In the utility roon of our house we have lanoleum flooring. In an area of this room next to the back door (leading outside), a grey color is showing through a section of the flooring about 4' by 2'. When you look at it, it looks sort of like the foundation showing through, but I've always assumed it was some sort of mildew coming from outside. Does anyone know what this could be and if there's anything I can do about it? If I cut this bad section out and have it replaced should I put something on the foundation to prevent it from coming back? Any help would be appreciated?
If you want to prove whether the problem is mildew or something else, why don't you use a mildew-killing product on 1/2 of it and then see if there's a difference between that and the other half. That should help you determine what you need to do next.