Hot Topics: Help! My Basement is Only Half Finished

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If you bought a new home with a basement that is unfinished or only partially finished, it's important to know what the proper process is to sealing it up. Take some tips from our forum DIYers!

Original Post: Half-finished basement help

serjey Member

I purchased a duplex that was built in 1944. It has a half-finished basement, and the other side of the basement has dirt. The house foundation sits on it. I have 6mil plastic, and I want to cover the dirt with it, but the previous owner said if I cover the dirt, then mold might build up under the plastic. Is that true? Are there any other options to cover the dirt?


Highlights from the Thread

Elea_Ela Member

Why not cement it? What's the other half covered with?

serjey Member

The other side is finished. I don't want to invest too much money into it.

Bud9051 Member

Yes, mold may well form under the plastic; mold spores are everywhere and give them moisture and food, and they grow. Cover it with plastic and cover that with concrete, and you get the same. Leaving the dirt exposed simply transfers that moisture to the air and ultimately to the rest of the basement. In addition to the moisture, there are other gases the plastic prevents from entering your living space. Since a major portion of the air you breathe comes from that basement it is best to keep that air as clean as possible.

Use black plastic to keep out any sunlight and seal the plastic a foot or so up all walls and interior supports. If your area has a Radon potential, then consider installing some vent pipes under the plastic.


Furd Member
Mold requires a food source, and I don't think that dirt qualifies. Be sure to seal the plastic to the walls, and I would probably temporarily remove that support post in the middle to run the plastic over the footing block and then replace the post.

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