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Redwood Maintenance

Redwood is well known for its natural durability and easy maintenance properties.

Easy maintenance of redwood is possible when it comes to finishing your project. You may decide to choose the no-maintenance option and let your redwood deck or fence age naturally, taking on a soft, weathered look over time.

Conversely, you may decide to keep the surface color of your deck or fence looking like new with a finish that accentuates the unique characteristics of the wood. Redwood’s unique cell structure allows it to hold finishes better than other woods. Plus you can keep it looking like new by simply refinishing it every few years. In addition, redwood does not stain in the same way composite materials do. With redwood, you can worry less about barbeque grease, red wine or other spills on your deck.


As with any other outdoor building material, cleaning redwood is sometimes necessary. Fortunately, cleaning redwood is not difficult. Day-to-day, cleaning redwood is as easy as rinsing off your deck, fence, porch, or other outdoor structure with a garden hose. Clean water goes a long way towards keeping dirt and debris from building up on redwood. A more thorough cleaning may be accomplished by scrubbing the wood surface with a stiff bristle brush, a mild detergent and warm water. This method will generally remove built-up dirt and grime.

Sometimes, cleaning redwood is necessary when there is an occurrence of mildew on the surface of the wood. Mildew appears as dark or fan shaped spots on the wood surface. Particularly severe cases of mildew may result in an area appearing uniformly gray or black. Mild cases of mildew may be removed by scrubbing the surface of the wood with a mild detergent and water. The next step is to rinse the wood surface with regular household bleach. The final step is to rinse with clean water.

Cleaning redwood that has a severe occurrence of mildew requires scrubbing with a stiff bristle brush using a solution of one cup of trisodium phosphate (TSP), one cup of liquid household bleach and one gallon of warm water. Rinse thoroughly. If necessary, follow with an application of four ounces of oxalic acid crystals dissolved in one gallon of warm water in a non-metallic container. Apply evenly with a soft brush. When wood dries, rinse with water.


Redwood, like other natural woods, will eventually change color in the elements. Factors such as sunlight, moisture, and dirt contribute to natural discoloration. Luckily, color restoration of redwood decks, fences, porches, and shade structures is not difficult.

First, begin with identifying the cause of discoloration. Mildew, extractive bleeding and iron stain are common causes. Mildew usually appears as dark spots on redwood’s surface. Severe mildew may be uniform and cover a large area. You can test for mildew by applying a drop of household bleach to the dark spots. If mildew is present, the spots will disappear in one to two minutes.

The process of color restoration to the original redwood color of the wood begins with scrubbing the wood surface with a mild detergent to remove any mildew. Next, rinse the surface with household bleach. Finally, rinse with water. To remove severe mildew, use a stiff bristle brush and scrub the wood with a solution of one cup of trisodium phosphate (TSP), one cup of household bleach and one gallon of water.

Extractive bleeding is another cause of redwood discoloration. Redwood contains naturally occurring chemical extractives, which are water soluble. If these extractives reach the wood’s surface, they may cause dark staining. Redwood color restoration for extractive bleeding is accomplished using oxalic acid. Wash the redwood’s surface with one cup of TSP and one cup of household bleach mixed in a gallon of water. Rinse thoroughly and follow with an application of four ounces of oxalic acid crystals dissolved in one gallon of warm water in a non-metallic container. When the wood dries thoroughly, rinse with clean water.

Redwood exposed to iron and water causes the naturally-occurring tannins to react, forming dark staining. This can happen in any species of wood with high tannin content. Redwood color restoration for iron stain can be accomplished using the oxalic acid solution described above.


Redwood is nature’s own maintenance-free building material. When it comes time to build your Redwood project, easy to follow finishing tips are available to get you started.

Finishes formulated for wood surfaces that contain UV protection and a mildewcide offer the most protection for your redwood projects. Wood stains are generally available in clear, semi-transparent, and solid color options. Clear stains will allow the natural color and grain of the redwood to show through. Semi-transparent stains are available in a variety of attractive colors to customize the look at feel of the project. Solid color stains are opaque and hold up the longest, however they do obscure the natural grain and color of the wood itself. Painting redwood structures is certainly an option as well.

Regardless of the finish you choose, completing regular maintenance and keeping redwood structures clear of leaves and other debris will make refinishing redwood easy. The following finishing tips provide additional information:

  1. If the wood is unseasoned, allow it to be exposed to the ambient air for at least a month before applying any finish.
  2. Apply finishes on windless days. Ideal temperature is between 50 and 70 degrees (Fahrenheit).
  3. Redwood surfaces should be clean and dry.
  4. Thoroughly ventilate the area prior to finishing application. Moisture is a frequent cause of ineffective finishes, so be sure the proper precautions against it are taken. This includes using air vents, vapor barriers, and flashing.
  5. If your project is outdoors, choose wood finishes recommended for outdoor use only.
  6. Avoid using abrasive, metal-based brushes, since they may react with the wood and stain it. Choose stiff-bristled, non-metallic brushes.
  7. Be sure any products you mix are meant to be used together. Mixing dissimilar finishes might result in failure of the finish.
  8. Always follow the manufacturer’s specific instructions for all products used.
  9. Prime the wood prior to applying paints or other external finishes.
  10. Choose the finest hot-dipped galvanized nails available. Opting for lower-quality nails may result in stains. Alternately, opt for nails made from aluminum or stainless steel.
  11. Periodic rinsing with a garden hose will remove surface dirt and grime.
  12. Stubborn, built-up dirt and grime can be removed by scrubbing with a bristle brush and a solution of warm water and a mild detergent. Rinse afterward.


Redwood deck expert, Jeff Imwalle, walks through all the steps needed to refinish a redwood deck like a professional. Jeff’s expert guidance will help even the most inexperienced homeowners or do-it-yourselfers get started refinishing their redwood deck.