possible mold under hardwood floor

[Tile Tom]

Condensation on the cool concrete?

So would a proper installation have been vapor barrier over concrete, then Advantech subfloor, then finish floor?

One day I may rip up the whole thing and do it right. It's what I wanted in the first place but I was overuled by SHMBO.

Nobody's sick but I like a fresh-smelling kitchen. And who knows if there might be some low-grade effects.

Well that debatable. Someone may have another answer but for me I've always been on the no solid hardwood over concrete bandwagon.
When I get a customer that wants hardwood over concrete I always have them pick out an engineered hardwood and glue it down with a quality adhesive with the proper trowel. The glue and the trowel act as a moisture barrier and so far I haven't had any issues.
If I get a customer that absolutely has to have solid hardwood over concrete, I send them down the road. I'm just not willing to go down that rabbit hole.

 

[C.J.]

Basically what you have is an unvented crawl space. Yeah it’s only as tall as your sleepers are but that’s what you have. Since you cut out a hole in your kitchen cabinet you now have a vented crawl space. Just one vent but that’s enough to smell the underfloor nastiness cus naturally any funk is gonna escape through that vent. You got a couple choices. You can either seal up the hole to prevent any funk from venting through the kitchen cabinet or you can open up more holes and introduce air into the space to vent it properly, or at least attempt to.

 

[Megunticook]

Put a coat of Osmo Hardwax Oil on last night. Wood soaked it right up, going to do a second coat tonight. Will post pics. It already looks so much better and all I can smell now is the oil ("I love the smell of VOC's in the morning..."). Love the fact that you can apply this stuff without sanding off the old coat. Plus for my money the look is way nicer than poly.

Anyway this should prevent any further moisture from entering the wood from above. We'll see if it resolves the odor issue (once the oil cures that is!).

And believe me, I'll be maintaining the finish at least once per year going forward.

 

[C.J.]

The wax, like a layer of poly, is what takes the beating. If you apply more before it wears out then you prevent the wood itself from wearing out. Having to apply it more frequently can seem like a pain but the ease of application makes up for that. I usually have to wait until the wife goes out of town before I can take on a task like that.

 

[Megunticook]

Did second coat last night. Looks so much better and should repel dishwater splashes now instead of soaking into the wood. Time will tell if it takes care of the odor--right now the oil is still curing so that's all I smell. Picture below.

Love to go back in time and make different decisions about the flooring over concrete. But I can't really complain, 20 years after we built this house I can honestly say there've been few significant issues or unexpected expenses.

Thanks for all the advice everyone, appreciate it.

 

[C.J.]

Houses are funny like that. Hope all ends well with the funky smell