Floor prep

[ajc]

Quick question for a general consensus please:
I'm tiling a floor soon that is 18mm tongue and groove floorboards, overlaid with 18mm floorboards!!! God only knows why this is the case. The 2 layers of boards are not perpendicular, but the joins are staggered so they are not directly above/beneath each other.
It seems absolutely rock solid (as you'd expect!) but what would people do here? Top layer is highly varnished?
Cheers

 

[White Room]

How many m2 are we talking about here...and are they nailed or screwed.

 

[J Sid]

take off top 18mm layer....
fix 6mm Hardie board as per fixing instructions and lay tiles to this.
should end up about the same night as the 18mm boards which you removed.
assuming the floor is bounce free.

 

[ajc]

it's 5m x 2.1m. Top layer is nailed, not sure about bottom layer.
Getting top layer up may be a real nightmare as stud walls are built ontop of it!

 

[White Room]

The floor plate of the stud wall should be either screwed or nailed into the joists, you would need to cut the overlay floor boards flush with the wall, as Julian hardie glued and screwed but I would keep the boards tight where the overlay floor boards had been cut.
Avoids any possible movement from the stud work.

 

[Time's Ran Out]

Overlay the hardie onto the 2nd layer of floorboards and get a stepladder into the room.

 

[PaulSmith]

I'd remove the top boards and overlay with 6mm HB.

 

[Aston]

i'd also remove the top layer of boards, then you can see the condition and whats securing the bottom layer.
if they are secure and screwed down, you can then do as suggested in the above recommendations regarding 6mm hardie, glued and screwed ensuring perimeter expansion gaps etc etc