Overboarding

[CortinaV8]

Never really liked the idea of overboarding but I think needs must in this case.

What size boards would you use for this job? and would you use 1200x2400 or smaller boards?

If i was confident in the condition of the plaster on the ceiling I probably wouldnt be bothering to overboard, but the ceiling has been wallpapered at some stage which suggests to me the plaster probably isnt in the best of condition underneath it.

[Richard C]

The paper would have to come off before re-skimming anyway so overboading is probably a better option for you if you don’t know the condition of the original boards underneath unless you want to take them down; not difficult but can be rather messy. Overboarding is not usually a problem & you won't be able to tell once they are up there & skimmed. 2400 x 1200 boards are always preferable unless it's a small room as it reduces the number of joints across the joists & hence the potential for cracks. Establish the joist layout & screw through both boards into the joists. Board longest edge across the joists & try to establish where the original board joints are (cracks usually a give away) so you can overlap & not coincide with the original board joints.

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Richard C

[CortinaV8]

Should have said its lathe & plaster, hence why i've no real desire to take it down, I removed the ceiling in my hall stairs and landing which created shed loads of dust.

Any ideas on board thickness?

[tommyl18]

use 9mm plasterboards they are the lightest and thinnest

[PrenticeBoyofDerry]

Lathe and plaster super messy,horrible stuff
Go with the largest size plasterboard you can handle, I tend to use 2400x1200x12.5mm.
As it reduces the amount of joints and depending on size of room the waste.
Identify your joist prior to fitting, the easiest way is if you can get above the ceiling i.e under the floor above. I aet a small drill bit a drill down at the both side of the joist and both ends of the room.
This will identify the centres in between the two holes either side of joist, then I put screw in at the centre of one end of room and screw in the at the other side, leaving them proud so I can wrap a chalk line around them and snap a line from one end to the other of the joist, repeat this on all joist.
Makes live easier for measuring boards and finding centres, plus a chalk mark on the wall to identify the joist there too.
If you can't get from above, using joist detectors can help but you need a good one.
The cracks can give it away and the distance between joist can vary but the standards are 400mm or about 16 inch.
Be aware that there could be cables and or pipes in the ceiling void.
when fixing a run of boards stagger the joints.
http://www.zurich.co.uk/NR/rdonlyres/5EE95D52-D851-4D52-A8BF-4E5D5F270C8D/0/500045004BG900204WebOpt.pdf
Other than that RC's explained things well.

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Dum Spiro Spero

[Richard C]

CortinaV8 wrote:

Should have said its lathe & plaster, hence why i've no real desire to take it down,

In that case I wouldn’t either.

CortinaV8 wrote:

Any ideas on board thickness?

As PBD, I prefer to use 12.5mm on ceilings rather than 9.5mm; heavier, yes, but a lot more robust & will suffer slight undulations in the lath as well.

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Richard C