Sealing plywood under Aluminium

Im at the stage of putting on the aluminium outer skin on the roof and im wondering if I should seal the plywood underneath first?
If so what with?
Thanks
Andy
If so what with?
Thanks
Andy
or t n ttt for short (tnttt.com)
https://www.tnttt.com/
andy2 wrote:Im at the stage of putting on the aluminium outer skin on the roof and im wondering if I should seal the plywood underneath first?
If so what with?
Thanks
Andy