Repair Holes and Levelling a Concrete Floor

[JJC001]

Hi

I want to prepare my concrete floor for laying down engineer wood planks. The floor must be level to lay the planks.

Currently the floor has some kind of plastic tiles stuck down with a tar like black adhesive. I think these were put down at the time the house was built (late 60s).

While lifting the carpet, this was laid on top of the tiles and the gripper rods (holding down the edges of the carpets, the tiles at the edges of the floor broke and came away.

It is extremely easy to lift the tiles using a wallpaper scraper and this leaves behind the black adhesive with little grooves in it (like when you put up tile adhesive).

Around the edges of the concrete floor near the outside wall about a 2 to 3cm wide and 3cm deep strip of (screed) has broke into a rubble and is very loose. I have cleared away all of the loose bits leaving quite a deep hole in places.

Now onto the questions.

1: With what should I fill the holes in the floor near the outside wall, some kind of conrete or loose small stones and then pour self levelling compound over the top (I read this on the back of the self levelling compound packet but I am not sure if this will work well).

2: Should I lift the remaing floor tiles as they are so easy to remove? I am thinking yes but then some messages in the group seem to state you can lay the compound over the top.

3: Can I put the compound on top of the black adhesive? This seems to be competely secure to the floor (only the tiles can be removed easily).

4: Does anyone know if the B&Q Value self levelling compound is any good. I have also seen a product called Feb Concrete Self levelling filler is this better?

5: It seems like self levelling compounds I have seen are for concrete floors, does this mean that it has to be poured directly onto concrete?

Thanks

John.

[The Natural Philosopher]

My advice FWIW.

lift all tiles and as much of anything that comes away easily as you can.

Treat the whole floor with a dousing of thinned PVS, execpt the really loose stuff. Here use full strength PVA. This will bond all the loose stuff together.

Then use levelling and smoothing compund on everything - don't attempt (unless you have > 2" deep big holes) to use a normal cement screed.

Be aware that self leveling compund isn't self levelling. You need to float it on if you can. you may need tow goes useing a long sitrit level to detntify any hollows and fill them. A uniformly flat surface is more important than a dead level one.

[rrh]

I have to agree with this. Also, I recently used it for the first time on a small and not very uneven floor, expecting an easy job and armed with just one 5kg tub which said it could cover (IIRC) 3 sq m - the area of my room - to a depth of 3mm. Well 3mm was useless. I ended up getting a 25kg bag of the stuff and using almost all of that as well before getting a halfway decent surface to tile on. Perhaps the floor was more uneven than I thought, but it was quite difficult to use.

[JJC001]

Thanks for the advice, what is PVS & PVA? Where can I buy it?

Thanks again

John.

[JJC001]

Thanks for the advice, how many mm would you say the height of the floor increased by during this levelling process, I want to avoid increasing the height too much as it will impact the hearth of the fireplace!

John.

[anthony james]

We spent last weekend levelling 20+ square metres of concrete floor to lay Karndean. We had already removed the laminate floor, the cork tiles underneath that, the glue (with a hot air gun and water for different areas) and patched large holes with a cement mix (not sure what it was but can check - it was a 'just add water' mix in a pot) The floor was then cleaned and pva'd.

Saturday was spent putting down 'Green bag' latex levelling compound. Of course being inexperienced we woke on Sunday to find a strong smell of fish and a floor that was now exceedingly uneven as all our trowel marks were visible. This stuff is not self levelling so the advice elsewhere about how to level will be useful. We then spent 4 hours with 'Feather finish' which we essentially reskimmed the whole floor with get it smooth.

The end result was very smooth but probably no more level than it was when we started though any sharp lumps were much more gradual.

Whatever else you use get some Feather finish as it's intended to go down very thinly and will help make good any areas where you screw up with the latex. I'm not at all sure we gained much by removing all the old glue - i suspect the latex screed would have bonded just as well with the floor as it was.

[rrh]

Very little. It wasn't an issue in this particular room so I didn't measure it, but I would reckon maybe 5mm, certainbly less than 10mm.