Best way of levelling concrete hearth with chipboard subfloor?

[SJRSJR]

Hi. I'm about to lay new laminate flooring in the living room. There's a 4mm ridge where the concrete hearth plinth meets the chipboard subfloor and I'm wondering what I should do.

Under a previous laminate floor I packed it with extra underlay (just the basic 2mm white foam type) but there was a slight bounce so I'd like to do it better this time. It's only the long edge, the other two sides are fine.

Would a better quality underlay help, should I try and grind down the edge or is there some sort of screed that can be applied to chipboard? Thanks

 

[SJRSJR]

So now I'm thinking that the best way might be to break up the hearth area and start again with a self levelling compound?

 

[oldbutnotdead]

You've probably done the job by now but just in case....if you can afford to lift floor level by 4mm then use the green fibrous underlay (6mm) in the room & put 2mm on the hearth.
Plan B would be investigate the hearth- if you're lucky it'll be 25mm of concrete on top of earth and rubbish- easy to break out, bit of hardcode and sand, DPM, screed, done. If you're unlucky and it's a full thickness proper job then time for messy grinding (shabby, timeconsuming but cheap trick is anglegrinder, diamond discs and fettle it away CAREFULLY with full face eye protection).

 

[bobasd]

whats wrong with priming the hearth and laying SLC to meet the c/board level?then use whatever underlay across a level floor?

 

[oldbutnotdead]

whats wrong with priming the hearth and laying SLC to meet the c/board level?then use whatever underlay across a level floor?

I think the floor has sunk relative to the hearth- tricky to tell from the pics- if its the other way round then yes SLC on the hearth would def be the easy fix