protrude?

Thank you in advance guys.  I am a little worried about this now. 

My last image shows how there are curves formed on the cornices, which look like because of overloading. I can see them at a few points around my house. 

Is this also something to be worried about and what is the reason for this?

Thanks guys

[MitchellMc]

Hi @Sugar, 

I don't believe there is anything to be concerned about with the nails unless there is some type of underlying issue going on. They are popped nails and just about every house gets them. Taking a walk around mine I count dozens of them, many pushing a small amount of the plaster off as well. The fluctuations in outside humidity, especially in Summer, contribute to your timber frames and gyprock ceilings expanding and contracting at different rates. As the nails are fixed to the timber but pass through the plaster they can back themselves out.

To fix the issue you can drive a plaster screw on either side of the nail into the timber above. Make sure you drive the screw in far enough that the head is just beneath the surface of the plaster. This will draw the plaster back up against the timber. Once this is done you can tap the nail back into place. Finish up by applying a coat of Diy Multi-purp Comp Less Mess 2.25kg, sand back the surface so it is flush and re-paint. 

If you are particularly concerned about this you could employ the services of a builder to inspect the roof for you.

With the wavy cornice, I am not sure what might have caused that. Are there popped nails in that vicinity as well? I don't believe it has anything to do with over-loading of the ceiling. I would imagine there are most-likely joists above those sags contributing to the issues. I also don't believe it is sagging as I would expect that over a larger continuous area. It appears more like the ceiling isn't perfectly flat and the cornice has been fixed in place originally like that.

Let me mention @Brad, @ProjectPete and @Walzz  to see if they would like to add to the conversation.

Please let me know if you needed further assistance or had questions.

Mitchell