On 26/10/2020 15:41, Tricky Dicky wrote:
On Monday, 26 October 2020 at 14:21:25 UTC, Dave Plowman (News) wrote:
As part of a re-furb in the cloakroom - new lighting and different
plumbing, I'll have to replace the plasterboard ceiling. Approximately
1.4 x 1.2 meters. Joists along the major axis.

About half way along those, the ceiling changes to a slope - part of the
original roof design. So the joint in the pb at the bend at right angles
to the joists. And the old was cracked there - despite not being that old.

What was a sloping roof above is now a roof terrace, and IIRC the joists
for that not connected to this ceiling ones.

What would be the best way to avoid the new cracking? Suppose I could fit
noggins to support the ends. I don't intend having it skimmed, as that
would require trades brought in. (The old was skimmed but cracked anyway.)

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*Women like silent men; they think they're listening.

Dave Plowman London SW
To e-mail, change noise into sound.
Noggins will certainly help. As you do not intend to skim, presumably you are going to use drywall filler on all the joints in that case joint tape will prevent cracking. Apply a thin coat of filler either side of the joint press the joint tape into the filler with scraper then overfill the joint and tape. Allow to set then apply final coat of filler feathering it out for at least 150mm each side of the joint.

Richard


+1
Paper tape and plasterboard joint filler

I've been using this on some ceilings over-boarded with plasterboard and
then (paper) taped
https://tinyurl.com/yym7re4t

Note the powder takes a lot more water than you first think, mix well
and leave for a few minutes before deciding that the mix is correct. It
appers that ready mix jointing compound in a tub ALWAYS requires extra
water and thoroughly re-mixing to knock out the air in order to get the
best results.

Probably going to the extreme with specialised tape.
https://www.youtube.com/watch?v=65Id0fuTCj0

The Vancover Carpenters Youtube drywall "mudding" (covering joins)
videos are quite good. There are a lot of them.

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