floorboards under electric UFH + self level

[kolt]

Hi All,
As usual looking for a word of advice. Plan to refurbish cloakroom. Currently we have old floorboards over joists and lino on top. I am planning to remove lino, put 5-6mm UFH insulation with electric UFH and then close it with latex self levelling. ( the plan is amtico on top).
So the question is, do I have to replace boards with sheet material (chipboard?) to avoid cracks in screed?
Thanks

 

[crazydaze]

6mm ply the floorboards, electric mat, then bury the mat with at least 10mm of self levelling before laying the Amtico.