Having another thought . Instead of securing the torsion ribs to the underside of the top with screws from above or biscuits underneith , I'm thinking glue only and after the glue has set I'm going to brush in fibreglass resin . I'm not talking the cloth JUST the resin. I've used it on MDF in car audio and when the resin dries nothing's moving . It will also create a barrier from humidity so it's a win win . Once the inside is complete I'll screw and glue the 1/2" MDF bottom .
I definitely see why you guys recommend plywood over MDF for the torsion box ribs , as I'm pretty sure seeing as its laminated wood it will resist flexing a lot better than MDF would
I donít always insulate , but when I do .
Ok ,I never insulate