Wet or Damp Basements
by Building Inspector and Indoor Air Specialist, Dan Schilling
© Copyright 2002 Residential Inspections LLC, All Rights Reserved
It's quite common these days to find homes with basement areas converted into finished spaces. It seems everyone wants as much livable space as possible in their homes. Often, when remodeling projects are performed in basements, there is little consideration toward moisture concerns. This has caused considerable damage to personal property, the structures of homes, and many illnesses related to indoor mold contamination. Furthermore, the quality of the air in the basement will directly affect the quality of the air in the rest of the house.
Proper ventilation is a must for all finished rooms. Many basement remodeling jobs, particularly those done without permits, do not have sufficient ventilation. Some have supply vents, but lack an air return to allow air to get back to the heating/cooling system. This can cause a basement room to be cold in the winter months, and damp and musty in the summer. This can be uncomfortable, as well as, unhealthy. All basement passage doors should open with ease and have a least 3/4" of clearance between the bottom of the door and the floor covering.
If installing carpet, be sure the carpet is suitable for installation over concrete to help prevent mold contamination. Ask your carpet supplier. It is also wise to seal the concrete flooring with a quality concrete paint or sealer. This will help to penetrating vapor from coming up through the floor and into the carpet.
Storage of Personal Property
If you will be storing items in your basement, you'll need to use a little wisdom. Never store cardboard boxes on the concrete floor. All items, cardboard or not, should be stored up off the floor, particularly if the floor is not sealed. When storing things on shelving, do not push items tight against the back wall. Leave a breather space behind the items, particularly if the walls are bare concrete.
What if my basement is unfinished, does it still matter?
I have seen mold spread like cancer all over building materials and personal property in basements. It does not matter whether the basements are finished or not. Finished basements are perhaps more vulnerable but all basements are subject to problems.
Most basements or rooms that are located below grade will require the use of a dehumidifier to keep indoor humidity levels below the acceptable 50% level. Certainly during the spring, summer and fall months. Some newer homes may need to run a dehumidifier during the winter months as well. A new home can have as many as forty tons of water moisture in the concrete and other building materials which make take a few years to dry out. If you smell a musty or mildew type smell, it is too late. You already have a mold problem somewhere. You should have your home inspected for areas of mold contamination and remediate the problem before you dehumidify. Why? Because many types of molds will go into a self-defense mode when the air dries out. They will sporulate excessively in an attempt to perpetuate the species. Depending on whether the mold is allergenic, pathogenic or toxigenic, this sporulation can cause significant indoor air quality problems, as well as, spread contamination further.
Expect Water Problems
It must be understood that all basements, finished or not, are “below” grade and often near an underground water table. Studies have shown that it is not a matter of whether you will have water enter your basement, but “when”. Improperly installed or maintained gutters and improper drainage grading are the primary reason for basement water incursions. Moisture can enter as a liquid or as a vapor. When entering as a vapor, it is rarely noticed, but either way, property damage and mold contamination can occur rapidly. Take every measure possible to prevent moisture entry. If it has already entered and especially if you smell any musty odors, consult an inspector who specializes in mold and moisture entry issues.
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