How do I retro-fit insulation correctly before plasterboard?

[WhiteWoolf]

Hi there, we have a raked ceiling in a small living room. The old plasterboard has failed due to water damage and a bad paint job a few years back. As there is no insulation between the ceiling and tiled roof, we have decided to retrofit insulation and new plasterboard over the top. We have installed the wall track and furring channel 90mm down from the existing ceiling as we wanted to retain as much of the exposed beams as possible. We have Bradford sound break insulation R2.5 which is 88mm thick. I've just realised that tucking the insulation behind the furring channel will create quite a gap between the insulation and new plasterboard. Should we run the insulation the other way between the furring channel and use some strapping to hold in place so the insulation is a tight fit between the plasterboard? What should we fix the strapping to? Thank you

[EricL]

Hello @WhiteWoolf 

Welcome to the Bunnings Workshop community. It's sensational to have you join us, and thanks for sharing your question about your roof insulation.

Looking at your second photo, I believe that installing it vertically would be a better option and will produce less waste. There is currently a gap to the left of the insulating panel which you can fill with another panel by cutting one panel down. If you continue your vertical installation method the cut piece can then be used for the next gap. In regards to the insulation strapping, please allow us to double check with our supplier if there is a method of installation for steel furring channels.

Let me call on our experienced members @Dave-1, @Nailbag, @TedBear and @JoeAzza for their recommendations.

If you have any other questions we can help with, please let us know.

Eric

[Nailbag]

Hi @WhiteWoolf 

I stand to be corrected but I think how you have already installed the batts is fine. The batts will already be doing their job and having a small air gap between the batts and the ceiling plasterboard acts as another insulation barrier.

Nailbag

[MitchellMc]

Hi @WhiteWoolf,

I agree with @Nailbag. There's no issue with having a gap between your insulation and plasterboard. In fact, the air gap will increase the insulating value.

I'd continue as you have been, and you could screw some strapping into the existing plasterboard to help retain the insulation better until you get the new plasterboard on.

Mitchell

[Dave-1]

Morning @WhiteWoolf 

Mmmmm I have not installed insulation as yet Tho what you have described sounds like a resonable thought process.

I would continue as is.

Dave

[WhiteWoolf]

Hi there,

We have now installed the VJ board over the furring channel. I am looking for a fairly seamless finish to the edges and ends.

Firstly, on each long edge of the board, I am considering an aluminium L-angle or flat about 30mm wide to bridge the expansion gap. I believe these can be coated with a product that makes the aluminium paintable based on another post I've read. My question is, is there any reason to go with an L-angle rather than simply using a flat?

Secondly, I am not sure what to do at the junction between the wall and VJ board. I would like a modern look, so preferably not the Cove cornice. Any suggestions, keeping in mind the wall and VJ board may both be slightly imperfect (not completely straight due to cutting by hand, and what wall is straight?!) and I will want to hide this neatly?

Finally, some of the screws did not self-embed in the VJ board, despite purchasing the recommended screws (self-tapping, self-embedding course thread screws). A reminder they are going through the board in to metal furring channels. We used screws and adhesive. Is it safe to remove the screws one at a time, drill out the samehole a bit with a countersinking bit, and re-screw in to the same hole; Will the screws still hold well enough?

Thank you very much

[Dave-1]

Good Evening @WhiteWoolf 

Its looking good  

Removing a screw and then countersinking and redoing the screw should be fine, if you notice that the screw isnt gripping as you would expect then id suggest to go up a size in the screws.

I prefer timber trim to finish edges, mainly as its old school but in your case it may be a pain to drill, countersink and then install the screws through the aluminum trip. Is there a reason you are thinking aluminium over timber? I like L shaped trim whichever way as it gives a clean line to look at on the beam and also the sheet. My sunroom has square trim to frame the old school VJ board and probarly hold it in place truth be told. It still looks modern

Dave

[WhiteWoolf]

Thanks, Dave.

I was thinking aluminium because it would be very thin, maybe 1.3mm, so hopefully almost invisible on the edges once painted. As the beams are so dark and the panels will be white, I was hoping to avoid a 'frame within a frame' look. I was also going to potentially glue the trim rather than screw it on....? I don't think the trim will be providing any support, just a nice clean edge. As for the panel to wall junction, probably a timber moulding of some description, again as minimal as possible.

Cheers,

Kellie

[JacobZ]

Hi @WhiteWoolf,

I've used aluminium flat bar in a similar application on commercial offices. They weren't painted as they were there to match up with other aluminium trims, but they looked good in that application and there's no reason they couldn't have been painted. We glued them on with liquid nails and had no issues at all.

Aluminium angle is also an option that could look quite nice, but it will reduce the ability for expansion and contraction by connecting the ceiling to the wall.

It would be difficult to implement now that the sheets are in place, but a PVC Casing Bead is also an option that would look clean.

You should also consider whether you can just run a bead of No More Gaps along the seam and then paint it. I can't see any seams in your photos that look too wide other than where the sheets meet the ridge beam.

Let me know what you think.

Jacob

[WhiteWoolf]

Thanks, Jacob!

So with the flat bar, should I glue it to the board but allow a small gap (1-2mm) along the beam and fill that with a flexible paintable sealer? We do want it to be fully sealed and allow for movement as you said. I did buy some tear-away bead when we had originally planned to use plasterboard, butI thought the lip might be a bit high as it allows for flushing around the edges.

At the apex I was thinking a piece of flat timber trim to bridge the gap, again with some sealant on the edges. At that height and mostly concealed by the structural beam going across, it will hardly be visible.

My dilemma now is where the board meets the wall. Would you do an aluminium trim and flexible sealant here too, or would you go for a timber moulding? I want a simple modern finish, but have to bridge the expansion gap as well.

Thanks again!