Log in to enjoy membership benefits from The Family Handyman.
Sign up today for FREE and become part of The Family Handyman community of DIYers.
Water is always the cause of mold and mildew, but finding the source of the problem can seem like an unsolvable mystery. Follow our tips for using some handy gadgets and basic detective work to find and eliminate your mold and mildew problems for good,.
If you see mold near water pipes,
waste lines, icemaker lines or plumbing
fixtures, chances are the mold is
feeding off a nearby leak. Let the
water run while you check the pipes
and surrounding area for damp spots.
Remember that water can travel in
any direction—down, sideways or
even up when it wicks into absorbent
material like drywall—so the actual
leak may be some distance from the
Mold can be an early warning sign of a
moisture problem inside walls or ceilings
that could cause an expensive problem
like wood rot. Avoid the temptation to just
wipe the mold away and forget about it—find and stop the water source.
If mold is growing on an exterior wall
or ceiling, first look for a leak in the wall
or roof. Measure from the moldy area
to a reference point like a door, then
find the spot on the other side of the
wall or ceiling.
Closely inspect nearby vents, roof
flashing, decks, window wells and anywhere
wood is rotting. Look for ground
sloping toward the house and downspouts
emptying next to the wall. If the
ground around the house gets too wet,
moisture will wick into the foundation
or slab and become persistent dampness.
If mold forms on the ceiling under a duct or register and
there's no sign of a roof leak, badly insulated ductwork may
be the cause. Warm, moist air condenses and forms water on
ducts carrying cold air through the attic or crawl space. The
condensation is a sign that the duct is uninsulated or missing
a vapor barrier. Eventually the water saturates the insulation
and drywall and mold spores (which are everywhere)
In cold weather, the reverse happens. Moisture forms anywhere
warm air escapes—for instance, at unsealed joints
between duct sections.
Most mold is unmistakable, but sometimes
small or largely hidden growths just
make a surface look dirty.
For a quick test, dip a swab in diluted
bleach (1 part bleach, 16 parts water) and
dab it on the wall. If the spot quickly
lightens (or keeps coming back after
cleaning), assume it's mold.
Mold test kits are available that detect
the presence and identify the type of
mold, but they won't help determine the
cause or what to do about it.
If you need to build or rebuild an
area where moisture has been a problem,
use materials that resist mold
growth and aren't affected by
water. Construct walls with
pressure-treated wood and
rigid insulation and cover the
walls with paperless drywall,
which has nothing for mold to
In areas where mold
might grow, such as basement walls,
spray the surfaces with an antimicrobial
treatment. Paint walls with
mildew-resistant primer and paint or
add mildewcide to your paint.
Warm air seeks gaps in the insulation,
and when it hits colder surfaces as it
flows out of or into the house, water
condenses—which then feeds mold.
These spots often occur on outside
walls near floors or windows, at corners
and around outlets and lights. If
the mold disappears after cleaning it
and lowering indoor humidity with a
dehumidifier or vent fan, just keep an
eye on it. If it recurs, open the wall and
fix the problem.
To prevent mold around the tub or shower,
spray the wall
with an antimicrobial treatment, then
seal the grout with two coats of grout
sealant to keep water from wicking in.
If the mold is extensive and tiles come
off, rebuild the wall with cement board
tile backer and new tile.
If the wall is sound but the mold
stains won't go away, try
regrouting. Scrape out the caulk
and stained grout, spray the wall
with antimicrobial treatment, regrout
and caulk and then coat the whole
wall with grout sealant.
Avoid last-minute shopping trips by having all your materials ready ahead of time. Here's a list.
Share what's on your mind and see what other DIYers are thinking about.
May 12, 3:38 PM [GMT -5]
I forgot to mention that our big concern is whether or not this mildew/mold is harmful to our baby. How can we find that out when we can't go buy a mildew testing kit here? A simple way is the only way to go here since we live in a developing country.
May 12, 3:33 PM [GMT -5]
Hi! My husband and I live in Madagascar. We just noticed that we have mold or mildew (not sure of the difference) in our baby's room. The wall has a lot of moisture but we are not sure where it is coming from especially since our walls are made of cement. What is our next step in finding the underlying cause because things that get "fixed" here are only bandaids?
