Ridge on concrete floor

[Don'tInvolveYourself]

Hello. I am soon to lay a bamboo floor on a concrete base. I have a DPM and a 6mm rubber-type underlay.

The problem I have is the wood floor will be covering a 40 year old concrete floor and a 3 month old concrete floor in the extension of the same room. Where the two floors meet they rise up. I thought this was a just a localised 'lip' but after chipping at it and grinding at it it seems that for at least 10cm either side, the concrete slopes up to the meeting point of the 2 concrete floors.

I have dry laid a bit of underlay and some floor over it and there is a significant see-saw effect! I am thinking of laying self-levelling compound to take the edge off of it, although this would be frustrating because the whole of the floor except this 50 cm stretch is flat.

Any suggestions?

Also I want to lay the floor this weekend, if I did lay self-levelling compound, how long till I can lay the wood?

Thanks for your help.

Rich.

 

[mattysupra]

you shouldn't really be laying wood until exstension area is dry. As its bamboo you can bend the rules but would still put a sealed vapour barrier below the underlay on top off subfloor. Sounds like it most easy to raise subfloor with leveling compound but will cost you more money. I would grind the high area down or even chop (being careful of damaging dpm) this section out and re laying fast drying mortua. With both methods you will be o.k to lay at weekend as long as finished repairs min of 24hrs before and lay vapour barrier.

 

[Don'tInvolveYourself]

Thank you for your response, I've had a bit of a go at chopping the ridge out, but it seems to be a bit more of a gradual slope than I thought and, therefore, the area that needs to be removed is quite spread out.

It has occurred to me though that if I don't lay my 6mm underlay over this point then everything appears to fit pretty well.

Are there any disadvantages to cutting a strip out of my underlay and allowing the board to bridge over the bit of the floor that is causing the problem?

 

[mattysupra]

you shouldn't do this. There is a few reasons but main one is that the board will hit floor and make horrible noise when walking around. The underlay stops this happening. Think your best to maybe self level or patch repair the uneven floor. You could maybe get a really thin bit of underlay and put it in this section?? But i never said that ! if you know what i mean. Myself i would try and do job properly to save yourself being disappointed in the long run.

 

[Don'tInvolveYourself]

Thanks for your help again Mattysupra. In order to save me time and money, is there any problem laying the underlay and then laying a second layer but with a gap where the floor rises, this way there will be underlay across the whole floor and it would allow for the ridge in the floor. The underlay is 6mm.

I know it would probably be better to self-level it, but I'm not too sure about doing that myself and so it could get expensive.

Thanks.

 

[mattysupra]

you shouldnt double up underlay as you will create to much movement in floor. If underlay very dence then maybe you could but not recomended. You could try fibre boards first then underlay leaving out on high spot and filling in with something thinner. But like i say this isnt really recomended

 

[Roofer]

I don't think it's too much of a job to grind it level look at this