Level Floor with cardboard or plywood?

fix.my.floors

Hi, looking for a bit of advice... I am getting wooden floors fitted in my 2 bedrooms, second story in the house. I have a steel beam that runs across the 2 rooms so leaves the floor slightly uneven. I was onto the floor provider and they said to level if off by putting cardboard of the same thickens around the beams all over the floor. Would this fix the problem or am I better off getting plywood down to level it? Any help or advice would be great!
Thanks a mill

Lumen

What's the height difference you're trying to fix?

fix.my.floors

Only a few mm, i'd say 3-5

Calahonda52

why not proper floor underlay

fix.my.floors

This is what I'm trying to figure out, would underlay or cardboard work or bounce back up once the floors are down or am I better off going withplywood

Lumen

I've used 4mm woodfibre (Gutex HappyStep) for this sort of problem, it's fairly cheap and a lot like cardboard, just handier to lay out.

s7ryf3925pivug

You can get insulated subfloor panels. Could put them down then use self levelling ccompound on the beams if they are now lower than the panelling. Or a bit of wood there. Underlay on top of all of it then. Nice quiet floors.

I reckon cardboard would go mouldy if you ever spilt fluid on the floor. Mouldy subfloor in your bedroom would be bad.

drunkmonkey

Put water ply down and leveling compound, that's what I done upstairs.

fix.my.floors

Yea I'm a bit iffy about the cardboard in case it got damp... woodfibre is sounding like the best solution! Thanks all

Lumen

The only slight worry I'd have is that the woodfibre is somewhat compressible, as is the wooden floor you have, but the steel beam won't be. So it's possible that when loaded you might still have a mm or two height difference. But that'll be under the underlay, so probably OK.