How level does a floor need to be?

[IJWS15]

Want to put engineered wood down in the dining room. 5m x 4.2m with a 1.6 x 1.4m rectangle missing from one corner.

Fl;oor is solid, probably screed on concrete.

Appears to be less than 3mm variation over a metre where I have been able to look (still some furniture in the room) but there is a crown of around 7-8mm in the centre of the floor.

Don't want to raise all the rest by 7-8mm plus the floor thickness.

Is this within the limits for an engineered floor or do I have to take some of the crown off.

 

[WoodYouLike]

Take some off - as much as possible so you only have a 3mm per meter sloop. You will regret it if you don't - no floorboard can take that much be it solid or engineered

 

[IJWS15]

Looks like a noisy, dusty day with the SDS drill on hammer then.

 

[IJWS15]

Any recommendations for a floor levelling compound for a screed floor some of which has been painted?

e.g. Is Bal Multibase as good as the data sheet implies?

 

[Gteuk]

I tend to use screedmaster 2 latex based level, 3mm is quite a lot per 1m2 unless a good quality underlay is being used, go for a 6mm Poly Ethylene underlay which can absorb (sp) 1 to 1.5mm of undulation.

Ensure you use a D3PVA glue also when laying the floor even if it is a click system.

the uneveness of the floor is also dependent on the size of the board, i.e. a 2.2m board will act as a see-saw on a hump breaking your joints pretty fast.