Sealing newly laid concrete subfloor

[dave_104]

Hi
I've got a newly laid concrete subfloor that's pretty well flat and at the right height to follow on with engineered flooring (with 3mm foil underlay) - I won't need to be building it up with latex or anything. The slab is entirely tanked in with 1200g sheeting and therefore unlikely to be sucking in additional moisture from the ground.
It's been laid for several weeks now and I think I should now seal it? But I'm still doing further work so I'll expect to reapply sealing once that work is 100% complete. (I don't mind doing this twice as the adjoining room is completely finished and a lot of dust is transferring to the other room).

Would it be best to do it so soon or should I wait a few more months? and any recommendations of a decent product like something bulky or rubbery which would smoothen out the surface even better? There is a low point (about 2ft square) that I need to fill by around 5mm, should this be filled with concrete or tile adhesive or latex?

Thanks, Dave

 

[23vc]

Why do you need to seal it? Use bagged self levelling mix to level it

 

[dave_104]

Thanks for your reply 23vc. I've done many things but not dealt with a concrete floor before, so quite often I may be overthinking something......
I was really just wondering if it's normal in my situation to put down some form of additional protection, especially for moisture, such that if the membrane gets damaged or salts come out the concrete, or whatever else could potentially leach from the unprotected floor. I don't want somebody in the future saying to me "OMG! you didn't seal that slab before putting down your expensive engineered floor" (this is where I worry too much!).
I wasn't looking to seal from stains (like you'd do with paving slabs), it was more as a liquid DP barrier, possibly using SBR as the sealer. I don't know what's normally used - if anything at all.
It can't be entirely raised by the way by self levelling as it's at the correct level already - apart from the low area so I guess SL is ok there.

 

[23vc]

Yeah, no need to seal it, just patch as necessary and feather out