Inspecting Your Roof Before Cleaning

Black streaks running down the shingles always catch my eye. Dirt? Nope, that’s algae. Weird structural stuff pops up all over—warped decking, popped nails, rusty flashing. People argue about cleaning methods, but nobody checks their roof’s material before blasting it with chemicals. Why is that? Shouldn’t we care more?

Spotting Signs of Moss and Algae Growth

Moss isn’t just ugly. Leave it, and it’ll pry up shingles, hold water, and rot what’s underneath. Homeowners swear the green fuzz wasn’t there last spring, but it’s always the shady, tree-lined roofs. Biology, not bad luck.

Algae—Gloeocapsa magma, if you want to get nerdy—leaves blue-black streaks, especially on asphalt. Greasy, stubborn, and regular rinsing won’t touch it. Bleach works, but it feels harsh. “Natural” removers flop in real life. The essential cleaning steps always start with just finding these signs. North and shaded faces? That’s where the party is.

Checking for Structural Damage

Step on a soft spot and tell me you don’t wince. Don’t stomp around hoping to find rot—start with your eyes, then your feet. Look for weird lines, broken tiles, daylight where it shouldn’t be, or water stains. Warped plywood? You’ve got bigger problems.

Loose shingles, especially near valleys or flashing, mean the wind’s been busy. I nudge them with my boot and make notes if something feels wrong. A quick inspection before you start scrubbing or spraying can save you from a collapse. No shortcuts—trust me, I’ve stood on enough sketchy roofs to know.

Identifying Roofing Materials

People keep asking, “Isn’t every roof just… a roof?” I wish. If you’ve ever tried to clean one, you know—nope. Asphalt, slate, clay, metal, composite—if you can’t tell them apart, you’re in for a bad time. Slate? Might as well be made of eggshells. Clay tiles? Soapy water turns them into a slip-n-slide. Metal? Every step sounds like a drum solo.

I never trust myself to start cleaning until I figure out what I’m standing on—seriously, try blasting old asphalt with a pressure washer and watch those granules bail out like rats off a ship. Even a gentle spray can snap ancient clay tiles. I’ll tap, poke, squint at profiles, and if granules flake off just from brushing, I’m not cleaning that roof, I’m calling someone about a replacement. The chemistry’s a mess—read a material compatibility warning or get ready for a surprise bill. Weird how much the details matter.

Choosing the Right Cleaning Method

I’ve lost count of the roofs I’ve watched get destroyed by people who just grab the first “powerful” thing they see—bleach on terracotta, pressure washers on soft shingles, you name it. Usually I’m watching from the ground, shaking my head. People think it’s about blasting off moss, but half the time they’re just stripping paint, voiding warranties, or launching moss spores into the neighbor’s yard.

Pressure Washing vs. Soft Washing

Pressure washing? Yeah, it’s fast. Like, “where did all the moss go” fast. Also, “where did half the shingle grit go” fast. I literally saw someone peel the top off an asphalt roof in twenty minutes with a 3500 PSI blaster. Still think that’s smart? I haven’t met a manufacturer who recommends it, and insurance adjusters just roll their eyes.

Metal, concrete, heavy-duty tiles (Monier, Boral, whatever)—maybe you can pressure wash those, but only if you’re watching every flashing and skylight like a hawk. Gutter lines? Forget it. Pressure finds every weak spot. Safety gear isn’t optional unless you enjoy ER visits. My rope access friend (he’s got, like, a million certifications) flat-out refuses to pressure wash tiles—he’d rather spend an hour soft washing than risk a fall. Wrong nozzle, wrong soap, bad angle—suddenly you’re chasing leaks for months. There’s a cleaning method comparison table buried in this guide—why do they always put the good info halfway down the page?

When to Use Gentle Approaches

Here’s the thing—soft washing is just less drama. Found this out on a slate job in Tasmania—low pressure (barely 100 PSI sometimes), biodegradable detergent, let it sit, rinse, done. No crumbling, no garden carnage. Everyone says, “Just use a hose!” but stubborn patches only disappear after a second chemical hit.

Personal favorite? Sodium hypochlorite mix (yeah, bleach, but diluted)—garden sprayer, gloves, check the wind. Bleach burns suck, and cloudy skylights are a pain. On clay or wood shakes, I barely touch the surface—too much pressure or the wrong mix and you’ll stain them forever. Loads of pros swear by soft wash for insurance reasons, too—some policies basically threaten you if you use abrasives. Fewer repairs, and, weirdly, gutters seem cleaner after? Not sure that’s real, but I’ll take it.

Veteran-Approved Roof Cleaning Solutions

Picture this: moss everywhere, me up a ladder (definitely not OSHA-approved), bucket in hand, staring at a shelf of “safe” roof cleaners and wondering if any of them won’t nuke the shingles or the neighbor’s cat. Sometimes I mix my own, sometimes I cave and buy a bottle—depends on the mood, honestly.

Homemade Roof Cleaning Solution Recipes

Bleach is still a thing, apparently, but every inspector I know gets twitchy when I bring it up. My mate in Manchester mixes 2 cups oxygen bleach, 1/4 cup mild detergent (eco powder, always), fills the rest of the sprayer with warm water, swears it’s magic.

Moss and algae? Give it thirty minutes, they’re gone—faster than getting my kid to do chores. Skip the detergent and mildew just hangs out for weeks. You have to rinse gently, not blast it off, unless you like leaks (see the warnings here). For stubborn patches, I’ll grab a soft brush. Vinegar? Don’t bother. Smells awful, kills nothing, ruins the drains.

Commercial Roof Cleaning Products

Commercial stuff? Half the labels say “eco-safe,” the rest look like chemical warfare. I spend more time reading ingredients than actually cleaning. “Oxygen-based,” “biodegradable”—if it doesn’t say that, I’m not buying it. Most roof inspectors (see UpClean’s breakdown) avoid harsh chemicals; pet-safe and plant-safe matter more than melting algae.

Soft wash detergents get my vote for new asphalt. Used a “SoftWash” product last fall (straight from Veterans Cleaning Solutions), cloudy day, no streaks, no drama. Pressure washers? Never again. Last time I tried, I ended up patching shingles and arguing about the ladder for hours.