Plastering Problems

[micko]

Hi guys

I have joined 2 halls together by removing a doorway.
One hallway is 10ml Fibrous plaster about 40 years old and the new hall is 10ml plasterboard to matchthe thickness.I cut a piece of timber and nailed it up as a backing.
Then I nailed up the 10ml plasterboard in a butt join for the new hallway.
I then used fiberglass tape,2 layers of base coat then a finalfinish coat.
It looked great until it developed a hairline crack a week later.
I put another layer of finnish coat on but it cracked again later.
Any ideas guys?

thanks
Micko

[GCP310]

Have you got timber floors in your house??

Any movement in your home will re crack your join.

Could you V join down the two sheets,fill the join with a silicone or no more gaps that is to a degree flexible,then pain over the top. the paint and silicone will allow a bit of movement without the cracking?

Hope I was a help to you

G

[echnidna]

It sounds like the timber backing could be moving and cracking the plaster. If it was mine I would remove the timber and glue a bit of plasterboard behind the join. There is a proper plaster adhesive but liquid nails will do the job.

There used to be an invisible tape for putting over hairline cracks that cover easily with paint. It could be worth trying otherwise go to the big fix.

Sand the edge of each each sheet tapering out from the join for about 50mm so that you end up with a wide v joint about 6-8 mm deep at the join. Then apply your tape in the bottom of the groove and apply the base coat. Let the base coat dry for a couple of days before you apply another coat or the topping.

[micko]

Hi guys,
Yes there is timber flooring and the house is on clay soil (with lots of funnell webs but that is another story).
I agree that there is movement in the house so maybe a flexible join could be in order.
I there such a thing in plastering as a flexible join?
How would paster backing make a difference to a timber backing?
I think a cover strip would be my last resort as I would prefer a continuous hallway to onr wiyh a join.
thanks for the ideas .I welcome any suggestions.
micko

[Oldblock]

Stopping cracking is a git of a bamble. Sooner or later the crack will reappear. Better (in my view) to put in a proper control joint using metal lath. Rondo make this and so do Gyprock.
Check out your local Gyprock supplier for How To pamphlets.

[Caliban]

Originally posted by micko
Hi guys


It looked great until it developed a hairline crack a week later.
I put another layer of finnish coat on but it cracked again later.

thanks
Micko

It's that bloody Finnish coat. You should use good old Aussie stuff in our Climate, that Scandinavian stuff can't handle the heat.
Sorry couldn't resist. Some good advice from other people, the idea of gluing plasterboard behind the join is the best advice IMHO.
Good luck
Jim

[micko]

Actually it was Lafage not gyprock or something like that.It doesn't sound Australian but it's made in Sydney.

Unfortunately it's too late to put plaster behind as I already put a piece of oregan and nailed the edge of the new plasterboard sheet to it.
Maybe I'll scrape a groove and fill with no more gaps to make a flexible joint.
thanks
Micko