Inspect for mold in plumbing areas

Inspect for mold in plumbing areas
on January 24, 2014 in Florida Mold Articles

inspect for mold under sinks mushrooms growing

While inspecting under a sink in Miami our inspector found these mushrooms growing.

In this post we will discuss some of the most obvious places to check for mold (plumbing areas) but we will break it down in great detail.
The information in this article is intended for home inspectors, mold inspectors, and home owners. If you need a trained specialist to inspect for mold or moisture in your Miami home or West Palm Beach home click here.  For info on how to inspect for mold in AC ducts click here.

Inspect for mold and moisture under all sinks. If a leak is occurring under a sink it will in most cases be obvious. As soon as you open the cabinet doors under the sink you will detect a musty odor, and likely see moisture or moisture damage under the sink. If you see no moisture run your hand over the pipes to feel for drops of water clinging to the pipes.


Behind Sink Cabinets
In some cases a slow trickle of water will flow out of sight in the spaces between the back of the cabinets and the wall behind the cabinets and result in little or no visible evidence of water. This sometimes occurs when water leaks from the bottom of a sink spigot. In such cases capillary action can cause drops of water to cling to surfaces such as water supply pipes leading to the spigot, or they will cling to the bottom of a countertop, these droplets of water may cling tight to surfaces not let go till they flow backwards behind the cabinets. Over time the buildup of hidden moisture droplets and mold growth behind the cabinets may be substantial.

Often the water will travel in the track located in the bottom of the wall behind the cabinet. This water may travel tens of feet and cause damage to all cabinets along the wall. In one home in Miami the clients had installed 20,000 dollars’ worth of cabinets and granite countertops in their upscale kitchen. 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 to the 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 instillation.


Under Sinks
In many cases moisture will not cling to surfaces for long and flow to hidden locations, but water will drip straight down. Pulled by gravity it will find the lowest point possible and sit under the floor of the cabinet and create humid wet conditions under the cabinet floor where hidden mold will thrive for long periods of time before discovery. This is the most common situation and causes many mold problems.  Many mold remediators can attest to the fact that this is a common issue to deal with.

In either of the two cases if the back of a kitchen sink abuts another room, for example a dining room you can enter that dining 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 this is very good 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 back of the wall. Do not expect much visible damage, the lease amount of staining or separation of the baseboard may indicate a serious problem in the wall.


Wax Ring and flange Area
If a toilet leaks from the wax ring area on the ground floor of a building leaks some of that leaking water may enter the walls around the toilet and result in mold in these walls, if it is on a crawl space the water will flow down into the crawl space and may cause mold and wood decay in the crawl space. If a toilet is on a 2nd floor the water may cause mold in the ceiling under that toilet so inspecting for leaks around toilets is important. As with sinks toilet leaks often go unnoticed. When you inspect for leaks at toilets you can use an old home 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 bolts and toilet attached to it will come loose. This results in the wax seal under the toilet becoming eroded, and this in turn causes the toilet to leak. Such leaks are a common cause of mold in floors and walls around toilets.


Other Common Toilet Leaks
A good test to preform when you inspect toilets for leaks is to feel for moisture at the hold down bolts holding the bottom of the toilet tank to toilet bowl. Also feel for moisture at the water supply pipe that brings water from the wall behind to toilet tm of the toilet tank, these hold down bolts and water supply lines often leak. Though these leaks are typically minor and do not often cause serious mold issues if does not hurt to check for such leaks when inspecting for mold.

When inspecting for mold one of the most common plumbing related mold problems that people overlook is mold caused by leaky shower stalls. While most homeowners focus on the small amounts of mold in shower grout they remain unaware of the fact that the walls behind the tiled shower stalls may be full of mold, moisture, and decay. This common potentials serious moldy condition often goes unnoticed because shower stall leaks almost never result in any visible clues that there is a problem.
Look for missing or cracked grout at the junction between shower walls, and between shower wall to shower floor junctions. Another old home inspector trick that is very important to use 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 with your foot then you know there is decay behind the tile on that wall. 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.

Drains and basins
When a bathtubs metal drain rusts gaps may occur between the drain and the tub basin, this creates a perfect place for leaks to occur, so 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.

Caulking at Tub to Wall Junction
If the caulking between the tub and the wall is deteriorated that area of deteriorated caulking can also be a weak point and result in leaks.  Caulking lines around bath tubs are above the water line so you may assume that not much water enters defective caulking around tubs.  It is true that the caulking is above the water line, but it is also below the shower head, so if anyone stands in the tub and takes a shower that shower water will hit the walls around the tub, and run downward in large amounts and enter the defective caulking areas. This will result in more than enough water penetration for a serious mold problem to occur.

Tub Stopper Area Overflow Covers
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 it 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.

Ice maker water supply lines are thin flexible plastic or copper pipes and they are wound up behind the refrigerator, when the refrigerator is moved for any reason it can be very easy to damage the water supply line. Over time the line may leak resulting in moisture and mold behind the refrigerator, the oven, and nearby cabinets. Unfortunately, often the only way to know if there is a leak behind the refrigerator is to carefully move the refrigerator and check for mold and leaks. Sometimes you may find mold behind refrigerators resulting from active water supply line leaks, other times you may find mold resulting from a past leak that occurred many years ago. While you are checking behind the refrigerator you might as well check behind the oven as well. Because of the proximity of the oven to the refrigerator it is not un common to find mold issues behind ovens. Sometimes such problems are from ice maker water supply line leaks, others it is due to kitchen sink leaks, in either case it is often beneficial to check behind toe oven because while a landlord or past homeowner may remember to repair or hide mold near leak sources they neglect to realize that some of that mold from kitchen source leaks often makes its way behind ovens. 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 cause damage ice maker water supply lines, ovens can tip over if you lean them forward to look behind them, and moving any large object can result in pulled muscles so never look behind these appliances unless you can do so without harming yourself or the house and its appliances.


As everyone knows plumbing leaks are a common cause of mold problems in buildings, however locating the leak can sometimes be easy and straight forward, and at times and can be tricky, in fact difficult and hidden moisture and mold problems can go unnoticed for months or longer.  When we inspect for 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, and West Palm Beach Fl homes.
He is a licensed mold assessor and Certified Indoor Environmentalist as well as a home inspector.


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