I am remodeling my house and want to make sure that no air/smells come up from under the house. I am installing hardwood (most rooms) and stone/tile (entry/laundry/bathrooms) throughout the house. Heat will come from FAU in attic, with ducts in the ceilings.

Is there a product that I should have contractor put on top of the sub floor (e.g., some type of sealer) that makes sure the floor is impermeable? If so, can I also put this material at bottom of bay inside the wall between the studs--so that the walls are also impermeable with respect to the crawl space?

Basically, I don't want any holes in my walls/floors relative to the crawl space. Is there some reason this is not possible? It seems like it should be possible to make the floor completely air tight.

I do not want whatever material I use to smell either--so it would need to be low or no VOC.

House is 1964 ranch-style in Northern California--standard framing construction with crawl everywhere--2x4 walls.

Hopefully this make sense!

Thanks