En-suite ceiling - slight bulge of 3mm and to re-plaster

[smallsteve1]

I am refurbishing my en-suite and one job is to get the sparky in to move the ceiling lights to better positions. Generally speaking the ceiling is not in great condition and so I am looking at re-skimming it to tidy it all up
I used a straight edge to check how flat the ceiling is and there is a slight bulge in the middle of approximately 3mm and i'm not sure how to deal with it or whether it is an issue at all? Is there an accepted way to straighten-up the ceiling prior to final skim, or would you just proceed with a standard skim on the basis that you won't be able to notice such a small bump?
For info, many years back re-skimmed a couple of rooms and so i am reasonably competent at tackling the job. TIA

 

[Dereekoo]

If you didn't notice there was a bulge before you used the straight edge it can't be much of an issue?

 

[smallsteve1]

If you didn't notice there was a bulge before you used the straight edge it can't be much of an issue?

Visually perhaps it isn’t, but I am wondering whether you would normally try to straighten this out when skimming, or just disregard it and skim as per normal method!?

 

[Deleted member 292770]

screw it up

 

[johnny2007]

When I redone my ceiling, there were 2 joists 12mm lover than the others, sitting on brickwork not perfectly levelled.
On plasterer's advice I just boarded the lot and he levelled it up perfectly flat.
Plasterboard flexes a lot.

 

[smallsteve1]

screw it up to make sure it’s not popped off the nails or screws and skim it out. 3mm is nothing.
instinctively you should know from the level where to skim thicker.

Yeah I was wondering whether it is an acceptable method to just apply the skim thicker at certain points, Bearing in mind that two coats usually comes to around 5mm only. The other issue being that the thicker lay will go off more slowly than the thinner spread. Never tried it, hence the posting.