I have an upcoming project and would appreciate any input. My crawlspace in Maryland had insulation installed upside down (face paper towards ground) and is now rotted/mildewed/falling from the ceiling. Here is the plan I have to replace it all:

Day 1: rent air scrubber. Remove old insulation. Wipe down surfaces with concrobium. Dry vac with HEPA filter
Day 2: Fog crawlspace with concrobium. Replace old entryway
Day 3: Install new insulation.
Day 4: Install new vapor barrier, old one is torn and very thin.

I am also debating whether to replace the vents with automatic ones or to seal them up and pay an electrician to install a dehumidifier.

My decrepit and creepy crawlspace

  • I also plan on using unfaced insulation in the future
    – MadChef
    Sep 20, 2018 at 3:11
  • You've clearly planned this out well, but just to be explicit: get a well-fitting P100 half mask (mold, hantavirus, etc), dust protection goggles (not just safety glasses), gloves, elbow pads, knee pads, crawl suit, and some disposable close-celled foam pads for comfort. Side note: those springy metal rods that hold insulation up sometimes get hidden in the big box store with the Simpson hardware, not with the insulation. Sep 20, 2018 at 14:07

1 Answer 1


Yes, cleaning and preparing for the reinstallation of insulation is important.

Working in a confined area, like a crawl space, requires special protection and ventilation...be careful or hire it done.

Installing batt insulation without a paper vapor barrier is preferred, but it sounds like you’re going to install a vapor barrier after the batt insulation is installed. Vapor barriers are to be installed on the “warm” side of the “envelope”, because of the Dew point.

Yes, the crawl space vents are used to dry out the moisture coming up into the crawl space, but it also dries out the VAPOR coming through the batts and turning into moisture at the Dew Point.

If the vents are blocked, then a dehumidifier may be required where you live, but the vapor barrier is still installed on the WARM side.

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