Inspect For Mold 
In this post we will discuss the most important place to inspect for mold (plumbing areas).
The information in this article is intended for home inspectors, mold inspectors, and homeowners. If you need a trained specialist to inspect for mold or moisture in your Miami home or West Palm Beach home click here. For more mold inspection tips click here.
Inspect For Mold Around Sinks
Mold Behind Sink Cabinets
In some cases, a slow trickle of water will seep into spaces between sink cabinets and the wall behind the cabinets. This may result in little or no visible evidence of mold or water because the damage is behind the cabinets. How does this happen? In many cases the back splash between a sink’s countertop and the wall behind the countertop will have damaged caulking. In such cases water that splashes onto the countertop flows into the gap between the countertop and backsplash. Often, the leak is very slow and not noticed. However, this type of leak can overtime cause severe mold damage in the wall behind the cabinet.
Example #1
In one property where I did a mold inspection in West Palm Beach I found this problem. The client was senile and unsupervised. She washed her hair in the master bathroom sink instead of the shower. Furthermore, she splashed much water onto the sink countertop when washing her hair. The water flowed through the defective backsplash caulking and caused massive mold damage in her beautiful home’s bathroom. It destroyed cabinets and walls for about 8 to 10 linear foot.
Example #2
Other times plumbing leaks at the base of the faucet will cause droplets to cling to water supply pipes. The water clings to pipes under the sink. Next this water flows into the wall behind the cabinet. This is less common, but I have seen it. Once I did a mold inspection in Miami where the clients installed 20,000 dollars’ worth of cabinets and granite countertops. Because the sink faucet was likely never installed correctly it leaked for a year. Water droplets clung via capillary action to the bottom of the sinks countertop and flowed into gaps between the back wall of the expensive cabinetry and the drywall behind it. This resulted in a $10,000 plus mold problem and the destruction of the $20,000 cabinets just one year after installation.
The majority of the mold problem will be hidden behind the cabinets. However, you may know it is there because water stains will often bleed through the cabinets. Mold will often grow through the cabinets. Odors will also escape and enter areas under the cabinets. You may find all this evidence under the sink by simply opening the sink cabinet doors despite the problem being behind the cabinets.
Inspecting Mold Under Sinks
While inspecting under a sink in Miami our inspector found these mushrooms growing.
When inspecting mold and moisture check under all sinks. First turn the sink on and run the water. If a leak is occurring under a sink it will in most cases be obvious. A less obvious technique is to use your hands. If you see no moisture run your hand over the pipes to feel for moisture clinging to the pipes.
More specifically, rub your hand at the seams where different sections of pile are joined together. In the photo to the right, you will see a P trap type drainpipe. You will also see two rings holding different pipe sections together. These rings are where you want to rub your hand to check for moisture. Also rub the lowest section of pipe where droplets of water are likely to accumulate. In the picture you will see mushrooms growing under this sink in a Miami property I did a mold inspection in.
Check Walls Behind Sink Cabinets
Leaking water will create humid and wet conditions in cabinets under sinks or even under the bottom of the cabinet floor. Under the cabinet floor hidden mold will thrive for long periods of time before discovery. If the back of a sink abuts another room, you can enter that other room and inspect the wall behind the sink. Pay close attention to the baseboard. If the baseboard is separating from the wall by the tiniest amount it is evidence of moisture penetration. Also use a moisture meter to check for moisture in that wall.
If the sink is on an island in the middle of a kitchen, you can do the same thing, simply walk around to the back of the sink and check for moisture damage on the opposite side of the island from the sink. Do not expect much visible damage. The lease amount of staining or separation of the baseboard may indicate a serious problem in the wall.
Inspecting Around Toilets
When inspecting for mold and plumbing leaks around toilets you can use an old home inspectors and mold inspectors trick., First gently push the toilet bowl with your knee. If the toilet moves at all then it is no longer attached to the metal flange under the floor. Often this metal flange will rust, and the toilet becomes loose and moves easily. Over time, such slight toilet movements can damage the wax seal under the toilet.
A damaged wax ring seal may cause the toilet to leak where it attaches to the floor. If such a toilet is on a 2nd floor the water may cause mold in the ceiling under that toilet. Thus, inspecting mold and leaks around toilets is important.
Inspect Shower Walls
While most homeowners focus on the small amounts of mold in shower grout, they remain unaware that walls behind shower tile may be full of mold.
This condition often goes unnoticed because shower stall leaks almost never result in any visible clues.
Look for missing or cracked grout at the shower walls and shower floor. Another old inspection trick is to gently press on the bottom of all four shower walls with your foot. If the wall is soft and bows inward when you push it you know there is decay behind the tile. If a closet or room abuts the shower walls enter that room or closet and inspect for hair line separations between the baseboard and wall. Baseboards separating from walls are an indication of leaks entering that wall.
Bathtubs
Drains and Basins
When a bathtub’s metal drain rusts, gaps may occur between the drain and the tub basin. This creates a perfect place for leaks to occur. Therefore, one should inspect for defects and rust around the drain. If the tub’s basin becomes eroded, pitted, and rusted over time, these areas may also leak.
Inspecting Caulking at Tub Walls
If caulking between the tub and the wall is deteriorated that area can result in leaks. Caulking lines around bathtubs are above the water line so you may assume that not much water enters. It is true that the caulking is above the water line. However, it is also below the shower head. If anyone stands in the tub and takes a shower, that shower water will enter the defective caulking areas. This will result in more than enough water penetration for a serious mold problem to occur.
Inspecting Tub Stoppers and Overflows
The metal flange around the tub stopper control is also known as the overflow cover, or cover plate. Check to see if this overflow cover is tight. If the overflow cover is not tight, water from a full tub can seep behind it and cause leaks. Water will flow behind and under the tub and result in mold growth.
Inspecting Behind Refrigerators and Ovens
Ice maker water supply lines are behind the refrigerator. Over time the line may leak resulting in moisture and mold behind the refrigerator. Mold will also grow behind the oven, and nearby cabinets. Unfortunately, often the only way to inspect for a leak behind the refrigerator is to carefully move the refrigerator and check. Sometimes you may find mold behind refrigerators resulting from active water supply line leaks. Other times you may find mold resulting from a leak that occurred many years ago. While you are checking behind the refrigerator you might as well check behind the oven as well.
It is not un-common to find mold issues behind refrigerators and ovens. Sometimes such problems are from ice maker water supply line leaks. Other times it is due to kitchen sink leaks. Landlords and home sellers may try to hide mold. They remember to repair or hide mold near leak sources. However, they often neglect to realize that some of that mold is often behind ovens and refrigerators.
Warning
If you decide to inspect for mold and moisture behind ovens and refrigerators make sure you only do so if you know what you are doing. Moving refrigerators can damage ice maker water supply lines. You can flood an entire kitchen! This is a big risk so do not do it if you do not know how to do it safely. Ovens can tip over if you lean them forward to look behind them. This is also very dangerous. Moving any large object can result in pulled muscles. Therefore, never move any large appliances unless you can do so without harming yourself or the house and its appliances.
Locating plumbing leaks can sometimes be easy and straight forward, and at times and can be tricky. Moisture and mold problems can go unnoticed for months or longer. When we are inspecting mold and moisture issues one must be diligent so that the cause of issues can be discovered and repaired before they get out of hand.
Author Daryl Watters inspects for mold in Miami, West Palm Beach, and all of South Florida.
He is a licensed mold assessor and Certified Indoor Environmental Consultant.
A Accredited Mold Inspection Service, Inc.
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