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Flat Roof Maintenance
Why Basements Flood
Moss Prevention Duration
Measures 66 and 67
Testimonial - Moss Treatment
Moss removal concrete tiles
Water in Walls
Roof Moss Treatment Service in Portland Oregon
Guaranteed service and Guaranteed results
I guarantee my moss treatment service and guarantee my results. I've only had to retreat ten roofs now in over eight years that I've been in business. And I have easily treated over one thousand roofs.
Who should Treat Roofs
Roofs can be treated by licensed pesticide applicators (regulated by ODA Pesticides division) or homeowners. I have a pesticide license and am trained on safety and application rates. Proper application rates and areas are documented, well proven and easily accessible. Homeowners can also apply zinc sulphate to their roofs. The advantage is that zinc sulphate is inexpensive and long lasting. If you feel comfortable on your roof, you can prevent moss very inexpensively!
When Should Roof Moss be Treated
Roof moss should be treated as soon as it appears. Even if you don't see moss, but the roof is dirty enough, then a preventative rate should be applied. Why? Because it is cheaper to treat moss than it is to treat it and them remove bulky moss later. It saves you money by preventing the moss before it gets started. This keeps the roof cleaner which results in a longer lasting roof.
Moss will continue to grow on roofs and will become more and more noticeable if left untreated.
Moss will not stop growing. During summer it will go dormant. But when it rains, it springs into action, taking over the roof. When moss becomes large and tumbles down the roof, it will fill the gutters and may plug the downspouts, causing them to overflow in the rain.
Green and damp moss readily growing in valleys and shady areas of roof. Please note absence of moss and mildew for one foot below galvanized roof-jack flashing. It is because the roof jack is coated with metallic zinc. Photo by Bradly Lewis
How is Moss Damaging to my Roof?
- Roof Leaks - Moss holds up the edges of the shingles and forms little dams that slow water from running straight down the roof. Water ends up going sideways under the shingles and gets under the shingles to wet the tar paper and roof. This can cause damage to the roof sheathing.
- Prying - Moss has rhizomes that reach around granules. As they soak up water and dry out, their rhizomes work to loosen the granules and pry them from the shingle.
- Loss of Surface Tension - Roof moss holds moisture on your roof. This moisture loosens the surface tension of the tar in the fiberglass shingles and causes the granules to come off prematurely. You need the granules to protect your roof from the ultraviolet (UV) in sunlight and also take the brunt of the hot/cold cycle of the sunlight and night temperatures.
- Freeze/Thaw - Moss holds moisture. During the freeze and thaw cycles of fall and winter, the expansion process of water to ice removes granules from the shingles. You need the granules to protect the tar and fiberglass shingle. Without the granules, the tar shingles dry out more quickly and lose their water repellency.
Moss, lichen, and algae growing on this roof peak.
Important Reasons for Roof Moss Treatment
- Prevent water roof leaks - You want to prevent causes for water damage to your: roof, attic, insulation and ceiling and wall sheet rock and paint.
- Qualify for Home Insurance - Your home insurance policy may not be renewed (they may send you a home inspector and then later a letter in the mail and/or call you) around renewal time if the moss is not killed and or removed. This is an especially valuable time for you to have this moss treatment service available.
- Lower Roof Maintenance Expense - You want to stop the growth of a small amount of moss on your roof and then let the rain wash the dead moss off instead of waiting until there is so much moss that it must be treated and also removed. This moss treatment service will save you money in the long run.
- Prepare for Roof Moss Removal - You want the moss removed from your roof later. Treating the moss first will kill it. This makes it cheaper and easier to remove from the roof later for two reasons:
1) the rhizomes (like roots) withdraw from the shingles
2) the moss breaks up easily and is more easily blown away.
- Keep Roof Drier - You have a flatter roof and the moss growth is holding moisture on the roof that is rotting the plywood.
- Help keep Shingles from Wind Damage - You are in an area that can become windy enough that the shingles held up at the edges by the moss may get blown back and torn off the roof.
- Lower Home Maintenance Cost - You are the one that is responsible for replacing and repairing the roof and you want to keep your home maintenance expenses low.
I pushed down with my finger on this moss to show you how much water it was holding.
Possible Reasons to Not Treat Moss on an Expired Roof
- Tear Off - If you have two layers of composite / 3 tab on your roof, and if the top layer is worthless and and you must tear off all the shingles to reroof shortly, then don't treat the moss.
- House to be Demolished - If the house is going to be demolished in a few months when zoning laws change, then it's a waste of money to treat the moss.
- House not Livable - If the house has been condemned, no one is living in it and it doesn't matter if the roof leaks, then guaranteed moss treatment service is unnecessary at this point.
