Mold on Different Surfaces
Mold can behave very differently depending on the type of surface that it is
growing on. If you are taking surface samples of mold in a room, it is important
to take a unique sample for each different type of material that you suspect
mold could be present on. The material that the mold growth is located on
can also have a significant affect on what type of mold remediation effort is
No matter what the material type may be, if the surface is water damaged, then that is the most optimal spot for your next mold outbreak. Some of the most common materials to get water damage or create mold growth-inducing conditions are wood, drywall, carpet, tile, HVAC, and wallpaper.
Mold on Wood
Some types of wood are more resistant to mold than others. If
wood is finished, it has a better chance of surviving a mold
infestation, because you should be able to wipe it up with
soap and water. Unfinished wood is extremely vulnerable
to mold growth, because the mold can easily burrow down
into its fibers and break down the material through the
secretion of chemicals. When this occurs on wood, it likely
This is particularly worrisome when that wood is important to the structural integrity of a home, such as on any kind of wood framing. If you see or suspect mold on wood in your house, it is in your best interest to act quickly.
Mold on Drywall
Drywall, also known as gypsum board, is another material that is very vulnerable
to damage resulting in replacement. It is typically made out of mineral gypsum
with thick paper layered on either side of it. Drywall can also come with a
variety of other coatings.
Just as with wood, mold is capable of burying itself into drywall and the only way to completely remove it is by tearing the wall out and replacing it.
However, this does not happen 100% of the time. If it is a light
mold growth, then you may just need a little soap and water to
remove the mold and of course change the conditions that
allowed for mold to grow in the first place.
Sometimes whether it is a light or significant mold growth
there could be the issue of additional mold growing behind
the drywall within the wall cavity. The way to test for this is to do
a wall sampling, which may require the drilling of a small hole in
the wall that has the contamination. To learn more about this, go
to our How to Test for Mold page. Besides seeing or smelling mold
in an area near drywall, other signs that a wall is water damaged and
vulnerable to mold growth include swelling or puckering of the drywall.
Mold on Carpet
Carpeting that has been around for a while can reveal the history of mold
growth in the room that it is located in. That is because with each mold growth
come markings on the underside of carpets. If a carpet becomes wet, it is
important to hang it so that it dries quickly (in under 48 hours). Do the same
with the carpet pad underneath it.
In some cases of mold growth, the mold may go through too much of the carpet and start to break down the material. This is when you will want to throw out the carpet and get a new one. Also if the water that caused the damage contaminated, like with sewage water for example, then you will want to throw it out as it will absorb and hold on to the harmful liquid.
Some places where it is unwise to have a carpeting put in include bathrooms, kitchens, uninsulated concrete floors, and some basements. This is because these areas are vulnerable to repeated moisture intrusion and if water can hide in the carpet without immediate drying, then mold growth will undoubtedly occur.
Carpet sampling is a method of determining if mold is growing in the carpeting. This entails inserting a cartridge deep into the carpet and using an air pump to vacuum up a small portion for sampling. More on this on our How to Test for Mold page.
Mold on Tile
Tile is a common place for mold growth since it is usually the main material in
areas like bathrooms and kitchens where there is a ton of moisture, which can
lead to frequent mold growth. What is great about tile is that if that is the only
spot where mold is growing it should be fairly easy to clean up. All you need
is a mild soap and water to wipe it up. Sometimes it can be just as easy if the
grout between the tile is affected as well, but in some cases grout replacement
may be needed depending on the severity.
Once you clean the mold, it is important to fix the moisture problem in the space. Make sure all pipes and fixtures are tightened so they do not leak and definitely ventilate the bathroom post-shower. You can do this by opening a window, running the fan, or bringing in a fan or dehumidifier.
Mold on HVAC
The heating, ventilation, and air-condition (HVAC) system is one of the scarier
places for mold to grow, because it transfers air throughout most rooms
of a building, thus spreading harmful spores. All that mold needs to
grow in an HVAC is a little dust or dirt to cling onto and then it just
waits for the moisture. Condensation is a common occurrence
in HVAC systems due to the different temperature air pockets
traveling on either side of its ductwork.
Mold removal in this area should be done by professionals with experience working on HVACs. To help ensure the safety of those inhabiting the building during mold remediation, the HVAC should be turned off and the intake and supply vents should be sealed with plastic and duct tape. This will help prevent the spreading of mold spores throughout the home that would put individuals at risk. For this reason, remediation of an HVAC system is better during hours when people are not around or needing air conditioning or heating.
Mold on Wallpaper
Behind wallpaper is a popular spot for hidden mold growth. If moisture finds
its way in through cracks in a wall, pipe leaks, or steam from a shower, mold
can start growing behind the wallpaper in these areas in as little as 24 hours.
It will start removing the stickiness of the wallpaper, causing it to pucker and
curl, as well as damage the drywall it is on.
Some other less obvious places to check for mold on wallpaper is in cold corners of walls and behind furniture. Once mold has made its way in, wallpaper replacement is likely necessary.
Other Places Where Mold Can Grow
Of course mold growth is not limited to just the surfaces listed above. Since mold only needs moisture and tiny dust or dirt particles to grow, the possibilities are virtually endless. Some other places to look include under vinyl flooring, above ceiling tiles, drain pans, behind items in storage, paint, fuel, glass, drapes, stainless steel, etc.