SLC and tile adhesive for use on bitumen (?) floor

[Thomas Moore]

Hi all. First time poster here so thanks in advance for any help you can give and apologies if I've missed the answer to my question when I've been reading through existing posts.

We've just started refurbing a 1950s ex-council house. We have removed a series of thin, 9" square tiles, which I now believe to be vinyl asbestos tiles, which I understand are common in houses of this type and age.

The tiles came up very easily and with no dust, leaving behind a fairly flat, reasonably uniform black substrate (see photos). This is solid and barely tacky but we're not sure yet how thick the black layer is.

After reviewing lots of advice on these forums (very useful), it seems to me that we probably have a concrete subfloor to which bitumen has been applied to fix the old tiles. A couple of the tile companies I've spoken to have advised that the bitumen is also most likely acting as the DPM. So, first question: does it sound like we're on the right lines so far in working out what we're dealing with?

The floor is generally solid and in decent condition with no break-up, although there is a section in the kitchen / diner where a wall has been removed, leaving a concrete 'finger' sticking out into the floor (approx. 8ft x 9"). The floor slopes by about 2" over 2ft where the two rooms were at slightly different levels before being knocked together and is a little uneven elsewhere, although there are no major dips, bumps or cracks.

I would like to avoid scraping up all the bitumen, especially if it's acting as the DPM but mainly because we're looking at a floor area of about 35sqm.

Ideally, I'd like to level the entire kitchen / diner floor with a self-levelling compound then lay ceramic / stone / porcelain tiles. My question is, what is the best way to prep the existing floor first?

It has been suggested that we just clean the floor of dust / loose material, leave the bitumen layer as it is and then prime it by rollering on ECO PrimGrip, followed by either FlexiLevel or Rapid Level 30 SLC then just tile using a normal adhesive. Does this sound like the best strategy or can anyone advise of a better way to tackle the job?

Thanks in advance,
Tom

 

[Old Mod]

Hi and welcome to the forum Tom.

For me if you're going to use Tilemaster SLC then I'd prime with a Tilemaster Primeplus slurry coat.
Mix 1 part Primeplus with 1 part water and 30% by weight tile adhesive.
Mix well and paint on and leave to dry.
Have u used SLC before?
If not then I'd probably suggest staying away from the Rapid Level 30.

 

[Simon benn Leeds]

Plus 1 on the above, exactly what response I would of given.

In terms of slc's Tilemaster levelflex is the only one I'll use, PERIOD!...

 

[Thomas Moore]

Hi and welcome to the forum Tom.

For me if you're going to use Tilemaster SLC then I'd prime with a Tilemaster Primeplus slurry coat.
Mix 1 part Primeplus with 1 part water and 30% by weight tile adhesive.
Mix well and paint on and leave to dry.
Have u used SLC before?
If not then I'd probably suggest staying away from the Rapid Level 30.

Thanks, guys; I really appreciate the advice and the quick replies!

Just so I'm clear before I go ahead, does the following sound about right:

1. Clean down the existing bitumen surface so it's free of dust, dirt etc. (will thorough mopping be enough or should a degreaser be used? The floor has been exposed whilst light building work has been going on and it's fairly dirty)
2. Apply direct to the existing bitumen surface a Primeplus slurry coat made up of 1 part Primeplus to 1 part water and 30% (by weight) of something like Standard Setaflex adhesive
3. Apply Levelflex SLC across the entire floor area (around 20sqm in the largest room) in a single pour
4. Fix tiles using Setaflex adhesive

It turns out that the downstairs shower room has a similar subfloor so would the same approach be OK for the (potentially) damp conditions in there too?

Thanks again for all your help.

- Tom

 

[Old Mod]

Yeah that's fine Tom.
Out of interest, have u ever tackled a floor like this with SLC?

 

[Thomas Moore]

This one is a first for me and I realise it's possibly a fairly ambitious project.

I'm keen to gather as much good advice as possible, so any guidance is very welcome.

 

[Simon benn Leeds]

Just used the pro rapid 30 this morning for the first time WOW indeed... Ideal for me as laying some limestone so drying colour perfect, and really does what it says.

 

[Dave]

This one is a first for me and I realise it's possibly a fairly ambitious project.

I'm keen to gather as much good advice as possible, so any guidance is very welcome.

Using a straight edge , 2 mtr is good .. Check,how flat the floor is , looking for low areas or humps ... Fill in low areas first if required and then a few mm over the floor to create a nice and flat tiling area.