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If you own a home with wood siding in Covington, you already know that mildew is more than an occasional nuisance. Big Easy Siding works with homeowners across the Northshore who deal with mildew buildup every year, and the reason comes down to where Covington sits and how the climate works.
Covington and the broader St. Tammany Parish sit under one of the densest tree canopies in southeastern Louisiana. Live oaks, cypress, and pine create heavy shade that keeps moisture on exterior surfaces for longer stretches of the day. Combine that shade with Louisiana’s average relative humidity of 75 to 90 percent during the warmer months, and you have ideal conditions for mildew to take hold on wood siding.
Older homes on the Northshore are especially vulnerable. Many were built with natural wood clapboard or board siding that absorbs moisture more readily than modern composite materials. North-facing walls, areas beneath eaves, and sections of siding close to landscaping tend to develop mildew first because those surfaces stay damp the longest.
Before you start cleaning, it helps to know exactly what you are dealing with. Mold and mildew are both fungi that thrive in damp environments, but they look different and carry different risks.
Mildew typically appears as flat, powdery patches that are white, gray, or light brown. Mold tends to be darker, showing up as fuzzy or slimy spots that are green, black, or deep brown. On wood siding, mildew often looks like a light dusting or film, while mold can appear as raised, irregular patches that penetrate deeper into the wood grain.
Mildew is generally a surface-level issue and is not considered harmful to most people. Mold, on the other hand, can release spores that trigger respiratory problems, allergic reactions, and other health issues. If you see widespread dark discoloration or fuzzy growth on your siding, it is worth having the area tested before you begin cleaning.
Left untreated, mildew can lead to staining and surface degradation. Mold is more aggressive and can cause wood rot, weakening the structural integrity of your siding over time. In Covington’s humid climate, what starts as surface mildew can progress to mold if the underlying moisture problem is not addressed.
Gather everything before you begin so you can work through the process without interruption. Here is what you will need:
Follow these steps to safely remove mildew from your Covington home’s wood siding without causing damage to the wood itself.
Cover plants, shrubs, and flower beds near the siding with drop cloths or plastic sheeting. Cleaning solutions, even mild ones, can damage foliage if left in contact too long. Move outdoor furniture, grills, and decorations away from the work area.
Wear rubber gloves, safety goggles, and a dust mask. Scrubbing mildew can release spores into the air, and cleaning solutions can irritate skin and eyes. This is especially important if you are working on a section of siding where the growth has been building up over a full Louisiana summer.
Use a garden hose to rinse the affected area with clean water. This removes loose dirt, cobwebs, and debris so the cleaning solution can make direct contact with the mildew. Start at the top and work downward to avoid pushing dirty water into clean areas.
Using a pump sprayer or spray bottle, apply your cleaning solution to the mildewed sections. Work in manageable sections of roughly four to six feet at a time. Let the solution sit on the surface for 10 to 15 minutes so it can break down the mildew. Do not allow the solution to dry on the wood.
After the solution has had time to work, scrub the area with a soft-bristle brush. Use firm, even strokes that follow the grain of the wood. For stubborn deposits, reapply the cleaning solution and let it sit for another 10 minutes before scrubbing again. Avoid using metal brushes or abrasive pads, which can scratch and damage the wood surface.
Rinse the entire section with clean water from your garden hose. Make sure all cleaning solution residue is removed, as leftover product can discolor the wood or attract new dirt. Again, work from top to bottom.
Let the siding air dry before applying any sealer, stain, or paint. In Covington’s humid conditions, this may take one to two full days of dry weather. Do not seal or paint over damp wood, as trapped moisture will create the same mildew problem all over again.
The cleaning solution you use matters. Different options work better depending on the severity of the mildew and the condition of your wood siding.
Oxygen bleach is one of the safest and most effective options for wood siding. It breaks down into water and oxygen after use, making it gentler on plants and the environment compared to chlorine bleach. Mix according to the product label, typically one cup of powder per gallon of warm water. Oxygen bleach penetrates porous wood surfaces to kill mildew at the root, which helps prevent quick regrowth.
A solution of one part white vinegar to four parts water works well for light to moderate mildew. Vinegar is a natural acid that kills most mildew species on contact. It is safe for most painted and stained surfaces, though you should test a small, hidden area first. Vinegar is a good choice for homeowners who want to avoid chemical products.
A mixture of one cup chlorine bleach per gallon of water is effective for severe mildew. However, chlorine bleach can strip color from stained wood and may damage plants if it runs off into landscaping. If you use chlorine bleach, keep the affected area wet and rinse thoroughly after scrubbing. Cover all nearby vegetation before applying.
