6 Tips for Healthy Below-Grade Spaces

The trick to healthy below-grade spaces is keeping the area dry and free from mold—or anything that may be a food source for mold.

Jeffrey C. May, owner, of May Indoor Air Investigations, LLC., in Tyngboro, MA, agrees with the EPA and the Basement Health Association of how to keep a safe, dry and healthy basement.  He outlined tips for keeping healthy below-grade spaces that coincide with the practices of basement health pros.

Dehumidify your basement

May says high humidity is the leading cause of mold growth in the basement.  Mold and mildew flourish when the relative humidity level is above 80%; therefore all basements—finished or unfinished—should be kept at or below 50% relative humidity. In order to maintain that humidity level, May suggests using a dehumidifier and measure the humidity level often.  He says the humidity level should be measured independent of the dehumidifier.  He suggests using a thermo-hygrometer such as Humidity Alert from Therma-Stor.com/.

A basement exhaust is not a dehumidifier

Sucking the air out of the basement will not maintain the proper humidity levels in the basement. When you pull air out of a basement, it pulls make-up air in either through the exterior or from the upper levels of the house. On a hot and humid day, the air from the house and the outside air will have a high moisture content thus introducing more moisture into the basement through the make-up air.

Keep a finished basement warm in the heating season

Simply put, when air cools, its relative humidity levels increases. The best way to maintain a 50% relative humidity level in your basement is to keep it warm in the heating season.  Most people are prone to turning down the heat in the basement if they are not using it. However, when the air is warming and cooling the air will actually create more moisture that may lead to mold and mildew growth.  May suggests keeping the basement consistently warm at least at 58 to 60 degrees F in the heating season.

Get rid of basement carpeting

There are inherent problems with carpet in the basement.  Carpet captures biodegradable dust and can be a breeding ground for mold.  While a basement should be treated like part of the house, it is not the same as the upper levels of the house.  There are different issues that happen in the basement environment and the same building principles don’t apply the same below-grade.  May recommends tile or vinyl flooring instead of carpet to eliminate the potential problems.

No fiberglass insulation in the crawlspace

Fiberglass insulation doesn’t work very well below-grade.  It is

In an unfinished basement, store belongings properly

A common scene in an unfinished basement is a bunch of cardboard boxes full of seasonal decorations and keepsakes sitting directly on the concrete floor.  Anything biodegradable on the porous concrete floor may lead to mold problems. If there is ever water or moisture problems in the basement these boxes should be off the floor on a metal or plastic shelf.  The shelving should also be at least 18 inches away from the foundation wall and 6 inches off the floor.  If you have to keep cardboard boxes on the floor, May suggests putting down a foil-laminated sheet of polyisocyanurate foam insulation on the floor and up against the wall to protect the boxes from the concrete slab and foundation wall.