What is the Green Stuff on my Siding?

What Are Those Green Stains on Your Siding?

Rainfall in our area has been heavier than usual, and you may have noticed the results of that on your siding. Green spots and brown streaks on your siding can make your whole house look ugly and unkempt. Now that the sun is out, it's time to shed some light on what's causing those stains and how to clean them up. 

What Causes Green Spots on Siding?

 Most of us assume that a green stain on siding is mold or mildew. In fact, while these can cause green stains, there are more likely culprits. These include: 

  • Algae.

  • Lichens.

  • Moss.

  • Leak stains.

The good news is that all of these can be cleaned. You may have to wait until the weather starts warming up to find a sunny day.

Cleaning Algae, Lichens, Moss and Mildew

 1. Start by covering all outside light sockets and any outdoor plants that are close to the siding. Use plastic or cloth tarps.

2. Mix trisodium phosphate (TSP) and warm water in a bucket. This solution will clean almost all the green stains and kill the algae, moss and lichens.

3. If the stains don't come out, they are probably mold. Simply add oxygen bleach to the mixture. Oxygen bleach is a safe alternative to chlorine bleach that is just as effective at killing mold.

4. Use a sponge to wipe the mixture from the top of the wall to the bottom. As you finish scrubbing one section, hose it down with a power washer or garden hose.

5. Don't just spot-clean your siding. Wash the entire siding to get an even look. 

How to Clean Leak Stains

 If you notice red or brown streaks on your siding, they've probably been caused by water leaks behind your siding. This tends to be a problem in older homes. It's also common after periods of heavy rainfall or snow. Leftover rain and melted snow can accumulate and cause this problem. 

To clean it, use a power washer and the same TSP or oxygen bleach cleaning solution that you use for mildew, mold and other stains. Be careful to not let more water seep behind the siding. Make sure to spray from the top down to avoid getting water into the gaps between siding planks. Adding vapor barriers to your siding will help prevent this from happening in the future.

Get Your House Inspected Before Spring

 If you are battling mysterious green stains, leaks or other problems that are damaging your house, give Last Call Exteriors a call. If you don't feel like spending a cold day outside scrubbing your siding, we can take care of it for you. 

Last Call Exteriors can inspect, clean and repair: 

Get your house ready for spring with a total makeover that will let you enjoy warmer weather instead of worrying about your house. Call Last Call Exteriors today.

Request a Free Consultation