Several commercial products are formulated specifically for mildew removal on wood surfaces. Look for products labeled safe for wood siding and follow the manufacturer’s instructions for dilution and contact time. Many of these products contain surfactants that help the solution cling to vertical surfaces longer.
Pressure washing can speed up the mildew removal process, but it carries real risks when used on wood siding. High-pressure water can splinter wood fibers, force water behind the siding and into wall cavities, and strip paint or stain from the surface.
If you decide to use a pressure washer, follow these guidelines:
For older wood siding on Northshore homes, hand scrubbing with a cleaning solution and a garden hose rinse is usually the safer approach. If the mildew is widespread or the siding is in poor condition, a professional assessment can help you decide whether cleaning alone is enough or whether siding repair is needed.
Removing mildew is only half the job. In Covington’s climate, prevention is what keeps your wood siding looking clean between deep cleanings. Here are the most effective strategies for Northshore homeowners.
Overgrown vegetation traps moisture against the siding and blocks airflow. Trim tree branches so they are at least three feet from the exterior walls, and keep shrubs pruned so air can circulate freely around the base of your home. Given Covington’s dense tree canopy, this single step can make a noticeable difference.
Water pooling near the foundation splashes onto the lower courses of siding and keeps the wood wet. Make sure the ground slopes away from your home and that gutters and downspouts direct water at least four feet from the foundation.
After cleaning and drying your siding, apply a wood sealer or stain that contains mildewcide. These products create a protective barrier that resists moisture absorption and discourages fungal growth. Reapply every two to three years, or more frequently if your home sits in heavy shade.
An annual wash with a garden hose and a mild cleaning solution prevents mildew from gaining a foothold. The best time to clean siding in Covington is late fall or early spring, when humidity is lower and the siding can dry more quickly. For more guidance on routine maintenance, see our guide on how to clean wood siding.
Bird droppings, pollen, and leaf debris create a nutrient-rich surface that accelerates mildew growth. Remove these deposits as soon as you notice them. If birds are roosting near your siding, our guide on how to clean bird poop off wood siding covers the safest removal methods.
Sometimes mildew damage goes beyond what cleaning can fix. If you notice any of the following on your Covington home, it may be time to consider repair or replacement:
In these situations, replacing damaged sections or upgrading to a more moisture-resistant siding material is often more cost-effective than repeated cleaning. Our comparison of siding repair vs. replacement can help you weigh the options for your home.
Mildew on wood siding is a fact of life for Northshore homeowners, but it does not have to lead to costly damage. With the right cleaning approach and a consistent prevention routine, you can keep your siding in strong condition through every Louisiana summer.
Big Easy Siding works with homeowners in Covington and across St. Tammany Parish to clean, repair, and replace wood siding affected by mildew and moisture damage. Call us at (504) 766-3494 or request a free estimate online to schedule an assessment of your siding.
We serve New Orleans, Baton Rouge, Covington, Gretna, Hammond, Kenner, Metairie, Slidell, and throughout Louisiana.
Covington’s combination of high humidity, dense tree canopy, and warm temperatures creates ideal conditions for mildew growth. Wood siding absorbs moisture from the air and from rain, and shaded surfaces stay damp long enough for mildew spores to take hold and spread. North-facing walls and areas near landscaping are the most common starting points.
Chlorine bleach is effective against mildew but can strip color from stained wood and damage nearby plants. Oxygen bleach is a safer alternative that kills mildew without harming wood finishes or vegetation. If you use chlorine bleach, dilute it to one cup per gallon of water and rinse the surface thoroughly after scrubbing.
In Covington and across the Northshore, cleaning wood siding at least once a year is recommended. Homes in heavy shade or near dense vegetation may need cleaning twice a year. Late fall and early spring are the best times because humidity is lower and the siding can dry faster after washing.
Yes, pressure washing at high settings can splinter wood fibers, force water behind lap joints, and strip paint or stain. If you use a pressure washer on wood siding, keep the pressure below 1,500 PSI, use a wide-angle tip, and hold the wand at least 12 inches from the surface. Hand scrubbing with a soft-bristle brush is generally safer for older wood siding.
If the wood feels soft or spongy, if boards are warped or cracked, or if mildew returns within weeks of a thorough cleaning, the siding may have structural damage that cleaning cannot fix. In these cases, replacing damaged sections or upgrading to a more moisture-resistant material is usually the better investment for your Covington home.
By Admin 
Oct 21, 2022