Why Your New Bern Siding Turns Green (and How to Keep It From Coming Back)

That green on your siding is algae, and it's growing there because New Bern gives it everything it needs. Washing it off is easy. Keeping it off is the part most people get wrong.

I wash houses all over Craven County, and this is the single most common call I get. Somebody finally notices the side of their house, usually after a neighbor gets theirs done, and they want to know what it is and whether it's going to ruin their siding.

Here's the straight answer.

It's alive, and that's the whole problem

The green is algae. The black spots and the gray film mixed in with it are mildew and mold. All three are living organisms, not dirt.

That distinction matters more than it sounds like it should. Dirt sits on a surface and comes off when you knock it loose. Algae grows into the surface, feeds, and reproduces. If you knock it loose without killing it, it comes back faster than it did the first time, because you left the roots behind and gave it a clean surface to spread on.

That's why the guy who borrows a pressure washer from his brother-in-law is back out there again in four months.

Why New Bern is so hard on siding

We sit right where the Neuse and the Trent meet. Between the rivers, the humidity, and our rainfall, the air here holds moisture most of the year. Algae needs moisture, shade, and a surface to hold onto. We hand it all three.

The things that make it worse on a specific house:

North and shaded sides. This is the big one. The north side gets the least sun and stays damp the longest. On most houses I wash, the north side is green and the south side still looks decent. Homeowners are always surprised, because they pull into the driveway on the good side every single day and never walk around back.

Tree cover. Beautiful lot, shaded yard, and a permanently damp wall. Big oaks and pines mean more shade, more debris, and more moisture holding against the house.

Sprinklers hitting the wall. Check where your irrigation heads are actually spraying. A head that throws water on the siding every other morning is running a greenhouse on the side of your house.

Gutters and downspouts. A clogged gutter or a leaking seam keeps one section of wall wet all the time. You'll usually see a dark streak straight down from the problem.

Being close to the water. Salt air and film build up faster the closer you are.

Will it actually damage the siding?

Given enough time, yes.

Algae and mildew hold moisture against the surface. On vinyl, that means it works into the texture and gets harder to remove every year you leave it. On painted wood and trim, the moisture works under the paint and you start losing the finish. On wood that's already bare or has failed caulk nearby, you're looking at rot.

None of that happens in one season. But I've washed houses that went five or six years untouched, and the difference between those and a house washed regularly is real. The neglected one takes two applications and still doesn't come back all the way, because the growth was there long enough to stain.

The cheap version of this problem is handling it every year. The expensive version is replacing siding.

Why pressure is the wrong tool

Do not blast your vinyl siding.

High pressure forces water up behind the panels. It gets in, it doesn't come out, and you've traded a green wall for a moisture problem inside it that you won't find out about for a couple of years. The vinyl siding industry's own maintenance guidance says to hold the spray straight at the siding at eye level and never aim the stream upward under the laps.

The right approach is soft washing. Low pressure, a mild cleaning solution, and enough dwell time to let the chemistry actually kill the growth. Then a thorough rinse.

Soft washing gets a better result than pressure because it kills what's growing instead of stripping the top layer off. It stays clean longer for the same reason.

Why we soak your plants

Every side of your house, we soak the beds with clean water before anything gets applied, re-wet them if the side is taking a while, and flush them again after.

A plant that's already full of water can't take up much of anything else. A dry one drinks whatever lands on it. That's the whole trick, and it's the step every rushed crew skips because it's the step nobody watching can tell you skipped. You find out three weeks later when the azaleas start dropping leaves.

Around here it's azaleas, camellias, and hydrangeas on nearly every job. They're shallow rooted and they show damage first. We treat every bed like it's the prize planting, because usually it is.

If you're getting quotes and nobody mentions your landscaping, that tells you something about how they work.

How to keep it from coming back

You can't stop algae from existing in New Bern. Spores are in the air. What you can do is take away the conditions that let it take hold, and reset the clock before it gets established.

A few things that help:

• Aim irrigation heads away from the house

• Keep gutters clear so no section of wall stays wet

• Trim back shrubs and limbs that press against the siding or keep it shaded

• Fix the leaking gutter seam that's leaving the streak

And then wash it on a schedule instead of waiting until it's bad.

That last one is the real answer, and it's why we put together the Perfectly Clean™ Plan. It's a recurring plan where we come out on a set schedule and keep the house maintained instead of you calling us when you finally can't stand looking at it anymore. You don't think about it, you don't schedule it, and your house never gets to the point where it needs the hard version of the wash.

Washing a maintained house is faster and easier than rescuing a neglected one. That's the whole idea.

Common questions

How often should I have my house washed in New Bern?

Most homes here do well on once a year. Heavily shaded lots, homes under big trees, or houses close to the water usually want it more often than that.

Can I just use bleach from the store and a garden sprayer?

You can, and people do. Two problems. Household bleach is much weaker than what we use, so you'll get a poor result, and it has additives in it. The bigger issue is your landscaping. Applying any of this without properly soaking and flushing the beds is how people kill a row of shrubs they've had for fifteen years.

Will the green come back?

Eventually, yes. It's biological and the spores are in the air here. A proper soft wash kills what's on the wall and keeps it clear for a good while, usually 12 to 18 months depending on the house and how shaded it is.

What about the black streaks on my roof?

Different organism, same idea. That's roof algae, it's common all over eastern NC, and it also needs a soft wash and not pressure. Ask me about it when I'm out there.

My house doesn't look that bad. Is it worth doing?

Walk around to the north side and the back before you decide. That's usually where the conversation starts.

Getting a quote

Text me the address and I can usually get you a number the same day. If you want me to walk the property with you, I'm happy to come out and look at it.

Michael Reynolds

Pro Wash Pressure Washing LLC

Veteran owned, New Bern, NC