How many fixing points for installing plasterboard?

[emmab1986]

Could you please advise me what the difference is between 1/3 and all fastener installations for plasterboard

[MitchellMc]

Hi @emmab1986,

The difference is in the number of fixings you use to hold the plasterboard in place.

All fastener installation means you put in every fixing point shown in the manufacturer’s fixing pattern – every stud or joist gets a screw or nail at the specified spacing.

1/3 fastener installation refers to the process of installing only about one-third of the fixings, typically because you’re also using plasterboard stud adhesive. The reduced number of screws just holds the sheet until the adhesive sets, so you don’t need the full fixing pattern. 

Please let me know if you have any questions.

Mitchell

[emmab1986]

Hi Mitchell,

Thanks for your clarificiation.

would you advise me if these photos show 1/3 or all fastener method?

[MitchellMc]

That looks like a bit of a combination @emmab1986. I've attached the guide for CSR Gyprock below. If it was 1/3, there should be dabs of glue every 230mm along the joists, and those in your image look too far apart for that. We can also see the mechanical fixings. There appears to be slightly more fixings than what would be used with 1/3, but not enough for all fasteners.

What I can say is that even if it might not strictly comply with either method, with the amount of glue and fixings used, I'm surprised it's dropped and failed like that.

Mitchell

[emmab1986]

Hi @MitchellMc

Thanks for your detailed response. 

What do you refer to for this one, " I'm surprised it's dropped and failed like that"?  The house is from 2008-09

cheers

[MitchellMc]

From your photos, it appears that the sheet has detached from the joist as there is a gap between them @emmab1986. The sheet should be hard up against the joist. It also appears there are sections where the fixings have pulled through the sheet and the glue has let go entirely.

Mitchell

[Nailbag]

Hi @emmab1986 

This is definitely a result of not enough glue. As @MitchellMc mentioned this is supposed to be applied every 200mm or so and the sheets screwed. The glue once set is actually whats securing the sheets to the truss joist not the screws/nails. Without glue the fasteners can't hold the weight of the ceiling sheets. This is something I had to rectify a few months back myself for a customer in their garage. I needed to apply glue and then use Acro-props to press the sheets hard up and drive in additional screws.

Nailbag

[emmab1986]

Thanks @MitchellMc 

We also find it strange, as the garage conditions are generally good. A slight sagging along the edge of the plasterboard ceiling was observed after a severe storm event. Could this have been caused by the storm?

[emmab1986]

@Nailbag Thanks. According to the Gyprock Red Book (2008), two methods are allowed:

• Fasteners at one-third spacing

• Fasteners at full spacing without the use of adhesive

I assumed supplementary adhesive was used to enhance support, which might explain why the garage ceiling appeared to be in very good condition—until after a severe storm event.

Could the storm have caused the observed issue?

Are you working for Bunnings or for what company? How many years of warranty for your work?

[Nailbag]

Hi @emmab1986 

It's hard to say what triggered the drop in the ceiling other than if it was significantly more noticeable after the storm, then that would be the obvious cause. Though, due to the lack of correct fastening in the first place, it's highly likely that over time the sheer weight alone might have simply resulted in a gradual drop which started this conversation by @MitchellMc . This was basically the scenario with my customers garage ceiling dropping.

These days, I'm self-employed doing property maintenance and small scale improvements either directly or via a few property management agencies. I also do a lot of work preparing properties for sale for a real estate agent mate of mine. All of which I'm slowly scaling back heading towards retirement before the body falls apart more than it already has. 

Nailbag