Adhesive or self levelling compound

[Bitpipe]

Getting quotes to tile the basement - it's quite a large area, just over 100m2, divided into a hall and four rooms.

The slab was hand finished with a boom, not power floated. As such it has a few ridges but is fairly flat.

We're using reasonably large tiles, 800mm square and are getting different opinions from different tilers on the best prep.

One has suggested grinding down any high spots and using adhesive to make up the levels (but warns that we may be in iffy territory if there is more than 12mm adhesive) wants £10/sqm just for prep.

Other has proposed using a self levelling compound which is about £600 in labour and about same again in materials.

Thoughts?

[Roger440]

When i tiled my garage, i had the same problem, it was not that flat.

The guy doing it said he would use a clip system that meant it sort of followed the floor in as much as it could. I was unconvinced, but now its done, you would never know. The only time i can see its not truly flat is the gap between the bottom of the door and the floor when its open.

Pic of it here being fitted.

 

 

[Nickfromwales]

I've seen that clip system used a few times. It basically squeezes the top and the bottom of the tile together so you don't get any 'kickers' ( corner or edge of one tile not completely flush with the next and much worse at corners where 4 tiles meet / intersect ). 

You usually fit these at the corners and use quite a sloppy mix. It's also quite a task to do with rapid set, but again it's easier if you do this for a living

i personally would go with just running a carborundum block over the spikes, to knock them flat, and then levelling and laying with adhesive as you go. Self levelling can be a double edged sword, as I find if I'm not laying it, it just makes the high points higher therefore only part filling the valleys ( or holes as we call them ). 

I can't speak for your tiler but I'd definitely not go down the self level route if the tolerance is +\- 6-8mm. Any idea what the tolerance is?

[Bitpipe]

6 minutes ago, Nickfromwales said:

I can't speak for your tiler but I'd definitely not go down the self level route if the tolerance is +\- 6-8mm. Any idea what the tolerance is?

It's about that, there are some obvious ridges that can be ground off but it looses less than 10mm over 10m.

As it's concrete and not screed, would something more heavy duty be required?

Edited May 24, 2016 by Bitpipe

[Nickfromwales]

Get on your hands and knees and run a 3 foot long piece of 3x2 along the floor. You'll soon see the 'spikes' ( aggregate stood up in the surface of the concrete) and you just chip then off with a hammer if the brick won't do it.

A days prep in there will save you £'s on self leveller and the labour of it being laid, but be ready for the bill for the extra adhesive as you'll likely use over double the rated amount ( coverage vs M2 vs thickness of bed ) when levelling and laying with adhesive.