Flatness requirements for bamboo laminate flooring

laminate-floorunderlayment

I'm installing Lumber Liquidators' Morningstar XD bamboo laminate flooring in my basement. According to their tech support, they have the following flatness requirements for the underlayment:

(1) no more than 1/8" over 6', and (2) no more than 3/16" over 10'.

A contractor friend thought that sounded excessively stringent. And to meet those requirements I'd need to smooth out the existing concrete floor, so I want to be sure.

Are those tolerances overkill?

Best Answer

It's really hard to provide objective advice. There are many factors, and the shape of the irregularities is critical.

  • Is it a gentle curve or a hard angle?
  • Does it curve in several directions?
  • Is there more than one such issue?
  • Do you have multiple underlayment options, whereby an upgrade could help mitigate the concerns?

It would take a booklet to lay it all out. I'd stick with mfr specs + maybe 25%.