hardwood parquet flooring over concrete

[mulls]

Hi everyone,
I have found many threads on laying hardwood floors but none which address my specific question so I hope you won't mind me asking for some advice.

Here's my situation:
- I have a concrete floor which has been levelled with a self levelling compound.
- Even though its a self levelling product, the floor is still not perfectly level!
- I have 35mm to play with until I reach the level of floors in adjacent rooms.
- I have purchased pre-sealed parquet flooring which is 8mm thick and comes in "foot squares" for easy laying.
- I have never laid a wooden floor like this before!

I would like to purchase and lay marmox insulation board (or similar) for sound proofing and insulation properties. This board comes in varying thicknesses (6mm, 10mm,12.5mm,20mm). I also understand that the floor should be completely flat before laying the parquet.

I was thinking of laying the marmox (probably the 6mm version as thats all the space I will have), then 18mm chipboard to ensure a flat rigid surface. If this seems OK, I could lay the marmox using tile adhesive but then am not sure how (and if) I should fix the chipboard down. Should I screw it through the marmox into the concrete? Should I lay the chipboard first and then marmox on top of that? Should I scrap the chipboard idea and just lay thick marmox - the risk here being that the boards are smaller and I might not get a cpmpletely flat surface.

Any advise/suggestions very welcome.

Thanks.

 

[mulls]

Hi again.
From my searching through other posts, it seems that chipboard is not a great idea when using adhesive to fix the tiles so ply would be what I use. Same question though if anyone has any ideas. If the marmox ends up being on top of the ply then I assume the adhesive will be OK with that?

Also, the parquet tiles I have are not tongue&groove - just straight edged. Does anyone have tips to ensure a flat finish once they are layed. I have read about using a roller but am not sure how big or heavy it needs to be or whether there is a particular technique that produces good results.

Thanks.

 

[WoodYouLike]

How unlevel is your concrete floor now? and more importantly: how well has the leveling compound bonded to the concrete? That is your weakest link.

Indeed, stay away from chipboard - you can hardly glue anything to it, nor nail onto it.
If I were you there are two options you have: glue down small sheets of plywood of the desired height and sand it to level it out before installing your parquet floor, or even better: glue down Industrial grade Oak mosaic (read this for more info on this "Dutch" method: Design Parquet: engineering one of the most stable solid floors). The leveling sanding round will be much easier with this and creates both a very level subfloor and an insulation layer.

 

[mulls]

Thanks for your feedback, woodyoulike. Very much appreciated.

My concrete floor is uneven to the tune of 2 or 3 mm in one particular area - there is sort of a "lump" where I poured too much self levelling which didn't flow too well and didn't realise . The rest of the floor seems OK. I primed the original concrete so I hope the bond between concrete and self levelling is OK. It seems fine at the moment.

If I understand your suggestion, I should just lay plywood and forget about the Marmox? If I may clarify, you are suggesting I use the "small sheets" to accommodate the uneven floor and then sand it all flat? Sorry, I didn't originally describe how uneven my floor is. As it isn't actually too bad, I was thinking I should use large strong sheets to provide rigidity and leave me with a large(ish) area of flat material I can lay my hardwood onto. Would this be an acceptable approach.

Thanks very much.

 

[WoodYouLike]

The larger your sheets, the more risk of flex you will have = breaking the adhesive bond between ply and parquet floor in the end.

You have to try to reduce the "lump" is possible (chisel?) and then glue down small plywood sheets (10mm thick at least).

Hope this helps

 

[mulls]

I see - thanks for that. I reckon I could grind it down well enough with an angle grinder so I will give that a go.

Can you recommend a suitable flexible adhesive I could use to prevent any remaining flex in the ply breaking the adhesion?

...and your views on marmox?

Thanks again for your excellent advice.

 

[WoodYouLike]

To be honest, don't know marmox. What I just read about it makes me think in your situation it is OTT and might create flex too.

Mapei P990 is a good adhesive, but for parquet (wood blocks) we normally use F.Ball B91. You can read about the differences here

 

[mulls]

Thanks WYL. Your advice is, as ever, much appreciated.