Tiled Concrete Subfloor

Hi,

Sorry for the lengthy post, hoping to get some advice or general thoughts

I've recently moved to an oldish 1960-1970 property and I'm looking to replace the downstairs carpet with an engineered wood floating floor, wanting to save some money l I figured I'd try it myself

The boards are 14mm thick and 2.2m x 0.18m and click together they are to be laid ontop of a 5mm underlay with dpm built in (sort of a gold foil)

However taking up the carpet revealed the entire ground floor had been tiled with thin 3mm plasticy tiles, stuck to a concrete foundation with a black tar/bitumen adhesive
A small amount of the tile has been removed around the edges of each room and in doorways where carpet grippers were nailed in and I assume broke the tiles

These tiles are well stuck down and easily cracked, I've had suggestions that they're potentially asbestos tiles so I'm wary of doing too much with them

So my initial plan (and this is likely stupid to an actual professional) was figuring the tiles were level as there's no obvious cracks or uneveness and to fill in the missing gaps around the room edges with a substitue, I did some tests with cheap stickdown tiles and they fit perfectly in the gaps and bring everything to the same height, I've also cut some underlay and put that down and putting a few trial boards down it feels fine

However reading up on installation I see a lot of emphasis on subfloor flatness which I wanted to check before comitting so got a large 1.8m spirit level and tested it out, both on the tiles and underlay in multiple spots

And I can find a few spots where the spirit reads as level but you can actually push it down at one end as there's a gap underneath or a bump at one end, some rough measuring with gauges shows these gaps from floor to level range from 1mm to slightly above 3mm in the areas I've checked, often moving the level further up or down a foot or two closes the gap

After placing a few test boards down in these spots I can't feel or hear anything when walking on them I'm not sure how much is being offset by the underlay and weight of board but my concern is the dips or bumps have just been hidden under the boards and will only cause issues in the near or not so near future

Would anyone have any thoughts or recommendations? is keeping the tiles feasible, or would it be best getting someone in to remove and dispose of the tiles and adhesive and have them smooth out the bare concrete itself which is something I have zero knowledge of or equipment for

Many thanks

 

Uplift the tiles, give it a screed and job done.

Would need a damp test before any screed goes down to make sure there's no moisture present.

 

Thanks, reading up on similar situations the recommendation generally seems to be take up tiles and do it properly
I was hoping to save some cost / time by re-using what's there but I don't think it's worth the worry it'd cause

I'll find someone to take a look and get some ideas on costing

 

Had someone over earlier this week to take a look they didn't think it looked too bad, recommendation was to remove any loose or broken tiles and seal over the fixed down ones then screed over the top to level everything out

Assuming its cheaper than removing them all, does this sound reasonable?

 

It’s doable but not the right way as the screed is bonded to tiles which could come loose over time.

 

All depends how loose they are but I wouldn't want to take the chance if it was me. Get yourself kitted up, boot the family out and get scraping...bet they'll come up easier than you think

 

Thanks again, I forget the exact terms/product names used but sounded like a layer or two of different products

They were able to pull a few up tiles with little effort and I've since been around the edges this evening and found if you angle it right can cleanly pop them straight up in one piece just by hand which tends to loosen the surrounding tiles too, I suspect you'd end up removing most of them trying to find the well stuck down ones

I will inquire about taking everything up and disposal when I hear back, if adds too much cost I'll spend a saturday and do it myself

 

Just do it yourself, bet you'll have them all up and fly tipped in an hour

 

Oh I don't think it'd take long, its getting rid of them that's the trouble there's nowhere nearby that takes them and transport is a bit limited at present
will have a think