A streaky, dark roof does more than drag down curb appeal; it can shorten shingle life and feed moss that holds moisture against the decking. Most homeowners tackle it once, then quietly hope the rain will do the rest. The right cleaning product makes that first pass actually count, whether you’re fighting algae bloom on asphalt shingles, soot near a chimney, or tar splatter from a recent roof repair.
The Choices Worth Comparing
Savogran 10621 Trisodium Phosphate (TSP) 1LB Pack of 2
RMR-86 Pro Contractor Grade Mold Stain Remover, 1 Gallon
30 Seconds 2.5G30S Biodegradable Outdoor Cleaner, 2.5 gal
Trick Shot Asphalt Solvent and Cleaner, 16 Fl Oz
A Breakdown Of The Leading Choices
Trisodium phosphate, or TSP, is the powder painters have trusted for decades when a surface needs to come truly clean before coating. You mix it with warm water, scrub it onto chalky, soot-stained, or grimy areas, and rinse it off before it dries on the surface.
For roof work, that matters when you’re prepping for a coating or cleaning after a paint-stripping job. The two-pound total gives you enough headroom for a small gable or a single shed roof without running out mid-rinse.
The Case For It
- Trusted by painting professionals for decades on tough prep work.
- Powder format stretches a small box across a large surface once diluted.
- Clears soot and chalky residue that milder soaps leave behind.
- Pack of two means you can finish a full roof pass and keep some in reserve.
Things To Consider
- It’s not a “spray and walk away” algae killer; expect real elbow grease.
- Rinsing thoroughly matters, since residue can interfere with new coatings.
- Stronger than dish soap, so gloves and eye protection are wise.
At A Glance
Made For
Homeowners prepping a roof for paint or sealant, and anyone who wants a serious, classic prep cleaner rather than a gentle surfactant.
Look Elsewhere When
Your main enemy is black algae streaks, in which case RMR-86 Pro Contractor Grade Mold Stain Remover is built for that fight.
Those black streaks running down asphalt shingles are usually Gloeocapsa magma, a hardy algae that feeds on limestone filler. RMR-86 Pro Contractor Grade is formulated specifically to break those stains down fast on exterior surfaces.
The one-gallon jug suits larger roof faces and the surrounding trim, and its deep-penetrating formula is what contractors reach for when milder outdoor cleaners come up short. Compared to the powder prep approach of Savogran 10621 Trisodium Phosphate, this one is more about stain removal than surface prep.
Practical Advantages
- Targets mold and mildew stains, the dark streaking most roofs actually show.
- Contractor-grade strength means fewer repeat applications on stubborn patches.
- One gallon covers a meaningful share of a typical suburban roof.
- Works on siding and trim too, so you can treat the whole exterior in one pass.
Worth Noting
- Wet roof surfaces get slippery, so plan for proper footing and a safety line.
- Strong chemistry means nearby landscaping should be pre-wet and rinsed after.
- Coverage varies with shingle texture and stain age, so expect to judge as you go.
Right Fit For
Homeowners staring down obvious black streaks on asphalt shingles who want a single product built for that exact job.
A Better Fit Elsewhere
DIYers cleaning broad deck and fence areas may get more mileage from 30 Seconds 2.5G30S Biodegradable Outdoor Cleaner, which dilutes to cover more ground.
If your “roof” problem is really a patio, deck, or fence that sits right beside the house, 30 Seconds 2.5G30S Biodegradable Outdoor Cleaner makes more sense than an asphalt-focused formula. You dilute the concentrate one-to-one with water, spray it on, then rinse.
The 2.5-gallon container covers up to 500 square feet on porous surfaces and up to 1,500 square feet on non-porous ones, so a small roof-side deck or a stretch of siding is comfortably in range. Unlike RMR-86 Pro Contractor Grade, this is designed as a broad-surface rinse rather than a spot stain killer.
Where It Delivers
- Biodegradable formula is gentler on surrounding plants than harsher solvents.
- Generous coverage from a single container handles big deck or driveway passes.
- Spray-on, rinse-off routine keeps the labor side of the project manageable.
- Works across concrete, brick, siding, fences, and decks with one product.
Room For Improvement
- Less aggressive on deep, set-in black algae than a dedicated mold remover.
- The 1:1 dilution step adds a mixing pass before you start spraying.
- A 2.5-gallon jug is bulky to store between projects.
Who Should Grab It
Homeowners who want one cleaner to handle the deck, fence, and the lower roofline edge in a single weekend project.
