Removing Algae from Siding: A complete guide from Painters in Austin

How do you remove Algae from Siding?

Since it was first introduced in the late 1950's vinyl siding has gained popularity due to its versatility, strength, and ability to weather the elements. However, while the polymer material may be able to withstand high winds and harsh UV rays it is still susceptible to staining, including a green discoloration caused by algal bloom

Algae growth typically occurs in areas where dirt and dust have collected especially siding, as the organic material is used as a source of food. The algae may appear brown or green in color and remain damp, diminishing the appearance of your home and spreading out over time. Unlike mold, this type of growth is mainly cosmetic and can be removed using minimal force and a few basic materials. We at Painters in Austin are here to help you spruce up your home this summer with our comprehensive guide on how to remove algae from your home. Keep reading to find out more!

So what exactly is algae and what causes algal bloom?

There are several different types of Algae. However, a microorganism often referred to as “blue-green algae” is actually a type of harmful bacteria called, cyanobacteria.
Cyanobacteria are inconspicuous year-round inhabitants of freshwater bodies; only making themselves known when they undergo a growth spurt of an abnormal population.
This growth spurt is called a bloom; A bloom of Cyanobacteria produces the visible green “algae” residue that appears on the side of homes.

The factors leading to a bloom are believed to include: exposure to sunlight, warm temperatures, cloudy water; and an enriched supply of nutrients, such as phosphorus and nitrogen. Too much nitrogen and phosphorus allow bacteria to grow quicker than ecosystems can handle

How do I know if my siding has algae and mildew on it? Look for stains. Stains are the most common sign that you have algae or mildew. The stains can be different colors, which can often tell you what is causing the growth.

  • Brown stains on wood siding can signal that moisture is forming underneath the wood.
  • Black stains are usually a sign of mildew, algae, mold or fungus.
  • Green stains are almost always the result of algae or moss. You’re most likely to see green stains on siding that is inadequately ventilated.
  • Yellow stains mean you probably have damaged insulation or deteriorating sheathing behind the siding.
  • Stains the same color as your siding are typically caused by water streaming down siding due to damaged or misaligned gutters. These leaks can get behind your siding and eventually cause mildew or mold.
  • Rust-colored stains are usually a sign that nails in the siding are rusting. This may or may not mean you have excess moisture leading to mildew.

How to Remove Algae From Siding

  1. Gather your materials.
  • Duct tape
  • Plastic sheeting
  • Large bucket
  • Garden hose with a spray attachment or power washer
  • Oxygen bleach
  • Long-handled scrub brush
  • Water resistant footwear and gloves

2. Protect your exterior

Protect vulnerable entry points on your home’s exterior such as electrical outlets, exhaust vents, and more by covering them or taping them closed with duct tape. Use plastic sheeting over top of plants and landscaping that are in close proximity to the home, and ensure all doors and windows are closed.

3. Mix your cleaning solution:

Fill a bucket with warm water and mix in the oxygen bleach powder (the Painters in Austin recommendation) according to the package directions.

4. Test a small area:

Dip the scrub brush into the solution and test it to see if it is effective at removing the staining. If not, the green discoloration may be mold.

5. Apply some elbow grease:

Begin at the top of the house and work your way down, dipping the scrub brush into the mixture and applying force with a side to side motion. Divide the project into manageable, 20-foot sections, rinsing each one well from the top down once completed.

6. The Pools:

Blue or green algae is the most common strain of pool algae, but it is no less difficult to clean. Green algae clings to the walls of your pool, but can also be free floating which creates murky, swamp-like film over the water. You guessed it – you’ll need the good old scrub brush and some borax. 

In the same way that baking soda can be a spot treatment for black algae, household borax does the same for blue and green algae. Simply use the borax to scrub away algae that’s sticking to your pool walls, then use the brush to dislodge it. Follow up by vacuuming up or scooping out the free-floating algae. You will have a much easier time once the borax has stopped the algae from blooming.

Call Painters at Austin today to get started with finding the perfect paint finish for the exterior and interior of your home. Get a free quote for any of our services- and sit back to watch the magic happen