how much movement can a flexible adhesive take?

[DrGonzo]

how much movement can a flexible adhesive take?

 

[Softus]

It doesn't really take up movement; it absorbs any minute flexing of the substrate and the tiles and as your walk across them.

You should aim to have no movement at all in the substrate.

 

[DrGonzo]

but a tiny amount of say a floorboard under the plywood is fine?

 

[Softus]

No - I would say that you'd be leaving scope for problems. Lift the plywood and screw down all loose floorboards.

 

[Trazor]

The word flexible applied to an adhesive is a misnomer, as though its elastic, which it is not.
It really dries to a non brittle state, which means it will not crack easily,and allows expansion/contraction to occur, and tiny amounts of movement.
You want your substrate as solid as possible......