Mold Inspection: How is it Done?

The inspection process includes a general understanding of the building, including age, number of stories, roofing and siding type, and presence of basements or crawlspaces.

The behavior of moisture in the structure is the critical component of the assessment. The grading around the building should be reviewed to ensure the water flows away from the foundation. This is especially important in the area of roof leaders and drains. Some grading issues are a challenge by definition. For instance, if a home has a walk-out patio door on one side of the basement and the rest of the basement is below grade, this implies that the grade slopes toward the house on the other side.

Water infiltration through the skin of the building is a common source of moisture damage. Evaluate the condition of the roof, siding, windows and doors. Inspect for evidence of moisture damage in the areas of these structures on the building interior. The roof condition can frequently be observed in the attic, or by evidence of damage on ceiling drywall or acoustical tiles. Evidence of water damage around doors and windows can be subtle, but look for water stains, wrinkled paint and peeling drywall tape.

Perhaps the best known sources of moisture damage in a building are plumbing system leaks. Potable hot and cold water lines can fail catastrophically, or leak slowly through a pinhole or bad fitting. Potable water is classified as Category 1 clean water, and may not initially support biological growth. If materials can be dried within 24-48 hours, growth may not have an opportunity to commence. It is important to note, however, that if the water comes in contact with an existing fungal condition, additional growth will commence almost immediately.

Leaks from sanitary sewer lines are considered to be contaminated at the outset of the event. Category 2 water is classified as gray water, and includes water from washing machines, dishwashers, sinks, and toilets that did not contain feces. In some cases it may be possible to salvage materials affected by Category 2 water, but the cleaning would have to commence immediately.

Category 3 water is classified as black water and includes water from toilets with feces, sanitary sewer lines, floodwater that has been in contact with soil, and seawater. Porous materials that have been in contact with Category 3 water must be discarded, since it is possible that a number of virulent bacteria may be present in the water. In many cases even semi-porous materials such as wood sheathing and particleboard will not be salvageable.

Basements and crawlspaces are notable locations for biological growth due to several factors, including water infiltration through the foundation, plumbing leaks, and condensation on the cold surfaces of masonry walls and floors. It is important to realize that relative humidity at the layer of air along a cold surface will be higher than in the middle of the room. A number of common fungi can thrive on these surfaces if the relative humidity exceeds 75%. It is not uncommon for the cold surfaces to support a moderate biological population that is not readily apparent, until a water event causes the existing population to explode.

The basement moisture conditions were usually not a big deal in the past when the spaces were unfinished. But by finishing basements with drywall, fiberglass insulation and (ugh) carpet, we have added a substantial quantity of mold food to a suitably moist environment. Watch out.

Crawlspaces are usually ok as long as they are reasonably dry and have adequate cross-ventilation. When there is water infiltration and the ventilation is not adequate to remove water vapor, biological growth can develop on the wood joists and fiberglass insulation. It is becoming increasingly clear that fiberglass is simply not a suitable insulation material in a space that is open to ambient moisture.

The porosity of the materials affected by moisture is the primary consideration is determining whether a material can be salvaged. Porous materials such as carpet, fiberglass insulation and drywall readily support mold growth, are usually impossible to thoroughly clean and should be discarded if they have developed mold growth.

Pay special attention to very porous materials such as carpet and insulation in a moist or humid environment. There can be substantial biological activity with no visible evidence. Microorganisms enjoy an environment with mass and depth. In the plush matrix of these materials, moisture conditions are stable and no drying air currents are present.

Semi-porous materials can usually be cleaned and salvaged, unless the water damage has affected the structural integrity of the component. Wood materials such as dimensional lumber, plywood and most finished wood surfaces are reasonably resistant to moisture damage. Composite wood materials such as particleboard, oriented strand board and chip board are much more likely to absorb moisture, develop structural problems and support a biological population within the material matrix.

Hard surfaces such as metal, vinyl and painted masonry can usually be cleaned and salvaged. Unfinished masonry is classified as semi-porous, and can generally be cleaned by thorough HEPA vacuuming. Unfinished masonry frequently benefits from encapsulation with an antimicrobial sealer after the unfinished surface has been cleaned.

On some materials there is the possibility of staining from certain fungi types, especially on plastic surfaces that contain the hydrocarbon that the fungi can colonize. We have seen examples of basement moisture where the only material that grew mold was the vinyl backpacks. This is also why vinyl siding requires frequent cleaning, especially on the shady side of the house where the sun don’t shine. The vinyl is obviously a favorite mold food.