My house extension has a low metal roof with foam ceiling. Can 3mm Premium plywood cover the foam?

[Fatcat]

Hi,

Please advise me if I can use 3mm premium plywood for this job? 

Light weight have to bear in mind because the whole roof is supported by cross bars.

Intend to staple the 3mm plywood on to squares of 60 X 60 cm frame created over the whole roof of size 9m X 7m, as shown in the picture.

My concern is, can plywood take the heat from the metal roof?  Will the plywood ceiling be distorted after some time due to the heat in summer? Will the plywood ceiling sag?

Thanks!  Looking forward to hear from you.

[Fatcat]

[BIM_Engineer]

@Fatcat
Welcome to the forum
You might want go back into edit mode and upload images
Generally, the better the image and data the better the response
Consider,
A wide photo, &/or close up,
Photo of an accompanying hand sketch, cross section, notes
LOL, you won't be judged on artistic merit
Cheers

[Fatcat]

Ok,. I had posted another clearer picture. 

Hopefully that will give an idea

Thanks!

[BIM_Engineer]

@Fatcat thanks for the photo
Unfortunately 3mm ply is a bit too thin for nail fixing to a negative grid ceiling detail.
you might want to try  9mm premium Grade plywood

[Fatcat]

Thanks!!!
Please also advise me if the heat from the metal roof so close to the plywood ceiling does any distortion to the plywood after some time.

[BIM_Engineer]

The solar heat on the metal deck roof shouldn't cause the plywood to distort
Though sagging is a problem with thin and less stiff materials spanning greater/purlin distances.(Assumptions, Rafters @900mm , 9mm ply mass 9kg/m2, 22x Sheets 2.88m2 ea)
OT..If the room gets hot it would also be a good idea to place some additional F/G Insulation batts between the Plywood and underside of the roofing ..just a thought

[Fatcat]

Thanks for your great help.  Your advise is noted.

[Jason]

Hi @Fatcat,

Just wanted to extend a very warm welcome to the Workshop community. I'm sure that you will receive lots of helpful advice and inspiration for your projects from our community members. It's great to see on this occasion that you have been assisted by the very capable and experienced @BIM_Engineer. Please feel free to post again anytime you need a hand.

Jason