Mold, Mold, Everywhere

Having flipped 30 homes, I was a very active participant in my real estate agent CE class called "Mold, Meth, and Radon."  I definitely exceeded my quota of comments and questions!  The class was taught by a very competent home inspector.  This is my summary of the Mold section from the perspective of a rehabber:

Mold is everywhere in the air and on surfaces. It plays a vital role in breaking down organic matter. Out of control growth in homes is generally just a matter of elevated moisture. 

In one 4-plex the instructor inspected, 3 units were fine, but the fourth mysteriously had mold all over all the walls. After finding multiple big pots in the kitchen and talking with the owner, the inspector found out that the family had a vending business and boiled several batches of tamales to sell each day - keeping the humidity very high in the home. Kitchen exhaust fan to the rescue!

About 1/3 of the 70,000+ fungus/mold species are considered "black" and so the terminology is not very helpful, especially since there are many people with strong reactions to "non-black" mold as well as people with no reactions to "black" mold. Bottom line - high concentrations are bad.

Even though mold/mildew/fungus/mushrooms in the home is bad, there are no federally mandated guidelines because mold and the spores are EVERYWHERE.  

This being said, the EPA suggests that active mold colonies of 10 square feet or less can be cleaned by the homeowner. Over 10 sf should be treated by a remediation company. Don't just use bleach but use a bathroom product that has fungicide in it.

"Dry-rot" is the desiccated evidence of an active wet fungal feast. The eves, for example, get wet, get munched on, and then dry out again.

Because of heat transfer, aluminum single pane windows are the worst offenders for condensation and mold growth. Replace if possible.

Water only wicks up the sheet rock from a flooded basement 18 inches because of the weight of the water. That is why you see 24" of sheet rock removed sometimes. If mold is above 18", then the source is elevated humidity in the home or it is coming through the walls.

If there is any evidence of groundwater problems, or effervescence (white minerals) on the basement concrete or masonry walls, it is better not to use wall to wall carpet over a concrete basement slab. (In these cases, do tile or linoleum.) 

Put bleach in floor drains regularly to minimize mold from that source.

Make sure the dryer vent and the bathroom fans are vented to the outside of the home, not into the crawlspace or attic.

Be sure to insulate walls if you are opening them up. The basement walls get cold and often promote condensation.

Consider gutters and install downspout extensions to get rainwater AWAY from the house.

If necessary, add soil against the foundation to make the grade go away from the house. 

Some people put carpet in crawl spaces. Get those out of there. They become mushroom heaven.

A black plastic crawlspace vapor barrier is good, but if you install it, it should be sealed against the foundation on all sides to work properly.

Inspection companies can do air tests or swab tests for mold, but these are very expensive. The instructor said the better thing to do is to just find the moisture source and fix it.

-Steve Theobald