Mold and Moisture Problems in Old Homes

Mold and Moisture Problems in Old Homes

Home Inspections

“Mold and Moisture Problems in Old Homes" is part of our series on

Old Home Inspection Checklist 

As you inspect the basement of your prospective home, one of the most important issues to keep in mind is the level of moisture. Moisture problems in old homes can be particularly difficult to fix, especially in homes with unfinished/dirt basements, and stone or brick foundations. As you’re surveying the property for any potential problems, the presence of moisture and mold should be a bit of a red flag. While not necessarily a reason to panic or walk away from a home you otherwise love, mold remediation and treatment of moisture issues in older houses can stack up to be a big project once the home is in your hands. Here’s everything you need to know about moisture problems in old homes: humidity, mold, how to prevent it, how to fix it, and when you should find a professional to help.

Mold: What’s the Big Deal?

Mold and mildew are organisms that exist in nature to help break down dead matter like trees and fallen leaves. They spread via airborne spores, which can enter an indoor space through the air or by attaching to a moist substance or object. Since mold spores are airborne, they are impossible to eliminate from any area completely. However, these spores can only grow or spread in the presence of moisture; so, the only way to tackle a mold problem is to tackle the underlying moisture or water problem. 

Since the function of mold is to help decay dead matter, a persistent mold issue can be dangerous to the longevity of your home and sentimental items. Mold gradually deteriorates whatever it grows on, so if you notice it growing, it needs to be fixed sooner rather than later. Additionally, mold can cause health problems in sensitive individuals. Allergies to airborne mold spores are quite common; when inhaled, mold can also worsen symptoms of asthma. In rare cases, certain types of mold can be toxic.

How to Maintain Healthy Moisture Levels

  • Treat Floods & Leaks. Unwanted water and moisture in your home can cause damage. Fast and thorough cleanup and treatment of floods and leaks prevents heightened moisture levels from growing into bigger issues.
  • Clean Gutters. Keeping rain gutters clean prevents unnecessary overflow and leaks from draining into your home. Regular maintenance on gutters is essential.
  • Proper Ventilation & Circulation. Vent appliances to outdoors if possible. Running a fan, or simply opening doors and windows, creates airflow and helps to prevent water from collecting and causing problems.
  • Air Conditioning & Dehumidification. A/C and dehumidifiers can reduce the amount of moisture in the air.
  • Insulate Cold Surfaces & Prevent Condensation. Cold water pipes and other cold surfaces can cause condensation to gather. Insulating these surfaces prevents the collection of moisture.

What to Look For

Moisture problems in old homes can be present with or without visible mold, so you should be on the lookout for these signs and signals:

  • Leaks
  • Musty odor
  • Condensation
  • Water stains on the floors/walls
  • Visible mold

Uh Oh! Watch Out for Hidden Mold

If you encounter signs such as odor and water stains, but can’t track down any visible mold, it’s possible that you’ve got a hidden mold problem on your hands. When lost of moisture is present, mold can grow in places undetected in plain sight. Mold can flourish in places like the back of wallpaper, under drywall, on the back side of paneling, on the upper side of ceiling tiles, and other places where air and moisture can become trapped between two surfaces. If you think you have a hidden mold issue, do not disturb the places where you think mold may be growing. Since mold can be a health hazard, it’s best to call in a professional to help get a grasp of the problem.

Sources of Persistent Water Issues

If you encounter a wet basement in an old home, there are steps you should address prior to hiring a waterproofing expert. Many contemporary waterproofing techniques can be damaging to old homes with brick or stone foundations. According to William Kibbel III, a celebrated old home restoration expert, delicately correcting the source of the problem is crucial. He says:

Too often folks tell me that the waterproofing contractor they hired only offered a single option for correcting a water penetration issue. That option just happens to be the most intrusive and costly. If I were considering hiring a contractor to fix my wet basement, I would hope that the causes of the water were evaluated and remedies suggested. Here are some of the most common sources of water entry:

  • Inadequate or clogged gutters and downspouts not extended. There's a significant amount of water that falls on a roof during heavy rains. This needs to be collected in a maintained system that discharges the water well away from old house foundations.  
  • Improper grading. The soil near the foundation should slope away from the house.  Current standards require that the ground should slope down at least 6 inches within 10 feet of the foundation. Many homes with basement water issues have been corrected by simply adding soil around the perimeter and grading it to shed the water away. Care should be taken if adding soil. Dirt should be kept well away from siding, trim, or basement window frames.  
  • Foundation maintenance. Old stone and brick foundations typically need some re-pointing, when the old mortar has worked its way out of the joints. Many stone foundations also need the interior mortar coating restored.

How to Fix Serious Water, Moisture, & Mold Problems

The first step to fixing moisture problems in old homes is usually to identify any underlying structural problems. It’s common to think that remediating a mold issue is as simple as cleaning up the mold; that’s not usually the case. To ensure the safety of your future home, it’s important to take a hard look at any underlying problems like the ones outlined above. Next, determine what treatments or renovations are needed to reduce the moisture in your home (in addition to cleaning and repairing any damage done by mold). Generally, these will include installing proper drainage, creating ventilation systems to keep air circulating through and out of the house, and dehumidification of the air to remove airborne moisture and mold.

Since mold can be dangerous to your health, these are usually not projects you should take on by yourself. Always call in a mold remediation or water damage specialist to help you safely and effectively tackle the problem, to ensure the health and safety of yourself, your family, and your home, for years to come.

Much of the information in this article was adapted from the EPA's Guide to Mold, Moisture, and Your Home.

This is a guide for the prospective homeowner to help determine the condition of the house.  Some of the checkpoints on this list might be deal breakers or they might be just part of the journey you’ll need to address when fixing up or restoring an older house. This is not an official document, but a guide to assess the kind of work involved in fixing up the house and perhaps to use as bargaining points when discussing terms with the seller.

Please have a certified Home Inspector go through and submit a report on the house before you purchase it.

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