How to cover seams in plywood ceiling before painting?

[cbeck1530]

I'm wanting to paint the bedroom ceiling, which is made of plywood panels where the seams are quite obvious. I've heard that it will be difficult to make it smooth so the seams cannot be seen once it's been painted. Should I get a professional in to do it, or could I use caulk, tape, drywall mud, or something else? If you can direct me to specific products that would be fantastic. 

Thank you!

[MitchellMc]

Welcome to the Bunnings Workshop community @cbeck1530. It's brilliant to have you join us, and many thanks for your question about sealing gaps in a ceiling.

I'd suggest a product like Selleys 480g White 3-in-1 Silicone Sealant would be suitable for the job. It's a flexible, paintable sealant that can be caulked into the gap. It doesn't shrink or crack and provides a smooth, paintable surface. I'd recommend you squeeze it into the gap, and as you go, take a scraper and run over the area, smoothing it flush with the timber on either side. I've created a rendering below for you to illustrate. Make sure to scrap off any excess sealant that is on the face of the boards.

Please let me know if you have any questions.

Mitchell
 

[cbeck1530]

Thanks very much! We will give this a go and hopefully we can do it properly and it doesn't leave lines after painting. Much appreciated.

[cbeck1530]

Hi again, 

After looking at it more closely, we've noticed that in some areas the plywood panels do not line up with each other well as there is some bowing of the wood between where the nails are. In these misaligned sections there is no supporting beam behind the panels to nail it into, as I had previously assumed. Is there any product such as a low profile tape which we could use to smooth the surface before painting over the top? Should I try to glue the edges of the panels together? 

Again, your advice is much appreciated.

[Akanksha]

Hi @cbeck1530,

Thanks for your question. Mitchell is currently away on his weekly break but our resident D.I.Y. expert @EricL should be able to assist you when he's back online later today. In the meantime, let me tag some of our helpful members @Peggers, @diy_hausdesigns and @Dave-1 to see if they have any thoughts.

Akanksha

[Dave-1]

Good morning @cbeck1530 

I actually like the style of your roof as is I also think it may be hard to smooth the joins because of the nature of the product. 

Can you gain access to the roof space? I f you can then you could mount some battens beside or between the rafters so you can then nail out the warps/ripples you have.

I dont know of any tape that I could suggest, nothing i know has that level of strength or id be willing to plaster over it. 

Would you be interested in covering the joins with a timber strip? something along these lines 2.4m moulding tasmanian oak ? Then you could paint without having to fill/sand so much?

Dave

[EricL]

Hello @cbeck1530 

My apologies for the late reply. I'm in agreement with @Dave-1's idea of mounting battens otherwise it will be impossible to get rid of the warps and ripples in the plywood. Interior designers often use timber moulding to create a coffered effect. This also has the benefit of hiding any joints in the ceiling panel. I've drawn up a sample sketch below to give you an idea of how it can be installed.

In regards to using a low-profile tape, it's possible to use plasterboard jointing tape but it would stick out as the multipurpose joint compound would be too thick. Plus, it will not hide the ripples in the plywood.

Because timber is a natural product you can expect that it will move and flex as the seasons change. If you are not able to screw the plywood to a batten, I can only recommend sanding it down as best you can and using Selleys 480g White 3-in-1 Silicone Sealant to cover the gap.

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

Eric

[cbeck1530]

Thanks everyone for your advice. We've decided not to paint them as we can't get access to the roof space and the seams are in different places compared to other upstairs rooms, so the battens would be inconsistent. However we did decide to add battens to our hallway and I'm hoping to sand and stain the ceilings when we can. Thanks for your help!