Advise On How to Raise Kitchen Floor

[oioi727]

I would like to raise the floor between my kitchen and hallway. The kitchen floor is 22mm lower, and currently has tiles on the floor. The hallway has laminate flooring down.

The new laminate is 8mm.
Kitchen floor is already pretty much level.
edge of existing laminate has a little play in it, e.g. i can lit it up by a few mm if needed.

Thus far I have come up with the following possible options:

1) put down a sheet of dpm, buy 18mm t&g chipboard and put laminate straight on top.

2) buy 12mm osb3 (down side its not t&g), buy 5mm of insulation and put laminate on top

3) but 15mm celotex boards and put laminate on top.

I like the idea of using t&g as i think it will create a stronger base for the laminate to sit on, what do you think?

Any advise that would be great

 

[endecotp]

It is possible to get 18mm T&G OSB3, though it's not as easy to find as chipboard.
Laminate straight onto celotex is not recommended; you need something solid between (e.g. 18mm of chipboard/OSB/ply).
A more solid insulation board such as marmox could probably work though.

 

[Doggit]

If there's a 22mm difference between the kitchen floor, and the top of the laminate in the hallway, and the new laminate is 8mm, then you need to bring the kitchen up by 14mm less the height of the underlay, so assuming a 3mm underlay is used, then you're down to 11mm.

Now you don't need a DPM in the kitchen, so you're going to use either 9mm ply, and have a 1 or 2mm drop into the kitchen, or 12mm ply, and have a 1mm drop into the hallway. But the problem you're going to get, is that the ply will bounce, so you'd need to use a few tubes of Gripfil set maybe 300mm apart to hold the boards in place.

Another alternative, is to use self levelling compound in the kitchen to bring the floor level up to the same as the hallway is underneath the laminate. If you decide on that route, then we can discuss it further.

 

[oioi727]

Thanks for the reply. I plan on using 12mm osb3 sheets, Gripfill is a good call, will buy some tubes of that. Kitchen in 5 meters by 6 meters and I plan to leave the existing units in place and finish the laminate just under the kick boards, they will need to be trimmed to to size.

Just to confirm the order of laying, osb3 with gripfill (leave to dry) followed by 3mm insulation and then laminate on top, is that correct?

 

[Doggit]

Yes, just make sure you put enough gripfill down to stop any bouncing,or you'll get fed up with it. The OSB may want to bend, and 9mm ply might be better. You'll have a door strip, and that will cover a few mill drop.

Edit: and in using the gripfil, you may find the 9mm comes up to the necessary height.

 

[endecotp]

I seem to recall that the recommendation is to allow OSB at least 48 hours to aclimatise in its final location before fitting.

 

[oioi727]

Thank you both for the useful information. I will order the materials and post some pics and update once complete.