Moisture intrusion

Moisture intrusion is a common home issue that can lead to some fairly significant problems over time.  Some common moisture related issues include: structural wood decay, condensation resulting from high indoor humidity, expansive soil which may crack or undermine a home's foundation, softened soil that can lose it's ability to to support an overlying structure, metal corrosion, mold growth, asthma, allergies, etc. Water intrusion can become an expensive problem, if left undiscovered for periods of time.

So how does moisture get into the house?
Moisture and/or water vapor moves into a home in a variety of ways:

• Air infiltration - Air movement accounts for more than 98% of all water vapor movement through building cavities.  Air naturally moves from areas of high pressure to low pressure, such as a hole or a crack in the building envelope.
• Diffusion through building materials - Most building materials slow moisture diffusion to a large degree, although they never really stop it completely.
• Roof leaks - Aging roof materials need repair or replacement, as they will eventually allow water entry.  Storm damage is another leading cause of roof leaks, as well as any roof penetration.  Flashings and sealant should be regularly maintained to prevent roof leaks from occurring.
• Plumbing Leaks
• Flooding - This doesn't necessarily mean a catastrophic flood like the great flood of 2016 in Baton Rouge and Denham Springs.  Flooding can be caused by roof water runoff due to lack of a gutter system.  Seepage into the ground and/or back splashing off the ground can cause moisture penetration.  Also, lack of a kick out flashing where a roof line meets an adjacent wall is a common area for moisture intrusion.
• Household Activities - bathing, cooking, dishwasher use, washing clothes, indoor plants, etc.  These all could be a source of high indoor humidity.  One of the MOST common things we see on a home inspection is where the bathroom exhaust fan and the range exhaust hood vent into the attic.  You can almost guarantee when you find this condition, all the surrounding insulation in the attic will be moist and black.  Venting warm, humid air into an already humid environment is a recipe for condensation and mold growth.  Have you ever been into a bathroom without an exhaust fan and noticed mold spores around the upper corners where the wall meets the ceiling?

So what does this all mean for me? What can I do to control moisture?
Some things you can do as a homeowner to help prevent moisture intrusion is relatively simple.  Monitor your indoor humidity levels (run that A/C!), have adequate ventilation, introduce fresh air from time to time, perform regular home maintenance of roof coverings, fascia, soffits, gutters, landscaping, soil grading, etc.

Here in South Louisiana, moisture and humidity are something we can't avoid.  But we certainly can take matters into our own hands, and get ahead of the game in controlling it as best we can.



Source: InterNACHI