Basement Slab Issues – mitigation options or repour?
I am currently having a home built and the basement slab has just been poured. The slab has multiple issues, both errors and general poor quality work. I’m looking for opinions on how serious the various issues are, whether mitigation options exist, and whether I should push for the entire slab to be torn up and replaced.
The construction – 2″ XPS 25psi foam board, polyethylene vapor barrier, 3.5-4 inch concrete. Planning for finished flooring over the slab – LVP, carpet, possibly engineered hardwood.
First issue – the poly is 4 mil, not 6 mil as specified (and code minimum…). My concern here is deterioration over time – haven’t found great information, but some suggests polyethylene loses about 1 micrometer per year. At this rate, 4 mil increases permeability past 0.1 (max recommended it seems?) in 25 years. 6 mil would have 75 years to reach that point. We are expecting to stay in this house for ~50 years. We’re not planning to install the finished flooring for at least a year, giving the slab time to dry. Can we then install some sort of vapor barrier above the slab? Liquid applied – epoxy, paint, sealer? Or poly under the flooring material?
Second – the floor is not flat. Noticeable variation across the whole slab, as well as fairly significant variation across small distances. Main concern here is how LVP will perform – thinking we’d have visible bumps/valleys, as well as noise from flexing at low spots. Mitigation options – grinding or self-leveling filler? Complexity of these options?
The slab was supposed to have fiber reinforcement. None exists. Also suspect concrete mix was a lot of water – based on the amount of uncontrolled cracks and unevenness of the slab. Slab was poured in high 80F, maybe low 90F temps, with similar temperatures the following days. No sprinkler, flooding, or any other type of water added. No burlap or poly over it. Based on everything else, I highly suspect there were no curing additives included in the mix.
Existing cracks can be filled with polyurethane, but I’m somewhat concerned about additional cracks developing after finished flooring is installed. How likely is this, if I’m waiting a year before installing finished floors?
Multiple pipe penetrations are completely cracked through the slab around the entire pipe, so it’s easy to wiggle those pipes.
Power screeding work seems to be poor quality – a lot of areas have concentric arcs, both visual and actual ridges. Multiple areas near pipe penetrations and walls have very significant excess concrete pushed up into ridges.
At the moment, I’m considering that the following would mitigate the issues in a reasonable way:
Grind floor flat
Chase existing cracks with grinding wheel and fill with polyurethane
Apply concrete densifier (to harden areas that were ground down)
At some point in the future, once the slab is dry, apply some sort of vapor barrier over the top of the slab.
Any thoughts or opinions would be most welcome!