Outdoor structures like redwood decks or redwood fences invariably get a little dirt on them from time to time. This is unavoidable. Thankfully, cleaning redwood is simple and easy. It’s also much easier to maintain than many other building materials. Please follow these tips and recommendations to help keep your project looking pristine for years to come.
For day-to-day, surface-level dirt, grime, and debris, all you need for cleaning redwood is a garden hose and a functioning spigot. Simply rinse off the affected area when you notice build-up. It’s as easy as that. Cleaning redwood really isn’t difficult, especially when you take a little time to periodically review the condition of your deck or fence.
In some situations dirt and grime may collect and build up on your redwood deck, fence, or garden structures. Sometimes, this may happen to the point at which a simple hose rinsing won’t quite do the trick. In situations such as these, the solution is often still quite simple. Get a stiff-bristled brush and a bucket of warm water mixed with a mild detergent, and scrub away at the affected area. This should clean up most caked-on dirt and grime.
Occasionally, mildew will build up on wood, especially in damper climates and where the wood surface remains out of direct sunlight. Mildew is identifiable as dark spots present on the wood surface. More severe cases can appear to be thickly black or gray. To treat milder instances of mildew build-up, simply treat the area as you would a caked-on area of grime, and scrub with warm water and mild detergent. Follow scrubbing by rinsing the affected area with household bleach, then with clean water.
For more severe cases of mildew growth, begin cleaning redwood by scrubbing the area with a stiff-bristled brush and a solution. The solution should include one cup of liquid household bleach and one cup of trisodium phosphate diluted in one gallon of warm water. Increase or reduce this amount as needed, but keep the proportions of the ingredients the same. Afterwards, rinse thoroughly. If needed, mix four ounces of oxalic acid crystals into each gallon of warm water. Use a non-metallic container and apply to the area with a gentle brush. After this solution dries, rinse the affected area with water.
Your best defense against mildew growth is the application of a water-repellent sealant that contains a mildewcide. For additional information about cleaning redwood and finishing it, visit our redwood finishing tips page. We also have information about how to go about refinishing redwood.