P'boarding a ceiling - noggins?

[mailbin]

I need to P'board a ceiling (5.5m x 2.9m, with joists at 400 centres) but there aren't any noggins down the long sides because it used to be lath+plaster. I've found conflicting advice about whether or not noggins are needed down the long outside edges and also about whether noggins are needed to support board end joints. Page 338 of the "site book" at

says that 12.5mm board is OK to 450 centres but that noggins are always required around the perimeter, but looking elsewhere it seems that noggins are often skipped. I suspect I've answered my own question by typing this (noggins down the sides but not at joints) but it would be useful to hear what others do.

[Tricky Dicky]

I have owned three houses and none have had noggins either between joists o r round the perimeter. The site book gives you the ideal situation which th ey have to to cover themselves but nobody does it. It's a bit like the inst ructions on paint tins regarding preparation before painting anyone slavish ly following the instruction to the letter would never make a profit. It's a cop out for the manufacturers when things go wrong who can simply say " A h! Did you follow that instruction? No! Sorry can't help"

Richard

[Iggy]

replying to mailbin, Iggy wrote: Add the noggins. Or, add full length timbers. Either is common practice today, it's much better and stronger. Yes, even today it's skipped and plaster-boarders "float" the ceiling edges as a lazy shortcut, since they don't care about fire sealing or blocking and only pursue a pretty package that's patently defective and inferior methodology.

[tabbypurr]

You can do it either way.

NT

[John Rumm]

I would say you want support at the edges of the room, but don't need it at every short joint. (especially if you are using scrim and skim after)

[tabbypurr]

Without support you'll never keep edge cracking at bay. Ditto elsewhere if the gaps are large. But you can be cheap/quick and do it anyway.

NT

[Andrew]

Since expansion and contraction of the entire ceiling is going to result in edge cracking, I don't how perimeter noggins will help.

If you are concerned about fire-stopping the perimeter then fit gypsum coving all round. Sorted.

[tabbypurr]

Without support you also add flexing up/down of the PB, which makes matters much worse.

NT