Mold and Mildew on Exterior Walls: Why It Happens in Florida and What to Do
If you are a homeowner and live in Port Saint Lucie, you have no doubt had this experience before.
You are walking up the driveway and everything looks normal until you see a
black spot near the bottom of the wall, or a green streak under the window, or
one side of the house always appears dirty despite how many rinses it can get.
It is frustrating because it could ruin the appearance of a well kept home.
That is the nature of Florida, mold and mildew do not always wait for your home to be abandoned before they move in.
The combination of warm air, moisture, shade, rain, landscaping, and the humidity that keeps the outside of your house damp for long periods of time.
So if you are seeing repeated issues of mildew on your exterior walls, it does not
mean that you are necessarily failing as a homeowner.
It simply means that the surface is holding moisture and the paint, wall, or
surrounding area could stand to be a little refreshed.
Quick answer
Mold and mildew grow on the outside of our homes in Port Saint Lucie because
of the dampness that is held on the surface.
Rainy season, humidity, shade, overspray from sprinklers, clogged gutters, and
landscaping can all conspire to keep a home damp and prone to repeated stains.
These stains are a nuisance, but cleaning alone is not always the solution.
The source of the moisture should be addressed as well.
The EPA has a great deal of information on moisture and mold, as well as the
methods of controlling both.
They recommend that mold control be focused on moisture control as simply
cleaning can lead to recurring issues if the source of the water is not removed,
you can read more from the EPA mold and moisture guide.
The proper method for a Port Saint Lucie home would consist of a safe wash,
improved airflow around the areas in question, moisture control methods,
structural repairs, and repainting when the existing coating is no longer
providing the needed protection.
Why it happens so often in Port Saint Lucie
Florida takes its share of abuse.
High temperatures, humidity, afternoon rainshowers, shady spots that the sun
cannot reach to dry walls, overspray from sprinklers, and the moisture retaining
properties of the landscaping can all contribute to mildew issues occurring.
These stains tend to develop in the same spot.
It could be the side of the home that gets the least amount of sun, under a bush,
along the soffits, or at the base of the stucco walls.
It could be wherever the sprinklers are set to hit every morning.
A homeowner might get it cleaned, think nothing of it, and a month or two later,
it is right back there.
That is an indicator that the wall is constantly damp.
Mildew is not just a dirty wall problem
That's the thing about this, it is a pre paint inspection issue.
A dirty wall can be cleaned, but a moisture pattern has to be corrected.
If the same stains keep coming back in a specific location, asking why it happens
is better than asking how to remove it.
Sometimes it is a very simple solution, a branch from a nearby bush is brushing
against the wall and retaining moisture there, a gutter is overflowing and soaking
the home's siding, or the sprinklers need to be adjusted so they are not hitting
the house.
Other times, the paint is simply worn down enough that the wall cannot properly
shed the moisture and mildew has an easy place to grow.
Why not to paint over the mildew
Painting over the mildew is an easy temptation that seems like a good idea at the
time, but it is one of those jobs where people wish they hadn't done it in the five
minutes following the completion.
The wall is dirty, so paint it over and be done with it.
The problem with this line of thinking is that paint needs a nice, clean, dry surface
to adhere to.
By painting over the mildew, you are painting over growth, dirt, and moisture
residue that will eventually cause the stain to come back, poor adhesion, and a
paint job that doesn't last as long as it should.
Before any exterior painting is completed, mildew needs to be cleaned and
treated before the new coating is applied.
The wall needs to be dried and any cracks, failed caulk, or weak spots need to be
repaired before applying a new layer of paint.
For those looking to repaint, that is where Exterior Painting Service fits in
perfectly.
The small things that cause the problem
Most issues are not mysterious, one or two simple things around the property are
the cause of the problem.
Sprinklers hitting the wall
One of the biggest contributors to mold and mildew in Port Saint Lucie is the
sprinklers that hit the same stucco wall every morning, keeping the surface
damp for an extended period of time.
Close plants
Shrubs and branches can hold moisture against the wall and reduce the amount
of airflow reaching the surface.
