hi all

im currently stuck on my layout with roofs for my engine sheds

one span is 4ft and another 2 at 2ft

I have tried MDF with plastic sheeting glued on top and eventually it bowed and always keeps bowing

I built within the shed a plastic sub frame to support the roof buts still suffer with the same issue

I was looking into trying balsa wood but thought I would see if anyone might have better ideas

Chris