Insulate & Levelling floors

My ground floor is insulated except for the kitchen which I did first and tiled. Unfortunately laying nice level floor tiles is not one of my talents. Walls no problem, but the kitchen floor is quite wavy- up to 10mm height difference in places.

I'm finally planning to insulate the kitchen floor the same as the rest of the ground floor: rigid insulation on the floor with 11mm OSB on top followed by laminate. (This works perfectly well in the rest of the house).

Question is: should I put levelling compound over the tiles before putting down the insulation etc, or will the 3 layers of insulation, OSB & laminate (totalling around 50mm) effectively mitigate my crappy workmanship of a few years ago? I can live with a bit of bounce in the floors.

If yes to levelling compound, which one is the very easiest & most idiot proof to use?

Thanks.

macnug

Sorry i have no answer to your question but you put down osb on top of insulation? I didnt know this was a viable way to raise a floor. I have a floor that needs to be insulated and raised about 160mm. How long have you got this down?

https://www.boards.ie/discussion/comment/120066102#Comment_120066102

It's down almost 3 years. 40mm insulation + OSB + laminate flooring. No issues so far. It doesn't have any give when you're walking on it, but you'd know by the feel of it the laminate isn't laid on concrete. And no way was I going to be digging out the concrete floor, laying the insulation & pouring concrete on top of it as that would have been massive hassle & outlay for marginal additional benefit.

I'd say you'd be grand with insulation + OSB. I've a part of my garage floor which I'll be raising by a similar amount using that method (I'd be insulating the floor that way anyway). Biggest benefits are cost & speed: you can have a new surface ready for flooring within a day rather than waiting 6-8 weeks for concrete to cure properly.

It's probably a million miles away from best practice, but perfect is the enemy of good— an OK-ish job (and sometimes even a bad one in fairness)done today is usually far better than a perfect job not done for decades or at all (eg National Children's Hospital, multiple legal challenges to grants of planning permission, Metro North etc etc etc). Perfection is anyway unachievable in real life.

macnug

You have me intrigued now. Is the floor bouncy? Its for a sitting room that used to be a garage at the side of the house. Id be looking at 125mm insulation though, is thicker insulation less rigid, more bouncy? Probably 22mm osb and 12mm laminate.

I have the height i could probably get a slab in but im basically either doing it myself or getting a trade in which will take months probably.

Not bouncy. It may in fairness be my imagination, but laminate on timber upstairs doesn't feel as hard to me as laminate on concrete. The laminate downstairs feels like the laminate upstairs rather than the old laminate which was downstairs before insulation.

Rigid floor insulation has concrete poured on top of it all the time, so I don't think it's an issue with 125mm. I used 9mm downstairs & will again, so 22mm OSB will more than do the job of safely spreading the load.

I'd guess between OSB & insulation you'd be looking at around €40 per square metre to raise the floor that way. Concrete alone would probably work out significantly cheaper if you got it delivered + pumped and levelled it yourself. I'd guess about the same price (or a bit more) to get someone else to do it for you.

For me personally, speed and maximising thickness of insulation would be the main factors. If the sitting room is decorated, add in the cost & inconvenience of decorating again after the concrete is down. That may or may not be fine for you to get a concrete floor.

macnug

Yea sure I have laminate upstairs and it's fine. I know what you mean about the hardness but that wouldn't be a problem for me. Concrete would be cheaper but difficult to do on my own. Have done smaller area, mixing myself and was fine but a large area like that would be hard work, even getting a load in would need a couple of hands. The room itself is getting totally redone but the access is decorated so mess is the reason i dont want to Concrete it.

Thanks for that. It's my next project and if I end up going with I'll let you know how it goes. Cheers.