Why is My Cedar Siding Turning Black?

Homeowners often notice that their cedar siding begins to turn black over time. This can be both frustrating and concerning, as it affects the overall appearance and curb appeal of their homes.

There are a few common reasons for this discoloration, and understanding them can help you prevent further darkening and restore the natural beauty of your cedar siding.

One of the primary causes of blackened cedar siding is the presence of tannin stains. Tannins are natural substances found within cedar wood, serving to protect the living tree.

However, when the wood is used as siding, these tannins can leach out and oxidize, causing unsightly darkening. Another common reason for blackening is the growth of mildew or mold on the wood's surface.

This typically occurs when the cedar siding is exposed to excessive moisture or in areas with high humidity.

By identifying and addressing the root causes of blackened cedar, homeowners can effectively restore the aesthetic appeal of their homes.

Proper cleaning, treatment, and ongoing maintenance can stave off the dreaded discoloration and ensure that cedar siding remains a beautiful and durable exterior.

Understanding Cedar Discoloration

cedar sided house with red door

Cedar siding is widely admired for its aesthetic and durable qualities. However, over time, it can undergo noticeable discoloration.

Understanding the reasons behind this change can empower homeowners to maintain the cedar siding's appearance.

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Effect of Moisture

Moisture plays a significant role in the discoloration process of cedar siding. When cedar wood becomes damp, it creates an ideal environment for various organisms to settle and grow.

Over time, this moisture-driven change modifies the cedar's appearance. Due to its porous nature, cedar tends to absorb water more rapidly compared to many other wood types.

Hence, it's essential for cedar siding to be effectively sealed and consistently maintained to guard against discoloration stemming from moisture.

Impact of Sunlight

Exterior of a very large craftsman style home with cedar siding grand entry porch with stones and stairs also patio planters with green foliage

Sunlight is another factor that contributes to the blackening of cedar siding. Prolonged exposure to UV rays breaks down the wood fibers and natural oils, causing them to lose their natural color.

This, in turn, makes the cedar more prone to developing a rough, dark appearance.

Proper maintenance, including regular staining and sealing, can help protect cedar siding from the harmful effects of UV rays.

Role of Mold and Mildew

Mold and mildew are common culprits behind the blackening of cedar siding. These microorganisms thrive in moist, damp conditions, making cedar a perfect breeding ground.

Cedar can also develop tannin stains when tannins mix with metal and iron, causing a chemical reaction that results in black stains.

Be sure to read: How To Replace Siding On A House [Step By Step Guide]

Causes of Blackening

An external cedar wood wall turning black with a closed blue trim glass window. The walls are textured with brown and tan colored shades on the wood. The shakes are in lines and layers on a shed or wall.

Cedar siding is known for being both beautiful and durable, but it can lose its charm and turn black due to various reasons. Knowing these reasons is essential to keep your cedar siding looking good and strong.

Inadequate Maintenance

Cedar siding can turn black due to inadequate maintenance, which leads to the accumulation of dirt, grime, and organic material over time.

Regularly clean the siding using a gentle cleaner and soft brush, to remove debris and prevent buildup. A safe deep-cleaner for wood siding is oxygen bleach.

Annual inspections and timely repairs can help maintain the beauty and durability of cedar siding.

Poor Installation

Cedar siding with a red window frame

Improper installation of cedar siding can cause premature blackening.

If the siding is not installed correctly, moisture can become trapped between the siding and the underlying structure, leading to mold and mildew growth.

Proper spacing, flashing, and moisture barriers are crucial during installation, to prevent the formation of black stains caused by tannins reacting with metal and iron.

Environmental Factors

Front of rental cabin with cedar plank siding

Environmental factors such as humidity, precipitation, and exposure to sunlight can contribute to the blackening of cedar siding.

Areas with high humidity levels are prone to mildew and mold growth, which appear as black stains on the cedar siding.

Frequent exposure to sunlight can also cause the natural tannins in the wood to leach, leading to dark spots.

To prevent cedar siding from turning black, homeowners should consider using a high-quality stain or paint to protect the wood from excess moisture and sunlight.

Prevention Strategies

To keep your cedar siding looking its best and avoid blackening, consider these strategies:

Proper Installation

Proper cedar siding installation is crucial in preventing it from turning black.

Ensuring good craftsmanship and following the manufacturer's guidelines can help maintain the natural color of cedar siding.

This includes using appropriate nails, leaving enough space between planks for ventilation, and applying water-repellent preservatives before installation.

Regular Cleaning

Craftsman home cedar siding solid wood pillars patio veranda deck grassy green yard blue sky and landscaping

Regular cleaning is essential in maintaining the appearance of cedar siding. Dirt and other debris can accumulate over time, creating an environment for mildew and mold growth, which can cause the cedar to turn black.

To keep the cedar clean, use a gentle wood cleaning product and follow the directions on the container.

For cases with mildew, a solution of one part household bleach to nine parts water can be applied to the siding.

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Selective Shading

Providing selective shading for cedar siding can help prevent it from turning black due to constant sun exposure.

Ultraviolet (UV) rays from the sun can cause the wood to fade, while excess moisture can encourage mold and mildew growth.

Applying a stain that blocks ultraviolet light and contains a mildewcide can protect the cedar siding from turning black.

In addition, using landscaping or architectural elements like pergolas, trees, or awnings to provide shade can further reduce the risk of discoloration.

Treatment Options

Man cleaning cedar shingles

When dealing with cedar siding turning black, there are different treatment options. These include professional cleaning, siding replacement, and DIY cleaning methods.

Professional Cleaning

Hiring a professional cleaning service can ensure your cedar siding is treated effectively and safely.

These professionals have the knowledge and equipment to remove blackening caused by mildew, mold, and tannins without damaging the wood.

A thorough cleaning can help restore the natural beauty of your cedar siding and prolong its lifespan.

Siding Replacement

Cedar shingles which have shrunk and faded gray with age in the early morning light.

Sometimes, the cedar siding may be too damaged or deteriorated to be effectively cleaned. If this is the case, it may be necessary to consider a siding replacement.

Professionals can help you assess the condition of your cedar siding and determine if it's time to replace it. Remember that properly maintained cedar siding can last between 20 to 40 years.

DIY Cleaning Methods

Old wooden house cedar siding

If you prefer to handle the cleaning process on your own, there are some DIY methods you can try.

One option is to use a wood cleaning product to remove surface dirt before addressing the black spots caused by mold or mildew.

Another approach involves using a solution of one part household bleach to nine parts water to treat mildew.

Apply the bleach solution to the siding using a brush or roller, then scrub with a nylon brush and rinse. This should clear up mildew almost immediately.

Proper cleaning and maintenance routines, such as periodic pressure washing, can help prevent its growth on the cedar siding.

If the blackening is caused by tannin, applying a wood brightening solution and then rinsing with water after 30 to 45 minutes can effectively restore the cedar's appearance.

Remember to be careful when working with cedar siding, as improper cleaning techniques can damage the wood further.

In Closing

Craftsman home cedar siding solid wood pillars patio veranda deck grassy green yard blue sky and landscaping

Cedar siding is a popular choice for many homeowners due to its natural beauty and durability. However, over time, it may start turning black.

This is mainly caused by different factors: tannin stains, excess moisture, sunlight, and mildew growth.

Understanding these issues can help homeowners take the necessary steps to restore and maintain the original appearance of their cedar siding.

Proper identification and appropriate treatment can help preserve the beauty and longevity of this attractive and durable wood siding material.

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