November 21, 11:33 PM [GMT -5]
Hi panvanchan, I've been spraying a mixture of 1 part baking soda and 3 parts vinegar onto my wooden chopping board when it's clean and dry to prevent future molds. And so far, it has been working for me. Thus, it should work for your wooden windows too. However, I agree with this article that you need to find the root of the mold problem and tackle it from there. Perhaps you could replace the rubber seal with a plastic one as water runs off its surface more smoothly, thus disallowing the wooden edge to absorb moisture (either from the shower or outside rain) and hence preventing mold.
August 02, 9:01 AM [GMT -5]
MY HOUSE SMELLS LIKE MOLD
We have seen it many times. An owner or family goes away for a period of time, whether a few days or a few weeks. They return to their home to find that their home smells like mold. There is no apparent source of water, but the smell is noticeable, and the owner has just concerns regarding the cause.
Mold growth requires an event to have occurred. This event may be major and obvious, or something that requires a thorough exam to determine what exactly happened. If the event is substantial, like a broken pipe, hot water heater, or a/c condensate leak, the inspection is pretty quick, and the answer definitive. There may be noticeable water damage and with a dwelling closed up for a period of time, the smell of the resulting mold growth can become concentrated and very noticeable.
There are other times, however, when there is no obvious sign of water damage, but yet there is a definite smell of mold. In this case, a more thorough investigation might be required. A moisture meter is typically used to moisture map the building or infrared photography can be used to locate moist, or cooler areas of building components. All this is done to find hidden moisture and mold. Sometimes a leak under a kitchen cabinet might allow water to remain trapped under the cabinets or tile. Sometimes a leak from the outside results in moisture that is contained behind baseboards. Wood or tile flooring can conceal water, and wet carpet from a slab leak might not be obvious. Leaks in A/C ducts could cause excess condensation in ductwork and leak into attic spaces. The investigator is looking for wet material, and the source of the water that caused it to get wet. In each of these scenarios, you may never see the water, but you smell the mold.
A qualified restoration company might well find the cause of the moldy smell, but sometimes they are stumped. In this case, you might call a “Mold Assessor”. If a mold assessor is called in for the investigation, he will be looking for all of the above once again, and then probably take air samples from the suspect room or rooms, as well as an air sample from outside the dwelling for a comparative analysis. He might also take a sample from a part of the dwelling that does not have that moldy smell. The object of this inspection would be to determine if you have an elevated airborne mold condition in your home.
If an undetermined water leak is suspected, you could call a “leak detection” specialist. Some plumbing companies have the equipment and expertise to do this, but many plumbers use specialists themselves. A very small leak in a pipe is often difficult to find. Sometimes the pipes need to be charged with compressed nitrogen. When this gas leaks through a break in a pipe, the noise is detectible with the use of sound monitoring equipment. Leaks that are difficult to find are often detected using this method.
If there is even a small amount of water intrusion into a property, and if the relative humidity goes up, and exceeds 65%, and if the temperature inside the building becomes elevated, there is the potential that a serious mold condition could develop. In such a situation, mold growth could be observed growing on anything organic in the building. Once these conditions occur, the whole property is usually treated for the mold contamination, and many content and porous items may be deemed unsalvageable.
Mold can remain dormant in a building for many years, and remain inactive until it becomes wet again. If it remains dry and dormant, it will not smell. The smell of mold is the result of the off gassing of the mold, or fungi, digesting whatever it attacks.
The State of Florida now regulates the mold inspection and remediation industry. It is important to know that if you hire a “Mold Assessor” or a “Mold Remediator” to perform services, you should verify their licensing credentials.
Restoration Xperts, http://www.restorationxperts.net offers its “Mold Remediation” services to property owners in Broward and Palm Beach counties in Florida. For quick help with your emergency 24/7 its crews are available to respond to water damage. .
Restoration Xperts Inc.
1130 S. Powerline Rd. #101 Deerfield Beach, Fl. 33442 561-737-8673 http://www.restorationxperts.net
March 07, 9:05 PM [GMT -5]
Hi, any tips for effective cleaning of mold off wooden windows, such as on a bathroom window along the wood's edge where there's a thin black rubber seal before it meets the glass pane? I've used dish soap & water, but am wondering if there's a better way.
Log in to enjoy membership benefits from The Family Handyman.
ScreenName My Account (Log
Log in or
Get timely DIY projects for your home and yard,
plus a dream project for your wish list!