The sub frame has been taken out and various thicknesses of “Celotex” insulation glued in. Yeah, glue it in. You don’t want all that board squeaking as you drive along. I used “Gripfill”. Alot of Gripfill over the whole build. Buying it by the box would’ve worked out cheaper. The floor was already boarded so I left it down. Two reasons for not lifting it and putting a timber sub-frame below were that 1, headroom would be lessened and 2, I was going to use 6mm thick carpet tiles with a 12mm underlay anyway. Hope that’ll be enough.