Overflowing gutters
Clogged or overflowing gutters run down the side of the home and soak the
paint.
The EPA recommends keeping gutters clean and repaired as a part of moisture
control, that same practice also aids in the preservation of exterior paint.
Shaded walls
Some walls receive very little sun exposure and tend to remain damp for long
periods of time.
Old paint protection
As paint ages and fades, the protective quality of the surface is reduced which
allows for dirt and moisture to cling to the surface and encourage growth to
occur.
What should happen before repainting
A proper repaint should not simply be opening a can of paint and getting to work.
The surface should be inspected before any paint is applied.
A proper prep consists of the following steps.
Walk around the home and identify areas of repeated staining
Determine the source of the extra moisture
Wash the exterior safely
Treat any areas of mildew or algae
Allow the wall to completely dry
Address cracks, peeling paint, and weakened caulk
Prime problem areas when needed
Apply the appropriate exterior coating
This is the proper prep for a lasting paint job, it is a standard procedure.
If someone is looking for a more full service prep and paint, send them to Services.
Does mildew resistant paint help
It can, but it is not a complete solution.
Mildew resistant paint works best when the wall is clean and the source of the
moisture has been addressed.
If the sprinklers keep hitting the same spot every morning or the shrubs are
holding moisture against the wall, mildew resistant paint is simply being asked to
do too much.
It is a part of the plan, but the wall still needs airflow, cleaning, and proper
drainage.
What a homeowner can do in between paint jobs
It does not mean waiting until the house needs a complete repaint to address
issues, a few simple maintenance tasks can prolong the life of any exterior paint
job.
Wash the exterior once or twice a year
Trim plants that get too close to the wall
Adjust sprinklers so they don't hit the house directly
Clean gutters before the rainy season gets going
Touch up peeling paint as soon as possible
Check caulked areas
Inspect shaded walls after storms
These simple maintenance tips will prolong the life of any exterior paint job and
ensure that the home looks nice in between repaints.
When mildew means repaint
Mildew alone does not always indicate that a home needs a complete repaint,
but if it is combined with other issues, it could mean that the paint is worn down
and the surface needs to be refreshed.
Chalky walls, peeling and bubbling paint, failing caulk, fading stucco, repeated
staining, and cracks that retain moisture are all issues that may require an
exterior repaint.
At this point, simply cleaning the surface can only provide a small reprieve before
the next set of stains occur.
For assistance inspecting the condition of the paint, homeowners can start with
FAQs
Why does mildew keep coming back on my exterior walls
Mildew tends to recur when the surface remains damp, shade, sprinklers,
clogged gutters, heavy landscaping, and worn paint can all contribute to this
issue persisting.
Can I paint over mildew
No, mildew should always be cleaned and treated before new paint is applied.
Paint requires a clean and dry surface to properly adhere and provide the
longevity that is expected from any exterior paint job.
How do I help prevent mildew on stucco
Keep plants trimmed away from the wall, adjust sprinklers, clean the exterior
regularly, repair cracks, and repaint when the old coating is failing.
Does mildew resistant paint stop mildew completely
No paint can stop mildew from growing if the surface is constantly wet, mildew
resistant paint helps in most cases when the surface is properly cleaned and the
moisture issue is resolved.
What should I do first if mildew keeps coming back
Address the source of the moisture.
The EPA has a lot of information on mold and moisture, they recommend that
moisture control is vital in mold control.
If you simply clean the surface and do not address the water source, it will most
likely happen again, more information can be found from the EPA mold and
Closing thought
Mold and mildew on exterior walls are a common nuisance in Port Saint Lucie, a
sign that the surface has been retaining moisture for too long.
Sometimes the issue is simple, trim the shrubs, adjust the sprinklers, clean the
gutters, or wash the wall more often.
Other times, the paint has worn down to the point that a complete repaint is the
only solution.
The best course of action consists of cleaning the wall, addressing the source of
the moisture, repairing any weak spots, and repainting when the old coating is
no longer doing its job.
This ensures that there is no endless chase of the same stains, but rather a nice
clean repaint that lasts for years in the climate of Florida.
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