Plasterboarding ceiling

[Staffbull]

Can you let me know which way the plastervoards should run, with the trusses or against them (long edge of the board) and which way up, smooth paper side or rough.

I think they should run with the truss timber, and my brother thinks they should run against, i think they should go smoothside down (plaster face) and he thinks rough.

A also think the short ends of the boards will be OK butted together unsupported as the centres are only 360mm.

As you can tell neither of us are plasterers !! and I cant remember which we we put up the rest of the house five years ago !!!

[Guy King]

The message from "Staffbull" contains these words:

Personally, I wouldn't.

[Stuart]

I would think you will get greater support by running the boards across the trusses but cutting the boards so they end halfway on a truss .

Doing it the other way,along the trusses means you only have support along the edges ..and you WILL,imho,need to support the ends with cross pieces betwen the trusses ..

The boards should be marked which side is to be decorated . I've not considered one side to be smoot and the other rough .The boards I used recently had a dark and a light side .

Stuart

[visionset]

Yeah and the light side (grey) is smooth and the dark side (brown) is rougher. The former is of course the side you decorate whatever that is with.

[Tom]

Yep, just drylined a room with Gypsum board, it says to expose the lighter side as you can decorate or plaster directly onto it. Some Knauf boards i used recently had no markings on them though.

HTH

Tom

[The Natural Philosopher]

50/50. Across the joists, and smooth side down.

Not really. At least they should be taped up before skimming

[Stuart]

I've just looked at a piece of board .Knauf I think .There isn't really a lot in it as far as smoothness is concerened .

Stuart

[<me9]

The cut edges should be supported on a joist. the other edges will be ok at

400mm spacing, but at larger spacings (particularly with 9mm board) they should be (but often aren't) supported by nailing to noggins.

[Andrew Gabriel]

You plaster or decorate the ivory side. You may find references saying decorate ivory side or plaster grey side, but this was for plasterboard > 20 years ago, and doesn't apply anymore. In practice, it makes little difference for plastering.

This can work if all your ceiling joists are level, otherwise you end up with steps. I might not do it with 9mm plasterboard though. Leave a 1/4" gap between unsupported edges, and start the plastering by forcing bonding coat plaster through the gap and right through to the back, with an excess overflowing onto the board tops. This will bond the board edges together so they can't move relative to each other. Apply scrim tape (nylon course netting) to the joins before you put the finish coat on.

If you are not doing the plastering yourself, ask the plasterer if he wants the 1/4" gap at floating edges -- some do, some don't.

[Staffbull]

Found a guide ! across the joists, I'll ask the plasterer if he wants a gap, coming tomorrow for a looksee and price. (he was half anyone else for the rendering so should be OK)

[John Rumm]

Across the joists IMHO

Most boards I have seen have a light and a dark face, where plastering and/or decoration are supposed to be carried out on the light face.

No, much better cut to end on a joist. Otherwise you are far more likely to get cracking at the joints.

The other thing to do is stagger the boards to add more bracing and rigidity to the joists:

If your joists run thus:

# # # # # # # # # # # j j j j j j j j j j j # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # # #

Board like that: _______________________________ | | | | | | | | | | | | |___________|___________|_____| | | | | | | | | | | | | |_____|___________|___________|

[Staffbull]