Subfloor - Thermoplastic tiles, bitumen adhesive - how to level

[Cellophaneskies]

Hi all.

Tale as old as time. 1967 house, concrete floor downstairs has horrible thermoplastic tiles secured with bitumen adhesive or similar. Kitchen has already had these all lifted and covered with limo. Hallways had them removed and it has been tiled which is holding up fine. Living room still has tiles down.

I can sometimes smell the horrible stuff through the carpet and it’s driving me mad. The floor isn’t perfectly flat either - someone has laid some concrete or something where a fireplace used to be. I’ve lived with only loose carpet over these tiles for a while and I never observed any damp. One corner has a slight crack, 6cm or so, and from memory the chunk looks like it’s black all through, presumably this is screed kn top of concrete floor?

Anyway I’d like to level floor and seal the smell in. I read so many different things online. ARDEX NA seems to be the choice for these sort of surfaces, if I remove all tiles, but their site says make sure bitumen is not ‘water softenable’. If it is, they recommend layer of NA, DPC, NA. Online I’ve seen people recommend putting down SBR first..

So my questions..

- how can I tell if I have mechanical dpm? Never seen damp so I assume I do but I don’t know.
- if I do have one, would it hurt adding another painted dpc layer, as ARDEX suggst
- bitumen being water softenable - does this literally mean, it goes soft when water is applied?
- seems weird to me that the solution to water softenable layer, is apply NA anyway, with more on top. Wouldn’t the bottom layer be compromised?
- is sbr needed? ARDEX don’t refer to this
- has anyone done this before, can you offer any insight and advice?

Thanks

 

[dazlight]

It prob won’t have one and even if it did it would be perished now. So yes a Dpm sandwich will sort it out.
Give the floor a scape with a blade scraper 1st.
Then na straight to it.

 

[Cellophaneskies]

It prob won’t have one and even if it did it would be perished now. So yes a Dpm sandwich will sort it out.
Give the floor a scape with a blade scraper 1st.
Then na straight to it.

Don’t you love houses. Thanks for the advice. Probably best to ‘play it safe’, my only worry is it might bring the level up above a door threshold but I’ll see what I can work out.

 

[robinbanks]

Consider taking the tiles up carefully and disposing of them appropriately as it's possible they contain asbestos. Even though the fibres are well encased in the plastic, and thus relatively harmless, I wouldn't scrape them, personally. Instead a heat gun and patience peeling them up

If you want to make sure, you can send a piece of one for analysis to any one of scores of labs around the UK- the UKAS service can help you find one

 

[crazydaze]

Do you plan to lay a floor on top, or just walk on the Screed?

The simplest way to tackle the area is to

Uplift all floorcoverings and tiles
Apply Ardit NA
Apply painted DPC
Apply final coat Ardit NA

Only issues with the above is that the Ardit NA is not a finished floor surface so will wear away if it does not have a floorcovering installed over it.

You can do the same as above using F-Ball products, we would:

Uplift all floorcoverings and tiles
Apply F-Ball 1200 screed
Apply F-Ball F77 painted DPM
Apply final coat F- Bal 1200

But thats because our installers are used to F-Ball products

 

[Cellophaneskies]

Do you plan to lay a floor on top, or just walk on the Screed?

The simplest way to tackle the area is to

Uplift all floorcoverings and tiles
Apply Ardit NA
Apply painted DPC
Apply final coat Ardit NA

Only issues with the above is that the Ardit NA is not a finished floor surface so will wear away if it does not have a floorcovering installed over it.

You can do the same as above using F-Ball products, we would:

Uplift all floorcoverings and tiles
Apply F-Ball 1200 screed
Apply F-Ball F77 painted DPM
Apply final coat F- Bal 1200

But thats because our installers are used to F-Ball products

Hi

It would have covering installed over it. Ideally real wood floor, if not a laminate flooring, final option would be carpet and underlay.

 

[Cellophaneskies]

Consider taking the tiles up carefully and disposing of them appropriately as it's possible they contain asbestos. Even though the fibres are well encased in the plastic, and thus relatively harmless, I wouldn't scrape them, personally. Instead a heat gun and patience peeling them up

If you want to make sure, you can send a piece of one for analysis to any one of scores of labs around the UK- the UKAS service can help you find one

Had them tested and they came back negative, thanks for flagging this

 

[crazydaze]

Hi

It would have covering installed over it. Ideally real wood floor, if not a laminate flooring, final option would be carpet and underlay.

If you have an Engineered wood floor you could glue this to the top of the DPM if the floor is level enough and save the cost of the second Self Levelling Screed area.

If you plan to float the Wood or plan on carpets then you'll need the second Screed Coat. Remember to stick and NOT pin the gripper if you have carpet as pinning the gripper with compromise the DPM!

 

[Cellophaneskies]

If you have an Engineered wood floor you could glue this to the top of the DPM if the floor is level enough and save the cost of the second Self Levelling Screed area.

If you plan to float the Wood or plan on carpets then you'll need the second Screed Coat. Remember to stick and NOT pin the gripper if you have carpet as pinning the gripper with compromise the DPM!

That’s makes perfect sense.. areas of my floor have no tiles or bitumen and I never see any evidence of damp in those areas at all so I’m sceptical that I need DPM layer but I’d rather have it and not need it than have the reverse issue..

 

[crazydaze]

That’s makes perfect sense.. areas of my floor have no tiles or bitumen and I never see any evidence of damp in those areas at all so I’m sceptical that I need DPM layer but I’d rather have it and not need it than have the reverse issue..

You won't be able to tell by looking at the area, you need to test the floor with a protimeter or ideally a Hydrometer Box to be sure.

Obviously going with a screed/dpm/secreed sandwich negates the testing entirely.

 

[dazlight]

You have no signs of damp as your sub floor is breathing.

 

[Cellophaneskies]

You have no signs of damp as your sub floor is breathing.

Even when covered with carpet? In my hallway I have tiles, am I causing issue there with no additional DPM? Ie removed thermoplastic and put down ceramic tiles

 

[dazlight]

Will be ok with carpet as that lets the floor breathe abit.