Uneven concrete floor

[123hotchef]

Yes.

Thankfully no issues with that.

if it was mine i would screed over the exsisting after sealing the gaps with silicon. it would give the best finish, hold your bog and pestall in also,

 

[123hotchef]

looking at the pics its 3-5mm drop from the concrete to the wood,

 

[brightspark]

this does wood and concrete and is flexible ARDEX FA 20 Fibre Reinforced Smoothing Compound for Timber Floors

 

[123hotchef]

this does wood and concrete and is flexible ARDEX FA 20 Fibre Reinforced Smoothing Compound for Timber Floors

so is the Ball https://www.f-ball.com/en/product/stopgap-300-hd-heavy-duty-underlayment/

been using it for years