How to attach wooden flooring to steel bus floor
I want to maximise standing room and am prepared to trade floor insulation depth for extra headroom. I was planning to glue 4mm x 3cm (sorry we're metric over here!) wooden batons to the steel floor about 20cm apart running lengthways up and down bus, in filled with one layer of bubble foil insulation. On top of that I will lay interleaving gymnasium flooring (maple strips 1.8cm thick and 4cm wide) sideways across the width of the bus, so the total depth is about 2.3cm.
Do I need an impermeable layer of plastic sheeting as well?
The question is how to fix the wooden floor to the steel substrate. I was going to use self tapping screws (say 4mm screw and 3.5mm pre drilled hole) and a countersunk hole in the gym floor so the screws go through the maple strip, the baton and into the steel floor. I would then cover the screw with wood filler and varnish.
What have others done?
My Build site is https://schoolbusconversion.net