Top 10 tips to look for water damage and mold in buildings

by / Wednesday, 30 December 2015 / Published in Environmental Testing, Healthy Building Inspections & Testing
Mold in Buildings

Top 10 tips to look for Water Damage and Mold in Buildings

Every year the rains return, soil dampens, leaks pop up, and especially mold in buildings is much more prevalent than during the dry times. This winter’s forecast “El Niño” may bring more rain and possible flooding than California has seen in a decade. Many of our buildings are going to leak in places we were not aware of when the skies were clear.

From State of California—Health and Human Services Agency California Department of Public Health

Statement on Building Dampness, Mold, and Health – September 2011

“CDPH has concluded that the presence of water damage, dampness, visible mold, or mold odor in schools, workplaces, residences, and other indoor environments is unhealthy………….we strongly recommend addressing water damage, dampness, visible mold, and mold odor………… protect the health and well-being of building occupants, especially children.”

Mold is ubiquitous, mold spores are floating around in the air everywhere, all the time.

The total number of spores and specific species can vary wildly. While a small amount of mold is growing in all of our homes, especially in kitchens and bathrooms, this growth rarely triggers symptoms for normal occupants. Significant mold growth due to water damage is of the greatest concern. Hidden water damage can promote significant mold growth that can seriously affect occupant health.

A direct quote from a client:  ….how to find a new place that has a lower chance of having a mold issue” (they generally already have a confirmed issue in their current environment).

The best way, by far, would to have any new home you are considering moving into inspected and tested by a Certified Microbial Investigator.  A standard residential Mold/IAQ Inspection with air and/or surface sampling will typically identify if any significant mold growth is active in a home.

However, the cost of an inspection can be impractical if you are looking at multiple places to move to. Below are 10 tips you can use to identify water damage and mold in buildings prior to purchase or signing a long-term lease. Use these tips to narrow your search and then invest in a professional inspection when you have found the “one”.

Mold in Buildings

No Downspout

10) Drainage: At minimum this usually means gutters and downspouts.

  • Do the downspouts tie into a site drainage system?
  • Are the gutters clogged with leaves and other debris?
  • Walk around the property, is it on a hill?
  • Will water flow toward the building when it rains?
  • Are there drainage culverts, channels, and storm drains?
  • Are these drains clear or clogged with debris?
  • Is there evidence of water splashing onto the building siding?

Proper drainage is key to preventing excess moisture entering a building, a basement, or crawlspace and leading to dry rot or mold growth.

9) Building Envelope – Roof, Windows, Doors, siding, Foundation – Leaks from Exterior

Mold in Buildings

Peeling Paint on Siding

Look at the roof, is it in good condition?

Are the roof penetrations well sealed or is the sealer old and cracking?

Check the ceiling inside for signs of roof leaks, water staining, bubbling, etc.

Look carefully around siding, window and door frames?

  • Is the caulking cracked or smooth and in good condition?
  • Are the frames cracking?
  • Is the paint peeling?
  • Are there cracks or other gaps (where a chimney meets the wall may be one) that may allow water to enter the building envelope?

All are signs that water may be able to enter the building envelope.

8) Leaks – Interior – Plumbing – Fresh water and Drain Plumbing

Water and moisture don’t only come from the outside. The internal plumbing system can leak and provide moisture for mold growth.

  • Check under all sinks, kitchen, bathrooms, laundry room for visible leaks and musty smells.
  • Look around tubs and showers for signs of leaks, mold growth, and bubbling. Tiles that are coming loose are often a sign of moisture in the wall behind.
  • Look at drains for signs of leaks.

7) Condition

Mold in Buildings

Clogged Drain

What is the overall condition of the space? Run down or pristine? Likely somewhere in between, but the general condition can give you a clue how well long term maintenance has been. Shoddy maintenance can allow water damage to fester and mold growth to set in.

6) Condensation

Single pane windows are notorious for excessive condensation.

