leving floor for insulation and screed

[seka1980]

i will soon be putting down 80mm insulation with 80 mm screed on top.
problem is that in some rooms, there are some large dips in the floor.
whats the best thing to use to level these dips so that the insulation sits flat to the floor?
i was wondering if sand was any good?

cheer
jon

 

[hotrod]

Define "large dips". What are you talking about 25mm??250mm??

 

[seka1980]

sorry
they are about 10 - 25 mm deep
and about a meter sqare

 

[seasickstevie]

Best with self-leveler. Use one that can bulk up more than a few mill.