Floor spec check

[poynton phil]

Got a 27mq porcelain floor to do, and was wondering if this spec sounds ok.

18Mmm chipboard, onto joists, with waterfed ufh

Chipboard screwed to joists at 300mm centers, all joints supported and screwed

Chipboard overboared with 6mm hardie backer, glued and screwed at 150mm centers

Durell uncoupling mat, and tiles stuck down with keraquick spf

Any advice will be appreciated, Thanks.