Awful Algae: The Bane to Vinyl Siding And How To Defeat It

One of the reasons why homeowners opt for vinyl siding instead of wood siding is because vinyl siding is supposed to be cost effective and relatively maintenance free. If you chose vinyl siding for these reasons, you are probably dismayed to discover a green film of algae creeping over your home's exterior finish. Is it harmful? What causes the growth and what can you do about it?

What causes algae growth on vinyl siding?

Algae can never grow without a food source. Green growth on your siding happens because your siding is not clean. Algae feeds especially well on sugar. If you have a lot of trees on your lot, or if you have an abundance of woody plants, these plants will leave a slight film of sugar deposits on your siding over time, especially during spring when pollen and sap are running. Algae begins to feed on the sugar, and areas that receive little sun and have plenty of moisture promote even more excessive growth. Other food sources include dirt and dust, which will have carbon-based particles that algae can digest, particularly if you live in a rural area with plenty of farms. High humidity levels will also lead to algae growth. 

Will algae harm your siding?

Fortunately, algae on vinyl siding will not affect the function of your siding or cause it decompose. However, if the algae is left to flourish, it could permanently stain lighter-colored siding with unsightly green, brown or black spots. To prevent stains, you will need to clean your siding thoroughly to kill the algae and prevent it from returning.

How can you clean the algae so that it will not return?

You might be tempted to tackle the algae with a pressure washer or high-powered nozzle on your garden hose. These will work in temporarily removing surface greenery, but they can actually damage your exterior by allowing water to get underneath your protective siding, leading to water damage and mold growth. Instead, it is better to:

  1. Mix a cleaning solution. Some effective cleaners include oxygen bleach or trisodium phosphate. A small amount mixed with water will be the most effective. Try to stay away from using household detergents, car wash soaps, or chlorine bleach, as these can leave films on your siding or cause permanent discoloration.
  2. Use a bristle brush attached to a long pole to apply the solution to your siding, scrubbing hard to get the surface algae off. 
  3. Rinse the first solution and the algae using a garden hose with a simple spray nozzle. If you have plants that will be in the path of the falling rinse water, cover them to protect them from being poisoned by the cleaning solution.
  4. Reapply the cleaning solution with the scrub brush and work over all affected areas again. This will kill any remaining algae and help to prevent regrowth.
  5. Rinse thoroughly. If possible, run a microfiber cloth over the area to pick up remaining water and left over spores. 

Even after a thorough cleaning, you might be discouraged to see algae return in a year or two. This is because the bleach has worn off and the sugars have re-coated your siding. You can easily prevent the recurrence by giving your siding a once-over with similar, but more mild, cleaning solution made from oxygen bleach each spring. 

Algae growth can make even the most beautiful vinyl siding appear stained, ruining your home's curb appeal. With proper cleaning, you should be able to defeat the green growth once and for all. If discoloration or algae growth persists, you will need to contact a siding contractor to discuss other options or more intensive cleaning methods. 

For more tips, contact a company like Lifetime Exteriors.

Share