Uneven floor

[checkmate]

Hi all,

I am doing laminate in my living room and my living room has one side of room slightly higher than the other side of room. My issue is with laminate that will cause some issues.

The uneven is around 10mm. I had plans to lay hardboard on top of wooden planks(that's already there on top of joists--sorry not sure of exact terms for this) then underlay then laminate.
But where the room is 10mm or so lower isit better to lay hardboard then self leveling compound to bring to level or is there another better way?

 

[bobasd]

what you call planks are maybe T&G floorboards - usuly 5" or 6" wide.
you need to now the cause of the 10mm drop.
sounds like a joist issue .
can you look or get under the floor and examine the joist seats/pockets?

 

[dazlight]

Use 9mm plywood and some feather finish screed if needed.