Just made myself some new wooden garage doors just wanting some advise on what to do wether to gloss or treat it. Would the gloss stick well to the marine ply?

 

i would 2 coat prime and 2 coat gloss mate, what kind of wood are they made from?

 

The frame is 3x2 sawn treated and the outside is 12mm thick marine ply

 

If the doors do not 'touch' the ground the frame will last 15yrs at least. If it is Genuine Marine ply i.e. BS1088 stamped, it only needs sealing to last. It all depends what finish you want. If you want paint, then prime, undercoat and weathershield gloss is the way. If you want wood, then Sadolin Classic will be ideal for the ply, Sadolin extra for the frame.