I am about to lay 5mx5m of 22mm (6mm wear layer) engineered oak flooring on top of the original t&g wooden floor of a 70s bungalow with a 3.5mm ProVent underlay. I was originally just going to float it at 90degrees to the original floor glueing the tongues and leaving a 7/8mm expansion gap at all ends. However, I came across tongue tite screws that seem similar to secret nailing and was thinking this would perhaps provide a firmer fix to the sub base. Should I use these in preference to glueing and if so, how does the floor expand /contract? This is important as one side of the room has a large expanse of glass (bifold doors) and gets a lot of sun ( SE facing).
