[DKAudio]

I got a Kohler Archer bathtub. I was reading through the manual and it says either use construction adhesive under the 4 wood blocks of the tub or use a 2" thick bed of mortar in between the blocks. Which is preferred? The manual says the tub need no additional support other than the 4 blocks but I guess personally I would feel better with a bed of mortar for the tub to squish into. If I use mortar should I use plastic under and on top of it?

Also, my floor (house built in 1954) has diagnal 45° guess is 1X6 or 1X8 boards across the joists, then plywood or real oak wood boards depending on the area of the house. I haven't removed the old cast iron tub yet but from what I can see the tub is directly on the diagnal boards with nothing else. Should I put some plywood under the tub as well to disperse the weight more or will it be fine leaving it alone? If so what type and thickness?

Thanks