Mold Inspection Guide – HHWG

Mold Inspection Guide


    • Getting Started

    • Inspecting a home for mold is primarily inspecting a home for moisture. Building materials such as wood and drywall provide food for mold, however mold will not grow unless surface moisture levels are greater than 70%. Mold spores (microscopic seeds) are always present indoors and out, however we want to assess whether these spores have grown into fully developed mold (mycelium) or if moisture issues are providing a fertile environment for growth. We will begin our inspection on the outside of the house then come inside, working from the bottom of the home to the top. Any potential issue you see outside should be revisited in the interior. Before you get started please grab your phone or tablet. We will use it to take notes, pictures, and zoom in on rooftop areas for further inspection (you can also use a pair of binoculars). If you suspect mold or are going into areas with significant particulate matter, use an appropriate respirator.


  • Landscape and Foundation

    • Check the landscape and drainage of your home as this is where many moisture problems begin.
    • Does water runoff carry toward your house in any area?
    • Inspect where the ground meets the foundation around the house, paying particular attention to areas where water may channel into it and at the corners. Look for the following: cracks, bowing, flaking, discoloration, and paint peeling if applicable. For basements, determine the type of waterproofing, if any, exists from prior records. For concrete slab foundations, ensure the top of the foundation is at least 8″ above the ground, and determine if a vapor barrier and capillary break was installed below.
    • Does your foundation show any signs of moisture entry?
  • Crawlspaces

  • In a national study of crawlspaces, 62% of crawlspaces show visible mold, 67% had wood moisture readings that supported mold growth, and 47% had spores transmitted from the crawlspace into the living area. In other words, your crawlspace is important to inspect.
  •   1) On the outside of the home, look for water runoff from downspouts going into the crawlspace. Be sure downspouts and splashguards lead the water at least 2 feet away from the home and the ground slopes down. 2) Check crawlspace entry and vents for signs of moisture buildup. 3) While the most thorough inspection involves entering the crawlspace and inspecting different areas, you may get a good understanding of the general condition by inspecting the immediate area near the entry. Use a flashlight and zoom feature on your phone and camera to remotely inspect distant areas. 4) Look for a plastic vapor barrier. If the crawlspace has one, do you see any pools of moisture on top or bare patches where the ground is not covered? Does the plastic extend up sides of the foundation walls and are they sealed there with tape or adhesive? If you do not have a vapor barrier, note the condition of the ground. Do you see pools of moisture or damp soil anywhere? 5) If your crawlspace is vented, estimate the square footage of the space as well as vent openings. Does the space have 1 sq ft of venting per 150 sq ft? 6) If your crawlspace has been converted to an unvented, conditioned space, then this solves many problems and is an especially good idea in hot, humid climates. However you still want to make sure appropriate sealing is in place and there is no sign of excess moisture. This includes discoloration, peeling, cracking, and fallen plastic vapor barriers.
  • Basements

  • Basements are usually made from material that moisture can travel through such as cement or masonry, making it common to have a damp basement. A HUD study showed that 85% of basement moisture problems came only after rain or snowmelt, indicating that proper drainage is key to keeping a basement dry. 65% of basement leakage was due to improper grading from construction or settling, while 25% was from gutter drainage. Ensuring proper grading and drainage outside is the best way to keep a basement as dry as possible. In areas with considerable rainfall this is particularly important.
  • Roofs

  • The roof is another key moisture entry point we will inspect. Use your phone, tablet, or binoculars to look at the following areas for signs of prior repair, gaps, cracks, or shifted roofing. If you do see any of these indicators, note them and inspect the same area inside.
    • Chimneys – look for salt deposits. This may indicate a moisture problem in older chimneys.
    • Skylights
    • Valleys and corners
    • Dormers or projections out of the roof
    • Vents and edges
  • Siding and Windows

    • Inspect the siding for any signs of moisture, including paint warping or peeling, discoloration, gaps or cracks, and shifted siding.
    • Pay particular attention to the top and frames of windows. Look for caulking around the edges and note any area where it is missing, peeling, or shows signs of moisture intrusion. Ensure the metal flashing is appropriately installed and look for signs of moisture accumulation around it.


