gyprocking around windows and butt joints

Hi folks, been building a couple of extra rooms in our house and have got to the dry walling stage. I have ordered 2 sheets for each wall - one will be the bottom sheet and the other the top. Pretty simple right! well, the bottom sheets all go around the walls while the top sheets will all be, you guessed it, at the top. two of my walls have big glass windows and wide reveals. I have cut the bottom sheet for these and now need to do the top sheet for each. How much of a gap, if any, should i leave between the edges of the sheets when the second is put in place?Attachment 530035

I cut this first sheet while it sat against the window frame. Don't think i will be able to do the same for the top sheet. so will cut the window shape out while lying on the floor. this will leave a 27cm strip and two fat ends to manoeuvre into place. any tricks to doing this?

Put small pieces of 10mm plasterboard on the floor under each bottom sheet. This is often ignored but they're not supposed to sit on the floor, despite this being the standard practice on the few home renovation shows I've seen. Butt the horizontal edges of the top and bottom sheets together. Allow 10mm gap around the window reveals, assuming you're going to install window architraves. Make sure your screws don't go through stud adhesive. Screw into each stud around the edges of each board and in the recesses where applicable. Cut some 100 x 100mm or bigger pieces of plasterboard and screw through them into the studs in the middle of the boards to pull them up tight to the studs, making sure you have at least 25mm penetration into the studs, then remove this scrap and fill the holes when the stud adhesive has cured. There are special screws for these middle bits but for a small job ordinary plasterboard screws will do. If you're using a drill driver, get yourself one of these to make it easier to sink screws to the correct depth on the face of the plasterboard.
Just a moment...

EDIT: Just looked at your picture. Looks like your reveals are proud of the plasterboard and the plasterboard is butted up to the reveal, so ignore my comment about the 10mm gap around the reveal.

thanks for that, 419. for the life of me, i could not remember what my dad taught me to do for butt joints. that said, the last house we did together was 40 years ago and he had my brother and i up on planks holding the roof sheets up while he nailed them in. i think i was 10 at the time. Haven't seen one of those driver bits before. Always just guestimated the right amount and then hand tighten to finish. i'll have a look for one tonight.

and yes, the reveals are 140mm on a 110mm thick wall. Didn't want to cut them back and make a dog's breakfast so went big. I cut around the window with the board up against it so the fit is pretty good. we will use quad around the reveals to keep it pretty.

Make sure you have an assistant to help lift that top sheet as it is highly likely to crack with the window cut out if you try and lift it by yourself.

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