How to Get Rid of Algae on Wooden Stairs

Green algae growth on wooden stairs is usually an outdoor problem that occurs on places where water collects and forms a continuous wet area or on wood that has been exposed to the elements for a long time and lost the protection of paint or stain.

Removing the Algae

When algae growth does occur on wooden stairs, the problem needs to be dealt with right away as the problem will only get worse over time.

Begin algae removal by scraping all affected areas of wood with a stiff putty knife or paint scraper. Much care should be taken so as not to gouge or mar the wood. A high-powered pressure washer is not recommended because it may damage wooden stairs. When you begin the scraping process, keep in mind that the idea of the first step is not to remove all the algae growth, just the areas where the algae has built up excessively. This hand scraping process also allows you to closely examine the extent of algae growth on your stairs.

Continue the algae removal process by scrubbing with coarse steel wool and a mixture of warm water and a mild biodegradable soap and detergent. Use some elbow grease and scrub hard until the algae is completely removed. If large areas of growth are present, a long-handled, plastic scrub brush might be helpful.

Rinse the stairs with clean water.

Clean the wooden area with a long-handled scrub brush and a mixture of warm water and an oxygen bleach cleaner. Clean all areas of the wooden stairs completely. Be sure the cross-cut sides of the wooden steps are treated with the oxygen bleach mixture as well as the main surface of the treads and risers (if present).

Rinse the stairs with a garden hose (if outdoors) or a pail of clear water and a sponge.

Let stairs dry thoroughly, then seal, paint or stain them to help prevent the algae from returning.

Things You Will Need

  • Putty knife
  • Paint scraper
  • Coarse steel wool
  • Biodegradable liquid soap
  • Plastic bucket
  • Long-handled scrub brush
  • Large sponge
  • Oxygen chlorine bleach
  • Wood sealer or stain


  • Algae problems can also develop indoors, especially in places like basements where moisture levels can become very high.
  • Designing outdoor stairs that shed rainwater and snow buildup will go a long way toward preventing algae growth. Take note of potential trouble spots such as balusters, where water can collect and remain present for a long time.
  • Paint or stain your stairs on a regular basis to prevent algae invasion.


  • Use oxygen bleach cleaner instead of chlorinated bleach, as it is less harmful to the wood and surrounding plant life.

About the Author

Henri Bauholz is a professional writer covering a variety of topics, including hiking, camping, foreign travel and nature. He has written travel articles for several online publications and his travels have taken him all over the world, from Mexico to Latin America and across the Atlantic to Europe.