18mm ply will probably give you a more stable surface than 9mm over floorboards. Most of the time you do want to avoid increasing floor depth too much.
Most of the time you do want to avoid increasing floor depth too much.
Why is this? I would have thought the more floor, the more solid underfoot it'd feel. I remember my father in law having karndean in his kitchen and it always felt like a school dining hall with concrete underneath.
OK, thanks, that sounds like something - is that to keep height low? Or for a better end result (possibly both) and what kind of mat are you talking?
Something like this: https://www.tilemasteradhesives.co.uk/anti-fracture-mat/tilemaster-anti-fracture-mat ?
And does this sound achievable for an idiot?