What I Use for Moss Treatment and Why
- Zinc Sulphate Monohydrate - I use and recommend zinc sulphate on all composite/ 3 tab /fiberglass roofs.
- Widely Available and Commonly Used Zinc is widely available and in use by homeowners and licensed professionals.
- Approved by EPA - It is highly recommended and approved by EPA for moss control and treatment. It is classified as a pesticide (treating moss) and regulated by ODA pesticides division when used by commercial applicators.
- Long lasting. Zinc sulphate is very long lasting on roofs when applied correctly. It typically lasts from 5+ years without reapplying it.
- Inexpensive Zinc sulphate is available in bulk quantities at high purities. This makes it the least expensive moss treatment product on the market.
- Easy Application Zinc can easily be applied to the roof by commercial applicators
- Not an Environmental Threat - It is not in any significant levels in streams or rivers and is not posing a threat to our environment.
- 100 % Effective against All Mosses - Zinc-sulphate (zinc) is 100% effective at killing moss. This allows me to give all my customers a one year warranty against moss regrowth.
- Preventative - Zinc-sulphate also helps prevent moss. You get moss treatment and prevention in one step with no added cost. This saves you money, saves me time and saves wasted energy and materials into the environment.
- Zinc is Common in Building Materials - Metallic zinc is used in lots of building materials already (flashing, galvanized nails, cyclone fences, metal roof jacks, metal roof vents. This makes it more likely to be compatible with other materials on and around your home. Even the roofing nails are coated with zinc and roofing staples too.)
- Good side-effects - Zinc-sulphate also has side effect of mildew prevention.
- Fairly Quick Kill Rate - Zinc takes only 1-3 weeks to kill moss depending on concentration, rainfall, humidity and heat.
- Best kill Method - The moss dies from the roof surface to the tip of the moss.
- Non-Staining - Zinc sulphate does not permanently stain composite roofs. It may leave a dry white light haze (when applied on dry days) but only until the first rain (which happens pretty quick in Oregon and Washington).
- Great Moss Color Change - It usually changes the moss's color from bright green to dark green, brown and sometimes almost black. This makes the moss less noticeable on darker roofs. This can be an advantage if you won't be removing the moss for a while.
- Surface Tension - Zinc sulphate does not decrease surface tension to a point that it would encourage water penetration into the shingles. It is safe on shingles.
- Walkable - Zinc sulphate does not make the surface of the roof slippery with a coating.
Only on concrete tiles is zinc sulphate is noticeable (unattractive) and staining. This is why I don't recommend it specifically for concrete tile roofs. Also it is against federal law to use zinc-sulphate on concrete tile roofs.
Are You Selling your house?
Curb appeal is essential in selling a home especially in a buyer's market. On dry days with large clumps of loose moss, the roof can be green-brushed prior to treatment. This quickly makes your roof look nicer.
How Long Does Your Moss Treatment Last?
Based on six years of experience, the moss treatment will last you about six years. I've been in business nearly six years now and have easily treated over a thousand roofs. I've had several people call me back to treat their roofs, but only nine people now have actually needed another treatment. I guarantee you that my moss treatment will last you a minimum of one year, but from what I see, people are going six years and still haven't need it treated again. Why is this? It's the way I apply it that makes it last so long. If you just sprinkle a treatment on the roof, it may only last a year. And I'm glad it is lasting so long for so many people. I've got tons of new customers and won't run out of work. If you can spend a money on one treatment and it lasts you longer, then that lowers your home maintenance expense. That's great.
What I Don't Use to Treat Moss and Why
There are many items on the market for treating moss that claim to be biodegradable. One of these is ammoniated soap of fatty acids. They claim it is safe for pets and animals. That's great. However in my experience it is marginally effective. I've gotten phone calls from people that have used it on their roof and it seems to have just made the moss grow faster. Often times it will only partially kill the moss. Applying zinc sulphate is not harmful to pets. The pets are required to be inside while the moss treatment process is in progress anyway and zinc sulphate is not harmful to the environment when applied according to Federal guidelines. Because of it's limitations and no superior results in the significant requirements for moss treatment(safe, 100% effective, environmentally safe), I don't use it. It also leaves a coating of fat on the roof that can be slippery if walked on.
FAQs about Moss Treatment
What about pressure-washing the roof?
Pressure-washing is not a moss treatment. It is a violent moss removal process only. I've been told by roofing contractors that it remove 3-5 years of life from the roof as it removes granules. I've seen the results of people who have pressure washed roofs. It removes granules. Also, it doesn't remove all the live moss. Moss rhizomes grow at least one inch under the bottom edge of the shingles. Pressure washing cannot get the "roots" / rhizomes off your roof. Moss may be growing again in a noticeable way in about 6 months. Here are a few reasons why I don't recommend it for the average home owner:
- All the pressure-washers of roofs that I've met don't treat the moss first. This causes more granule loss as pressurized water forces off the moss that is clinging by it's rhizomes/roots to the granules. Again, (this is important) water pressure is used to rip off the moss that is holding onto the granules.
