Roof Cleaning Ideas

QUESTION: Why does the HOA require homeowners clean to their roofs of debris, algae, moss, etc.?

ANSWER: Under Article VIII - Section 8.06 Maintenance of Building and Grounds of the HOA Covenants homeowners have the responsibility to maintain the exterior of their homes. This include removing unsightly debris and cleaning algae, moss, mildew, etc. from the roof.

The purpose of this page is to provide information, suggestions and ideas on roof cleaning. The information contained within is to be used at the homeowner's own risk and in no way shall the Longwood Green Homeowners Association be held liable as a result of homeowners damaging their roof or voiding their roof warranty. Always do your own research and verification before using any method and this is also true when hiring a roof cleaning contractor. Homeowners concerned about damage to the roof as a result of cleaning need to avoid methods employing mechanical or hydraulic pressure to the shingles. Chemical cleaning is the preferred method for removing algae stains, however, homeowners are cautioned to select a contractor who uses appropriate roof cleaning agents which will not damage the roof. There are several DOs and DON'Ts regarding roof cleaning and these are covered in the 2014 Winter Edition of the community newsletter.

Be aware that 99% of the time "professional" roof cleaners are using sodium hypochlorite plus additives to clean asphalt shingle roofs in Florida. Household bleach contains 6% sodium hypochlorite whereas professionals typically purchase sodium hypochlorite at 12% strength then dilute it as appropriate. This is why you may have noted the scent of bleach after a professional cleaning. Sodium hypochlorite, also known as liquid chlorine, is typically used for algae/moss treatment in swimming pools. Other additives may include TSP (Tri-Sodium Phosphate) and/or a surfactant such as "Roof Snot" or similar to their mixture. Don't be fooled by contractors who attempt to ease your fears about using bleach by calling it sodium hypoclorite or attempt to make it sound like these are "professional cleaning agents that only "licensed professionals" have access. Sodium hypochlorite (bleach) is recommended by the Asphalt Roofing Manufacturers Association for proper cleaning of roofs. It is the only solution that will provide an immediate or dramatic effect versus other solutions that gradually remove algae over weeks or months.


Wet & Forget (W&F)
Costs $30 - $40 per gallon. Takes about 2.5 gallons W&F for a typical 2,000 sq-ft home. Sprayed on with a low pressure pump sprayer. Mixed at a 5:1 ratio of water to W&F to create 6 gallons of sprayable solution per 1 gallon of W&F concentrate. Can take up to 3-6 months to fully clean the roof and lasts up to one year before requiring another treatment. Should only be sprayed when roof is shaded such as just prior to sunset and when no rain is expected for at least 6+ hours. Can also be used to clean driveway and walkway.

Spray & Forget (S&F)
Product is similar in concept to W&F. Product is slightly lower in cost as compared to W&F. Follow instructions on label.

Jomax Roof Cleaner
Follow instructions on label.


HTH Algae Guard 10 (Make-It-Yourself Wet & Forget)
HTH Algae Guard 10 ($10 Ace Hardware) is an algaecide containing 10% Benzalkonium Chloride (DimethylBenzylAmmoniumChloride) exactly like W&F therefore it is mixed at the same 5:1 ratio. Add 2 ounces of Fabuloso to each gallon of solution. Fabuloso acts as a surfactant so the solution applies and sticks better. This mixed solution is to be applied exactly as you would W&F therefore apply when no rain is expected for at least 6+ hours and do not rinse roof off. NOTE: HTH Algae Guard also comes formulated as a 30% and 60% formulation therefore dilute as appropriate. For example, HTH Algae Guard 60 ($17 Walmart) can be mixed at a rate of 3.5oz into 1 gallon of water plus 2oz Fabuloso. A 32oz (1 quart) container of HTH Algae Guard 60 can make 9 gallons of sprayable solution.

HTH Algae Guard 10 $10/1gallon makes 6 gallons of solution = $1.67/gal
HTH Algae Guard 60 $17/1quart makes 9 gallons of solution = $1.89/gal
Wet & Forget $30/gallon makes 6 gallons of solution = $5/gal

Copper sulfate is an inorganic compound that combines sulfur with copper. It can kill bacteria, algae and fungi. It is highly toxic to fish therefore do not allow it to runoff into waterways. In a nutshell copper sulfate 20% solution is made by dissolving store bought copper sulfate crystals into water until the water is at saturation level automatically stopping at 20% and leaving extra crystals undissolved. Create a roof cleaning solution by mixing copper sulfate 20% solution to water at a 10:1 ratio or 1 quart copper sulfate 20% with 10 quarts water. Spray onto roof and do not rinse.

Household Bleach
Use of common household bleach (6% sodium hypochlorite) is the most common method used. Mix at a ratio of 1:1 bleach to water (1/2 of the spray solution will be household bleach). Apply with a pump sprayer and allow to sit for 15 to 20 minutes then gently rise away. Runoff can kill plants and lawn so be sure to cover plants or wash down lawn at drip line. A 2,000 sq-ft home is expected to require approximately 10-12 gallons of household bleach. 1/4 cup of Tri-Sodium Phosphate (TSP) per gallon of solution may be added as a surfactant allowing the bleach to stay put longer rather than runoff onto the ground. NOTE: Never mix ammonia based products with household bleach as the two generate poisonous chlorine gas.

Oxygen Bleach plus Tri-Sodium Phosphate (TSP)
Oxygen Bleach contains sodium percarbonate, different than household bleach which is 6% sodium hypoclorite. It does many of the same things household bleach does but it’s not toxic. Oxygen bleach is the preferred bleach to use for cleaning your roof if you want to create your own solution because it won’t harm you, pets or plants. A solution of oxygen bleach, trisodium phosphate (TSP) and water can be effective. Mix 2 cups Oxiclean, 1 cup TSP (Tri-Sodium Phosphate) into 3 gallons hot water to allow the crystals to disolve. Apply this mixture with a garden sprayer, let it sit on the roof surface for 20 to 30 minutes, then rinse with low-pressure water.


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