laying hardibacker board without screws?

[tactile]

if a floor is the same level throughout, but is half floorboards and half concrete, is it acceptable to screw 6mm hardibaker to the floorboards but just stick them to the concrete with tile adhesive?

. . . or is adhesive alone not enough?

[Mike]

is there any movement in the floor boards? any movement at all and they'll need overboarding with ply before backer boards. you'd be better using slc to bring the concrete side level with the boards. and you'll have to have a joint where the wood meets the concrete

[tactile]

no there is no flex on the boards, i was thinking about using 2 part floor adhesive direct on the floor because they're that sturdy, but was worried about the movement between the concrete and wood boards over time. But i thought the hardibaker throughout might work?

[tactile]

I really didnt want to put a joint between the 2 sufaces as its in the middle of someones kitchen!

[Mike]

you'll have to put a joint between the 2 substrates. you may be able to put a grout line there and use colour matched silicon in the grout

[whitebeam]

As above coloured silicone to match the grout colour to fill the tile joint.

[tactile]

ok, will let the customer know what i have to do, just to make sure he's ok with that. Is fixing Hardibaker down with tile adhesive alone still viable though? . . . .

[Mike]

i can't see that being a problem but you're better off using slc i.m.o.

[grumpygrouter]

I find hardie isn't exactly flat and the adhesive may well not "pull" the board flat to the floor....I have done exactly what you are wanting to do and I had to drill plug then screw the board to the screed to get it flat!

[jay]

any ufh in the concrete

[garythetiler]

if you are going to stick the boards down prime the backs with sbr bond as it stops the boards from curling off the adhesive