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How to trouble-shoot for mold your home for mold.

Updated: Feb 12, 2020

Mold must have moisture to exist and flourish. It also needs a substrate in order to survive.

Mold spores are the offspring of a colony looking for a "soft place to land" where they can start a new home for themselves. On their journey, they float in the air and land on your belongings.

If the humidity level is high enough and/or they find a wet product they will grow there. Thousands and thousands of types exist, therefore they can have different appearances.

To troubleshoot your residence, follow these steps (but please read to the end):

1. Look around your home for visible mold. Look inside cabinets, look for water spots, run water and look for drips, look at walls adjacent to fixtures for discolorations (like closets that back up to plumbing such as showers. Even behind clothes and on shoes.

2. Take a humidity reading inside your home. If you run your a/c or heat frequently, the humidity level should be no more that 55%; if you run it less frequently it should be no higher than 60%. Mold grows well when the humidity is above 50-55%. Plumbing leaks, especially slow leaks, will have mold growth because of the water AND resulting humidity. Humidity can also occur if your a/c is not operating properly. Excessive humidity will feel like you are covered in dew all the time.

3. When you see mold the next step is to figure out WHY. If plumbing is close by (above, below or next to the area) it is likely due to THAT plumbing issue. In the photo below, slight damage and discoloration of the rear bathroom cabinet indicates incoming moisture on the rear wall - a problem of some type and likely mold growth in the cabinet base below or behind the wood covered wall. In this case, the HVAC drain line runs down the same wall from the a/c in the attic - we suspected that the line was sweating due to lack of insulation - and we were right!

2. Look outside your home for reasons that could allow water to enter and feed the mold. Start at the ground and work up. Likely sources, especially for homes over 15 years of age, are high grade that is over or up to the brick, siding or stucco. (Self-flooding high grade shown in the photo below with bushes and trees have allowed too much soil against the house - THIS IS A MAIN ISSUE WITH OLDER HOMES. This allows rainwater that can't run off quickly during our Houston monsoons to back up - and into and under the base plate upon which your walls are built) Mold growth on the "tar paper"/moisture barrier is common and can enter the home's air space through openings such as outlets.

3. Walls - not so much the actual walls, but the "fenestrations" in the walls. Are the window and door trims present? Caulked/sealed? Openings? This is especially important for stucco. I usually don't want to blame stucco for mold in the home air stream, however, depending upon the circumstances, such as cutouts to view substrate, mold can certainly be forced into the air of a home - DON'T EVER LET ANYONE CUT INTO YOUR WALLS TO VIEW STUCCO FROM THE INSIDE WITHOUT MOLD CONTAINMENTS for protecting the air of your home.

Photo below shows poor builder caulk and no homeowner maintenance (no r&r of caulk in 9 years with better caulk)

4. Look at your roof! What condition are the shingles in? Missing some? Pine needles that could allow heavy rainwater to back up and underneath? Many times water penetration is due to the boots that cover the vent pipes and/or flashings around the other protrusions, such as chimneys or furnace flues. Are the flanges raised/lacking nails? Are there water stains or deterioration inside the home near these protrusions? Then it is possible that chronic rain water is making its way inside, running down and also making mold.

5. Attic and HVAC (a/c unit). Water penetration will first hit the attic from the rooftop, and an under-ventilated attic - an overly humid attic - can affect the house air by pulling spores from the attic into the unit, which then enters the air stream. After all, the a/c unit is not 100% hermetically sealed.

Many times the a/c unit is covered with mold, particularly a sealant product that mold flourishes on. Shown below is a unit that has moisture on it, creating a perfect lab for mold AND the ducts are not a good tight fit, causing them to drip on the osb flooring, another "lab" for mold.

What about ventilation - an attic must have good ventilation, both at the soffits and at upper levels - too hot and humid in attic in the summer will allow mold growth. As you can see there a lot of variables here. But de-humidification is a MUST!

The items above are some of the steps we take when we begin our search "assessment" for mold growth and its causes. To complete the search, testing is a valuable source that confirms our suspicions.

Call us at 713-249-8581.

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