  • Are window sills cracked and stained?
  • Are window sills dirty or show visible mold growth?
  • Check the back of blinds and drapes for signs of condensation and mold growth.

Older homes, prior to the 1970’s, are usually not insulated. Large pieces of furniture placed against cold, outside walls can be place for condensation and mold growth.

  • Check behind large dressers, bookshelves, or headboards for condensation and mold.
  • Closets that share an outside wall can be very problematic. The excess condensation, limited airflow in a closed closet, as well as plenty of organic material for mold to eat (cotton and wool clothes, cardboard boxes, etc) can lead to a significant mold infestation.


5) Ventilation

Bathroom without sufficient ventilation can be very problematic for condensation. If there is water staining and mold growth or mold stains on the ceiling or walls (some growth in the shower and bath is normal, but not outside of those areas) it is likely condensation may be a problem.

  • Does the bathroom have a good exhaust fan?
  • Is the fan register clean or clogged with dust and debris?
  • Does the bath fan have a timer?

Many older buildings only have windows for bathroom ventilation adding a fan to the window or the bathroom may be necessary to counteract excessive condensation. Kitchens also should have exhaust fans for the range stove that can exhaust excess moisture from cooking to the exterior. Some older buildings only have recirculating fans or no fans at all.


4) HVAC System

The HVAC (Heating, Ventilation and Air Conditioning) system is very important to maintaining both occupant comfort and good air quality. Often the HVAC system is the only way to filter the air we breath inside our homes, although not all HVAC systems have filters! Also, dust and moisture and pests (insects and rodents) can hide out in our ducts and other areas of the HVAC system.

  • If the system has a filter, check it! Is it dirty or clean?
  • Change the filter regularly and use the best quality filter the system can handle.
  • Check the ducts and registers with a flashlight. Are they dirty or clean? Any signs of insect or rodent infestation. Take a sniff, there should be no foul or musty odors.
  • Lift floor registers and look inside for dust and debris.
  • Some systems don’t have ducts, such as radiant floor heat or wall or space heaters.
  • Check wall heaters for buildup of dust and debris. The insides should be clean.
  • A portable air HEPA filter may be advised if the building has radiant heating.


3) Housekeeping

Mold in Buildings

Visible Mold Growth on Baseboard and Wall

Does the building seem “clean”? Remember to check the hard to reach places.

  • Check the tops of door and window frames for dust buildup.
  • Check under the refrigerator. This area can build up quite a bit of debris and mold can grow on the condenser coils.
  • Check behind large items such as cabinets and couches.
  • Mold can easily grow on “Biofilms”. Household dust is considered a biofilm, as it is composed of organic material (skin cells, insect part, cotton and cellulose fibers, pet dander) that mold can use as a food source.
  • Does the building have carpet? Does the carpet appear clean? Is the carpet stained? Carpet can hold moisture from cleaning and spills as well as pet urination, in additional to other contaminants carpet tends to accumulate settled mold spores that come in the air from the exterior.   Carpet can hold mold spores that can become active under conditions of high humidity.

2) Musty Smell

Probably the second biggest “Red Flag” for building you may occupy. A musty smell = ACTIVE MOLD GROWTH. Trust your nose and if there is a moderate to strong musty smell, RUN AWAY.


Mold in buildings should not be visible, with the exception of small amounts around sinks, baths and showers. Sometimes a minor amount around window sills is acceptable. But if you see visible mold growth on walls, ceilings, baseboards, under sinks, etc. this is sign of a significant mold infestation.

As stated by the California Department of Public Health:
visible mold, or mold odor in schools, workplaces, residences, and other indoor environments is unhealthy”.

I hope you can use the above top 10 tips to help find healthy and happy place to call home!


