Subfloor preparation for EvoCore LVT flooring

[Husker]

Hi, I've recently purchased LVT flooring (EvoCore Premium). The floor it's going to be installed on had vinyl which I've removed leaving behind what appears to be a layer of adhesive on a concrete floor (please see attached photos). When removing the old vinyl some of the adhesive beneath broke apart leaving patches where you can see the concrete floor beneath. My questions are therefore:

1. Am I correct in saying this is some type of adhesive? Should I remove all of it before installing the new flooring?
2. If I need to remove all this adhesive, can the LVT flooring be installed directly on top of the concrete or do I need to have some moister barrier installed first? Do you mind posting some examples?

This is the flooring I went with: EvoCore Premium - West Coast Grey Oak

It has 1.5mm foam cushioned underlay already pre-fitted. Not sure if this affects the decision behind having to add a moister barrier or not but thought I would mention it.

Any help would be much appreciated!

Thanks.

 

[Mark Brown]

You my friend and kind of correct. Your floor is covered in adhesive but in addition to that is also a layer of floor patch, thats what is flaking off. It would be in your best interest to remove it simply for the fact that as you use your new floor it is likely to become uncoupled from the concrete and make crunching and annoying sounds for the rest of time. It is a bit of a pain, but that is the best course of action.

If in fact the rest of it is securely bonded to the floor, you could always float more floor patch over it and repair the chipped out parts. That is not the end of the world either, I just worry looking at the images that what is there is not bonded the best to that dusty concrete underneath. Moisture barrier on concrete is never a bad idea in my opinion, it is a cheap insurance policy for your health more than your floor in this case, but less damp is good damp.

 

[Husker]

Hi Mark, thanks for the prompt response. That's a good point regarding the uncoupling over time. I've started the removal using a hammer + chisel - it's slow-going but I'm getting there. Would an oscillating multi-tool be worth investing in to help speed this process up? I have my eye on this one: https://www.argos.co.uk/product/7967397.

 

[Mark Brown]

They aren't typically beefy enough to really help.....
Will it work... yea, but not the best.

For that patch your best bet would be either a 5 inch scraper, a demo hammer with a flat head on it or day labour

If you find it is REALLY bonded, just skim over it with more patch. I cant say what is because I am not there but you are, you will know

Depending on what kind of tile/adhesive/misery a floor presents I use a 5 inch razor scraper, 4 inch putty knife, my electric tile stripper (oscillating tool on steroids, kinda) floor removal is a bitch, hands down... but it is worth it every time.

 

[C.J.]

I’d go at it with a putty knife or a 5 in 1. If it’s stuck enough to not come up with one of those trying to get under it, it’s stuck enough for a floating floor.

 

[Husker]

@Mark Brown / @C.J. Thanks for the info, appreciate the help. I've made some progress and I've come to realize most of the patch has a very strong bond to the concrete (about 90% of the floor is like this). I'm therefore inclined to skim over with more patch as you've suggested, Mark. To do this I presume it would be best to skim over the entire floor with a thin layer of screed ensuring all is level? My first thought was to cover the areas which came apart only but it probably makes sense to chisel away the pieces which have come loose until I get to where the bond is very strong, repeat this for all areas where the concrete is exposed, then apply a layer of levelling screed across the entire floor to ensure it's all level. Would that make sense?

 

[Mark Brown]

I usually do the whole floor, but that is because I find it to be faster, I am fast. Plus, you can even out anything else that might not be correct.

You are definitely on the right path now. If that stuff is bonded there is about... let me think, uh, no reason at all to try and remove it. Make is smooth, make it flat and have fun!