I have an 18mm chipboard subfloor, over 400 centres which was installed in the 80s. The CB is sound and I'm about to lay 12mm ply over it then coretec herringbone click. The chipboard, I imagine hasn't got much of the wax coating left it looks like at least 2 carpets over it and in one half of the room, T&G oask was nailed to the chipboard (yes really) but since removed. Should I be glueing and screwing the ply to the chipboard or screw only. Also, I've read that the ply doesn't need to be feathered as it is a floating click LVT. TIA