10 Responses to “Top 10 tips to look for water damage and mold in buildings”

  1. Daniel says :

    I like how you pointed out that the biggest way to combat water damage is to have a good drainage system, and that at a minimum that means working gutters and downspouts. My wife and I just bought our home and it’s where we want to spend the rest of our life. Right now the only drainage we have is our gutters so this article has helped me realize how important it is to make sure they are always functioning. I think anyone who is already seeing signs of gutter or water damage would be smart to just have them replaces. New rain gutters would really protect their investment in their home!

  2. Ivy Baker says :

    I like that you pointed out that you need ventilation when cleaning mold. That does seem like a good thing to be aware of if you find any in your home. My home is pretty old and I am scared of finding mold. If I find any I should call a professional to get rid of it for me. That way, I know it is done properly.

  3. Jack Titchener says :

    I like how you talked about the importance of knowing what kind of drainage system you have. My wife and I have to get our house inspected in the next year sometime and we’ve been thinking about doing some remodeling to the roof in the meantime. Thank you so much for the mold tips!

  4. Phil D says :

    Thanks for sharing, mold is a nasty thing to come upon, love the advice that you provided here.

  5. Lynda says :

    Thanks for the article. My last place had a lot of these obvious problems. Something I also noticed when looking at houses was a strong smell of bleach that homeowners had used to (try to) get rid of mould before an inspection.
    A great checklist for me for maintenance issues that need attending before winter arrives, so I can regain my health. 🙂

  6. Annalevis says :

    This is a great post. The reason of permanent black mold is water damage and careless behavior of homeowner provide strength to grow more and also there a lot of side effects of mold.

  7. Anna Levis says :

    That’s a great post. The black molds basically are those which can be more permanent if the water damage do not resolve quickly because if we don’t care for a small water damage then it creates a black mold which can be harmful to your health and your surrounding people. I just want you to read a post about What you need to know about water damage and how it cause damage.

  8. Maggi Garloff says :

    A chronic mold situation was erradicated in our home when the faulty electrical wiring was corrected. I remember reading about a study (wish I could quote it here) whereby it was attempted to grow mold in a faraday cage with minimal effect. However when the petrie dish was removed from the cage and left overnight in the lab, mold rapidly multiplied 800x’s faster than when in the cage. Apparently, mold loves certain emf’s. Seems to me a good item on the to-do list when searching for the cause of mold growth would be to check the electrical wiring and be sure it is up to code with adequate neutrals and grounds.

    Thanks for your good works helping people stay healthy.

  9. Alex Stadtner says :

    Hi Drew,

    You must have seen or heard some pretty bad mold stories. For most folks a little mold indoors isn’t too bad. We often have indoor sources of mold in our refrigerators or in fruit baskets on the counter. And mildew (aka: “Mold”) on the shower tile grout/caulk or around a kitchen sink is almost inevitable. For the latter two examples there’s an interesting debate going as to whether or not exposure to a little mold or bacteria is safer than exposure to the antimicrobials now being put in so many building materials. Many healthy building folks, doctors and toxicologists are actively moving away from antimicrobials so we’ll see how the US industry bends. In the meantime… everything with “MicroBan” is still flying off the shelves.

    Mold spores are everywhere, but I do not mean to say that mold is not dangerous. A little “everyday mold” can be very dangerous for sensitive individuals, and there are some species of mold that are particularly virulent which can harm even the healthiest individuals. Nearly all molds can cause allergic reactions in some people, but a much smaller percentage of molds release neurotoxins that can be extremely harmful to humans.

    You touch on a very important point – ventilation is often linked to indoor air quality and microbial growth. Ensuring proper exhaust ventilation around point sources for indoor humidity is important, as is supplying sufficient fresh outdoor supply air to occupants. And keeping filters and ducts clean and dry is required if the ventilation system is to function as intended and not cause more harm than good.

    Stay healthy,

  10. Drew says :

    My worst fear is finding mold anywhere around my house. I have found that ventilation is a lot more important than expected and can do the best job at preventing mold and mildew to begin with. Thanks for the advice!

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