plasterboarding kitchen ceiling is this right ?

[lilac]

I worked out that to do my ceiling I would need a certain no of 1200 x 900 and 1800 x 900 12.5 mm boards however my Wickes only has 1800 x 900.
So am starting again and will have to cut somewhere. The room is 383 cm x 307 cm but there is an alcove of 47cm x 155 cm to fit round.
The joists start 3 cm from the edge wall and are every @ 40 cm apart so I can't 'start at the corners' as the wickes person suggested
Is it best to fit these across the joists (at right angles) or along the joists ? does it matter as long as secure.
Also on my previous post I was advised to fit them - with one board butting the join on the other like bricks - but this will mean more cutting.
Finally Wickes told me to use plasterboard plugs and screws - is this right ? do you really have to drill 10mm holes in the joists (2") and push in a plastic fitting before screwing in ? what if this splits the wood....can you screw straight into the joists or is this worse ?
The previous owner just used big nails and a big hammer. thanks for your patience !

 

[lilac]

also is there a definite answer - white or brown side up ?

 

[buster52]

get full size from someone like travis perkins or any builders yard that delivers 2400x1200 (8ftx4ft) there cheap enough

 

[Richard C]

Don’t fart around with small boards, get full size 2.4m x 1.2m x 12.5mm boards, it‘s cheaper & they are not as difficult to put up as you might imagine; even on your own! They can be cut very easily by cutting through the white paper face with a Stanley knife, snapping the board & cutting through the backer; or cut with an old rip saw but that makes a lot of mess & won’t do your saw much good. Always fix white side facing outwards/downwards, it’s this side that gets plastered. Don’t know what the Wickes bloke is on about with the plasterboard plugs, use plasterboard screws on every joist spaced at 200mm max; don’t use nails. Fit the boards with the longest side running across the joists with a 2-3mm gap at joins & stagger adjacent boards so the short edge joins are in the centre of a joist & not in line with the next board; don’t worry about the 3cm overhang on the first joist to the wall it won’t matter. The joints must be taped but I suspect you’ll be leaving that to your plasterer.

 

[lilac]

thank you so much - I don't know why wickes sold me plasterboard plastic plugs for wood ? even the packet looks like the plugs go into a wall
Perhaps Wickes could use this forum for training staff ??? thanks again.

 

[lilac]

PS Guess I will have to have them delivered !