Excess Moisture

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Does the interior of your property smell damp and musty?  Do you regularly fight mold or mildew.

      A damp musty smell in a house or apartment or an ongoing mold or mildew problem are usually signs of excess moisture.  The odor, mold, or mildew themselves may be the least of your worries.  Excess moisture can attract damaging insects, such as carpenter ants, and/or cause wood rot and drywall deterioration, resulting in serious damage over time.  It can even be a health hazard for children and others with respiratory allergies.
      The excess moisture can either be generated within the interior or result from external moisture that enters the interior.  The highly airtight characteristic of some newer construction sometimes causes more problems than older construction because it prevents the escape of moisture, whether it originally came from outside or was generated inside.
       Sources of interior generated moisture problems include leaky plumbing, bad caulk, or failure to adequately ventilate rooms where moisture is generated.
      Leaky plumbing can include the following:

• under-sink shutoff valves, usually hidden from view in kitchen or bathroom cabinets
• toilets - wax rings under bowls, seals between bowls and tanks, shutoff valves
• leaking of tub and shower valves inside of walls
• valves and lines associated with air conditioning and evaporative cooling units

      If you don't find any leaky plumbing, check out some other sources of moisture generation or retention.
      Although not the result of leaky plumbing, missing or inadequate caulking around tubs and showers allows moisture to get into walls or under floors.  Not only does it take a long time to evaporate in these enclosed spaces, but, if tub or shower is used frequently, the areas never dry out and there is a real potential for considerable hidden damage as well as the breeding of mold and mildew.
       A leaking pan of an interior located air conditioner can result in a continually wet area in the closet in which located.
      Failure to utilize bathroom or laundry room fans can result in problems in those areas.  If necessary to insure their use, install motion and humidity sensors to provide for automatic starting and for running only as long as needed.
       Obvious external sources of moisture are leaky roofs and windows.  These can result in water being trapped in walls or in ceilings where it can cause damage and breed mold even though not visible.  Furthermore, by the time it becomes obviously visible, significant damage to wood and/or drywall/plaster may have occurred.
       A roof-mounted evaporative cooler is an oft forgotten source of water for a roof leak, particular during the dry season.  A leaking pan, valve, supply line, or drain line or an improperly adjusted float can result in the continuous flow of water on the roof and might just find a hole in the roofing that was not a problem for occasional rains.
      If the above possible sources are eliminated as the cause of excessive moisture, it is probably entering through the slab, crawl space, or basement floor and walls.  A dirt crawl space is an obvious possible source.  The concrete slab and basement floor may be less obvious, but you should keep in mind that concrete is actually a rather porous material through which moisture can easily pass.
       The floor of a crawl space should covered with a material that will block moisture from the ground floor.  The vapor barrier film should cover the entire floor and run up the walls to the band joists, using wood strips to seal the edges of the film to the joists. Four or six mil polyethylene film is usually used to seal crawl space floors, at a cost of 2 to 4 cents per square foot.  Cross-laminated polyethylene film, multiple layers bonded together, is much stronger less prone to pin holes.  It usually costs around 10 cents per square foot, but for the typical amount needed will likely add only $50 to the overall cost.  Sources of this better product are listed at the end of this discussion.
      For sealing a slab, the best method is to remove the carpeting, install film over the slab, and re-install the carpet.
      For basement floors and walls, the best do-it-yourself method for stopping moisture is to apply a sealer compound.  The newer water-based sealers are safer and easier to use than solvent-based ones.  Sources of this product are listed below.

Cross-laminated polyethylene film sources
    Fortifiber Corp. (800) 442-2587
    Raven Industries (800) 635-3456
    Sto-Cote Products (800) 435-2621

Water-based sealer compound sources
    Tamms Industries (800) 218-2667
    L&M Construction Chemicals (402) 453-6600

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