- It forces water between the shingles. Shingles are not water proof. They are only water resistant. Shingles are designed to shed water falling from the sky. They depend on the tar and gravity to carry water off the roof quickly. Pressure-washing forces water into the shingle and in between the shingles.
- Many pressure-washers of roofs are not licensed contractors. The Oregon Construction Contractor Board recently deregulated pressure-washing industry so they are not required to carry insurance to protect your home from damage. Some who pressure wash roofs require you to sign a paper that keeps you from seeking reimbursement for their damages.
- Water and debris runs off the roof so fast that it plugs the gutters and downspouts and overflows onto the house and around the foundation. This requires the house to be pressure-washed also. Pressure-washing creates more work and needlessly wastes time, energy and resources.
Why does moss grow on my roof?
All the things moss needs to grow exist on many areas of your roof. Moss needs water. So you'll find it mostly on shaded parts of the roof. The north side of your roof is often shaded and slow to dry out. Also it grows under overhangs. It won't grow for a few feet under large pieces of galvanized metal because of the zinc runoff there. Also, mildew won't grow downstream from galvanized flashing.
What about using zinc strips?
Zinc strips cannot keep up with moss. There is a lot to say about this.
- Zinc strips won't kill existing moss. They are not even a viable moss treatment solution. One of the first things I learned in studying moss prevention was the ineffectiveness of zinc strips.
- You would have to install them in a special way and put so many on the roof that it does not look good.
- Zinc shingles work better than zinc strips but still cannot keep up with moss in Oregon climate. They would have to be installed every 2 to 4 feet to be effective. Most people would not even consider it because of the unattractive change it would cause in the appearance of the roof.
How soon after I put on a roof will the moss start growing?
From what I've seen, moss will start growing within three years if you have deciduous trees over a shaded part of your roof. If you have no tree nearby and are in the middle of a housing development with low wind, moss will usually be noticeable after 8 years.
Up close and personal: Clumpy moss growing on composition roof. Photo by Bradly Lewis
Will zinc sulphate harm my plants?
Answer is nearly same as above. I've done research and paid for research to be done on using equipment to evenly distribute the least amount of zinc sulphate on the roof. I've made great progress in this area. Also, I check first to see if you gutters drain into the city sewer or if they empty near succulent plants. Succulent plants would be susceptible might be harmed if they are not washed off within a couple hours. Over spray of zinc sulphate is recommended to be washed off plants and paint. Moss is a bryophite, which is a simpler plant and absorbs water through osmosis (cell to cell). It is very susceptible to zinc. It does not have the more sophisticated nutrient delivery method of stems and veins found in woody stemmed plants.
Will zinc sulphate hurt the environment?
The Environmental Protection Agency (EPA) heavily regulates pesticides under the Federal Insecticide, Fungicide, and Rodenticide Act of 1972 and sets stringent standards and tests which must be passed before pesticides, herbicides and rodenticides are allowed on the market. Every so many years they come up for review. Industries must pay large amounts of money in testing, research and development. Chemicals that are ineffective and harmful are quickly weeded out. Zinc sulphate has proven itself effective against moss and safe for the environment. I have been educated on pesticide application and have an operators license for the business and an applicators license for myself. Please also visit the license and contact information toward the top middle of this page.
How Properly Applied Zinc Sulphate Helps the Environment
Following paragraph copied from this government site: http://www.tfhrc.gov/hnr20/recycle/waste/rss1.htm
Approximately 10 million metric tons (11 million tons) of asphalt roofing shingle scrap is generated each year in the United States.(1) It is estimated that 90 to 95 percent of this material is from residential roof replacement ("tear-offs"), with the remainder being leftover material from shingle production ("roofing shingle tabs").
I personally believe after being in business for over five years that using zinc sulphate to extend the life of roofs is a great step in reducing this waste. By preventing moss, you may greatly extend the life of your roof. This saves you money, reduces labor costs, reduces material cost and keeps your roof looking nicer for longer. The means you go longer times between reroofing and have fewer times that you have to tear old roofing material from your home.
"I would highly recommend Brad, who is professional, knowledgeable and friendly. He generously shared his time and expertise during our initial phone conversation, while removing the moss from our roof, and afterward while answering my questions. I definitely plan on contacting Brad again and would not hesitate to refer him to friends and neighbors." - Jan (customer 2010)