New LVP over multiple subfloors

[Adam Sharp]

Hi BP Community,

I need some advice. I own a condo (1/10 units) on the ground floor tucked into the hillside in Seattle. I’d like to redo the flooring in the combined foyer (tile on slab) and living room (carpet on 1” something on plywood) ; rip it out and put down LVP. I’ve been looking at the HD brand LifeProof with the underlayment attached.

So here are my questions:

1. Any idea what that 1” something is? It’s grey and looks like fuzzy dried concrete when I poked a drill hole through it. It is hard like concrete on top tho.

2. Can I pull out the carpet and lay self leveling compound on top of that 1” something? My guess is yes? Do I need to refinish whatever that is if the existing floor flatness is adequate?

3. It is going to be a challenge moving everything out of my 500sf condo to do this big job so I was thinking of doing the foyer first as it will be simple. Level the existing slab and lay the LVP - Q: how difficult will it be to match the level of the transition btw the slab and the 1” something? Is this a recipe for disaster or is there a straightforward way to attack this?

4. Do I need to put anything under the LVP to protect /insulate it from the slab? Seattle is cold and wet. Manufacturer recommends nothing but does anyone think I can add a little extra protection, insulation, and soften imperfections in the subfloor?

Thanks in advance for your help. I’ve done a ton of research and know I can do this solo I can just see some hiccups that could potentially be costly if I don’t do my due diligence up front.

Thanks!!

[Michael Haas]

When installing direct-to slab I always

1. Seal the concrete with paint on sealer, 2-3 coats

2. Lay down 6 mil vapor barrier

Concrete will almost never be perfectly dry so those extra layers of protection will keep your LV dry. That won’t help with cushioning or heat retention though- I’d recommend a waterproof underpayment like pergo gold for that. If you go that route you can skip the 6 mil, although I’d still seal the concrete while it’s exposed and you have the option. 

Best option for heat retention and leveling is always a plywood subfloor on 2x4s or thinner sleepers- this would make leveling a breeze, but you do sacrifice some ceiling height. 

Let me know if any of that doesn’t make sense, and Good luck!