Overboarding questions

[Poiup]

So... I have decided to attempt overboarding a few of the ceilings in my house.
I will start from the smallest one and see if I can actually manage it and then move to the larger ones if I consider it feasible.

The joists are spaced 40cm and the ceilings are artexed. I don't know if they contain asbestos or not. To be on the safe side, I will use the necessary PPE and try to be as clean as possible.

My questions are: is it best to use 9.5mm boards or 12.5mm?
As far as I understood 12.5 is generally better, however, I am a bit concerned about the added weight, especially for the room on the second floor as the weight would be on the joists that support the roof. After reboarding, the plan is to just tape and jointing rather than plastering.

Ceiling sizes are:
-2.66 x 2.66m: 7.1 sqm (I'd be starting from this one)
-3.70m x 3.20m: 11.7sqm
-3.20m x 4.25m: 13.5 sqm second floor... this is the one that concerns me the most

Am I overthinking this?

 

[Mr Chibs]

Yes, use a decent length screw and crack on.

 

[Poiup]

Yes, use a decent length screw and crack on.

... using 9.5 or 12.5 plasterboards?

 

[Deleted member 292770]

12.5 square edge

 

[RandomGrinch]

As a diy'er (and I may be shot down in flames from the pros! ), when I was overboarding, I chose to use 1800 X 900 tapered edge boards.
Like you, I chose to tape and fill and I was pleased with the results.
Doing the job by myself, I found the 1800 boards were a lot easier to handle; I also used a work platform and extendable props to support the boards (I have tall ceilings!).
...and it may also be worth investing in a pole sander!

 

[Deleted member 292770]

As a diy'er (and I may be shot down in flames from the pros! ), when I was overboarding, I chose to use 1800 X 900 tapered edge boards.
Like you, I chose to tape and fill and I was pleased with the results.
Doing the job by myself, I found the 1800 boards were a lot easier to handle; I also used a work platform and extendable props to support the boards (I have tall ceilings!).
...and it may also be worth investing in a pole sander!

Not at all, I regularly use 6x3’s , Not a problem. I never opt for tapered edge though, unless i’m using thermaline board which only come tapered.

 

[johnny2007]

Have you found where the joists are?
Once you have located them, make sure you get your screws into the joists, not just the old plasterboard.

 

[Poiup]

For the people who might find this in the future. In the end I used a studbuddy to find the joists, made sure to have the right spot by drilling tiny wholes in the ceiling. Marked the whole joists lenght using a chalk line.
There were a couple of places that concerned me as I thought they might have pipes/cables close to the plasterboard so I used a holesaw and very carefully drilled an inspection hole to check the situation.
I used 55mm screws and 95mm plasterboard in most rooms apart from one where I've used 125mm.
The results look much better then I anticipated.