Subfloor tolerance

[bernadette]

Hello,
New build downstairs is open plan, subfloor laid in two sections,  so half of whole of downstairs is 3mm higher than the other half (which has caused issues with flooring)  builders are saying this is within tolerance?  Does anyone have any advice, we thought tolerance would be a gradient not a sudden difference?
 

[New Home Expert]

£mm would be within most peoples idea of tolerance. Even if it is a step at the join it could easily be feathered out using latex levelling compound before the floor finish is laid.