Best way to raise my kitchen floor??

[leeroysw20]

Hi peeps...I've just built an extension on the back of my kitchen where a conservatory once stood. The floor is exactly 40mm lower in this part than in my kitchen and as we want to tile the floor I want to raise it to the same level throughout. Had the idea of insulation board then ply ontop then tiles but I've read this isn't a good idea due to movement. Besides screed is there an easier option??? I did want to add insulation board so I thought maybe 20 insulation board then 18mm plywood ontop possibly?? Then tiles straight ontop of that. Could that work?

you can lay a floating floor as you describe.

Is the floor new?

Does it have a DPM?

www.kingspan.com/gb/en-gb/products/insulation/kingspan-insight/articles-and-advice/why-and-how-to-construct-a-floating-floor

p.s.

before making a decision, seek out a recommended local tiler from people you know and trust (not by looking at advertising websites, especially if they are disguised as Checked or Rated listings) and ask her advice before giving her the job.

There are cement-based boards that may be more suitable for tiling on than ply. I have known them used in Australia for many years but they are getting market penetration here. They are hard, rigid and waterproof.

Hardibacker is a popular brand, mostly used for bathroom walls that will be tiled.