Use your notes from the outside inspection to determine where to focus your investigation inside.
  • Basements

  • Basements require careful inspection both inside and out. Remember that most basement issues are from improper drainage outside, however we want to find where moisture may be accumulating or causing any mold growth.
    • Inspect where the frame of the wall meets the foundation for moisture or stains.
    • Look at the walls for stains or discoloration.
    • Investigate flooring for signs or previous water accumulation. If you have carpet, pull up a corner and check for dampness or mold growth.
    • Inspect windows and doors leading outside for rot, warping, paint peeling, or other signs of moisture accumulation or infiltration.
    • Investigate plumbing pipes for any leaks.
  • Bathrooms

  • Bathrooms are a high moisture area and a potential root cause of mold issues. Carefully inspect the below areas and ensure you use your bathroom fan regularly.
    1. Bathtub and shower: Examine tile for cracks or mildew and caulking all around. For older showers, fill the stall halfway with water and let it sit, noticing if water has leaked through the tile or drain.
    2. Sinks and toilets: Inspect beneath the sinks while running water and search for leaks. Review caulking around openings. Gently rock the toilet back and forth to make sure there is a strong seal. Look for signs of moisture damage around the base and behind the toilet.
    3. Walls, ceilings, and floors: Look for signs of mildew, staining, peeling, or cracking.
  • Laundry Rooms

  • Laundry rooms are another high moisture area in the home. Carefully inspect the below areas and ensure you use your laundry fan or ventilate regularly. Be sure to check all plumbing connections for leaks and the floor for moisture.
  • Kitchens

    • Check the floor for any signs of moisture accumulation – especially around the refrigerator and dishwasher.
    • Inspect the walls for stains, peeling, cracks, or warping.
    • Look at the plumbing under the sink while running the water for leaks and signs of moisture in the cabinets.
  • Attics

    • Attic moisture problems stem from roof leaks and inadequate ventilation. Be sure to wear a respirator in the attic as insulation, mold, and other particles can be harmful to your lungs (another reason to seal your attic from your living area). If the attic is inaccessible, you are uncomfortable walking on the joists (wood framing on the attic floor) or you cannot walk on them without compressing the insulation, stay at the entry and inspect from there. Remember between the joists is the ceiling below which will not support your weight. WE ARE NOT RESPONSIBLE FOR ACCIDENTS THAT OCCUR WHEN INSPECTING THE ATTIC.
    • Ventilation: Ensure the attic is vented at least 1 square foot for every 150 square feet.
    • Insulation: Any water leaks on cellulose insulation will show a dark or damp spot, while fiberglass insulation will compress and look like a sponge.
    • Roofs: Look for signs of leaks such as discoloration, peeling, dark spots, or stains. If you noticed any prior repairs, cracks, or issue areas outside, be sure to spend extra time inspecting them along with skylights. Inspect any other roof penetrations such as chimneys and exhaust, and anywhere the roof changes direction.
  • Corner Rooms or Above Garage

  • Corner rooms and rooms above the garage are often the coldest room in the house because multiple sides are exposed to the outdoors. The colder a room is, the higher the relative humidity since cold air can hold less moisture than warm air. Be sure to allow for enough ventilation between furniture and exterior walls, and bring in additional heating to help reduce the opportunity for moisture issues.
  • General Walls, Ceilings, Floors, Windows, and Doors

  • While the above rooms are the most common areas where moisture issues occur, a thorough inspection of other areas is a good idea. Investigate each wall, ceiling and floor for discoloration, staining, watermarks, peeling, or other degradation that could indicate mold growth, particularly in areas with little ventilation. If doors or windows do not close properly, it may be due to water damage. Pay attention to the area around both to see if any moisture intrusion has occurred. Windows often build up condensation, especially if they are single pane or aluminum framed.

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