It's 12mm (1.2cm) indeed. I corrected myself in the original post, sorry. What is the acceptable tolerance?
Thanks for the answers. There is no movement... it's like the wood follows a (pretty) uneven base. It stays concave even if I walk away. Or lets...
Hello, I've just gotten new wooden floors, placed yesterday and today by a professional. We knew our floors were not perfectly flat, but the guy...