Swap It Out When
Heavy tar or bitumen spots are the real problem, since Trick Shot Asphalt Solvent and Cleaner is engineered for asphalt and paving residue.
Trick Shot Asphalt Solvent and Cleaner is a different animal from the rest of this list. It’s a biobased industrial degreaser aimed at dissolving asphalt, bitumen, and tar deposits on tools, paving equipment, and yes, stubborn roofing spots.
The 16-ounce bottle is a targeted tool, not a broad roof wash. Reach for it when a recent repair left tar drips on shingles, or when sealants have smeared onto flashing. Where RMR-86 Pro Contractor Grade handles algae, this handles petroleum-based mess.
Well-Handled Touches
- Biobased formula softens the environmental profile of a heavy-duty solvent.
- Time-release action lets the chemistry penetrate without constant re-wetting.
- Small bottle is easy to keep on hand for occasional drip or splash repairs.
Honest Caveats
- Not designed for full-roof algae cleaning, so it won’t replace a dedicated wash.
- Strong solvent smell calls for good ventilation and protective gloves.
- Limited 16-ounce size means a larger spill could outrun the supply on hand.
Perfect Match For
Homeowners and contractors dealing with bitumen, tar, or asphalt sealant smears on roofing and tools after paving or repair work.
Where Another Pick Suits Better
Anyone chasing roof-wide algae streaks will find a more efficient tool in RMR-86 Pro Contractor Grade Mold Stain Remover, which is built for that exact problem.
What Matters Most Before Choosing A Roof Cleaner
Not every roof cleaner earns its keep on the same roof. Algae, soot, and tar each respond to different chemistry, and matching the product to the stain saves hours of scrubbing.
Read The Stain Before You Buy
Black streaks almost always mean algae, which responds to dedicated mold and mildew removers like RMR-86 Pro Contractor Grade. Whitish chalky film or soot near a chimney points to grime that a prep cleaner like Savogran 10621 Trisodium Phosphate handles well. Glossy black smears that smell faintly of road tar signal bitumen, which is where Trick Shot Asphalt Solvent and Cleaner earns its place.
Match Coverage To Roof Size
A two-pound box of TSP concentrates well in a bucket. A one-gallon jug of mold remover covers a moderate asphalt roof face. A 2.5-gallon container of 30 Seconds 2.5G30S Biodegradable Outdoor Cleaner stretches further once diluted, which suits deck-and-siding combo projects.
Think About Safety And Surroundings
Strong cleaners can bleach grass, scorch shrubs, and slick up roof surfaces. Pre-wet nearby plants, plan a stable footing path, and keep a helper nearby when working on a slope.
Smart Choices That Protect Your Roof Long-Term
Pitfalls Shoppers Hit
Reaching for the strongest bleach-based formula on a delicate roof can strip shingle granules faster than it removes stains. Buying a small household cleaner for a full roof wastes time and forces repeat applications. Skipping the rinse step, especially with TSP, can leave residue that interferes with paint or sealant.
Why Top Tier Costs More
Contractor-grade formulas like RMR-86 Pro concentrate active ingredients so a single pass actually removes deep stains instead of lightening them. Larger container sizes lower the per-square-foot cost, and biodegradable bases protect landscaping that cheaper solvents would scorch.
Frequently Asked Questions
Can I use a regular household cleaner on my roof?
Standard household cleaners lack the strength to break down algae or soot on exterior roofing, so you’ll likely see streaks return quickly. A product formulated for outdoor stain removal works far more efficiently.
Is it safe to clean roof shingles myself?
Homeowners comfortable with ladder safety and proper footing can handle a basic roof wash. Steep pitches, multi-story homes, and heavy moss growth are situations where a professional crew is the smarter call.
How often should a roof be cleaned?
Most asphalt shingle roofs benefit from a cleaning every two to three years, depending on tree cover and humidity. Algae-prone regions sometimes need attention every other season.
Will roof cleaning damage shingles?
Gentle, even application with a proper roof cleaner should not damage intact shingles. High-pressure washing is far more risky than a chemical soft wash applied at ground or low-ladder level.
Do I need to rinse plants after using these products?
Yes, pre-wetting surrounding vegetation and rinsing again after application protects leaves and soil from concentrated cleaners. Covering delicate shrubs with a tarp adds another layer of safety.
Closing Thoughts
The best cleaner is the one that matches the stain in front of you, from algae streaks to tar splatter. Pair the product to the problem, give it the dwell time it asks for, and your roof will look noticeably brighter without unnecessary scrubbing.
