Bleach for Killing Moss on a Roof

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WHY STORE BOUGHT BLEACH ISN’T STRONG ENOUGH TO KILL MOSS

There is a common misconception that bleach can kill moss. Homeowners go into their local supermarket and pick up a jug, pour it on their roofs and wonder why the moss hasn’t died. This information is faulty because, originally, store bought bleach only contained 6% of its weight as Sodium Hypochlorite [A.K.A Bleach].

6% bleachMIXTURES AREN’T ALWAYS SO CLEAR

There are many faulty ehow recipes on how to mix the bleach. By the time you’re done with even a conservative, 1 part bleach to 3 parts water your mixture isn’t strong enough to kill the moss you were after. Mixing household bleach which originally held 94% of its volume as water with even more water makes for a product that is not potent.

Bleach is about $6 a gallon at this time of writing. It takes about 40 gallons of liquid to properly cover an average homes roof.The roof cleaning costs quickly add up.

Let’s take a look at how easy this can be to screw up, and how difficult it can be for an average consumer to properly and correctly clean his roof:

Original Amount of 6% Bleach

Amount of Water

Strength after Dilution

Gallons of mix required for average 1200 Square foot home

Gallons Total:

1 gallon

33%

4%

40

Bleach: 30 g

   H2O: 10g

You now need a surfactant (something to stop the mix from rapidly flowing into your gutters), Dawn* soap or any surfactant able to mix without causing a reaction to bleach, work well. This is a surfactant that works well with bleach and doesn’t take away from its shelf life.

The mix above is a standard mix roof cleaners use to kill moss. Many times depending on the bleaches shelf life, the mixtures need to be adjusted. Bleach is a very volatile solution that loses its strength quickly and doesn’t handle well with a whole host of surfactants. Mixing the wrong surfactant can be wasteful and leave you with a mixture that doesn’t do what it was supposed to which is to:

  • Kill Moss.
  • Remove Stains.
  • Not Damage the roof it is applied to.

We’ve covered everything except how to get 40 gallons of liquid onto your roof ……. [Continued shortly in: pumps for roof cleaning]

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Soft Wash Roof Cleaning Seattle

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Chemical Roof Cleaning

Soft-washing involves the use of chemicals to clean roofs. This method is employed to lessen the amount of damage caused by power-washing. Power-washing on average removes 3-4 layers of granules per cleaning . A roof is known by its years of life:

  •  A 20 year roof has 20 layers of granules.
  •  A 50 year roof has 50 layers of granules.

The soft-wash method when used properly is far more beneficial to roofing substrate then power-washing. No granule loss happens when chemicals are sprayed on your  roofing. Additional benefits include:

  • The elimination of all moss spores that cause moss to grow in the first place.
  • A much longer lasting finished product; on average the process lasts 2-3 years

ARMA [Asphalt Roof Manufacturers Association] recommends soft-wash cleaning for proper roof maintenance. ARMA is the association that governs the making of asphalt shingle roofing. They are the leaders in the industry in the production and proper cleaning methods of roofing materials.

The difference in the finished look of the product : power-washing versus chemical cleaning is nearly indistinguishable, when the proper chemicals are used. A soft wash roof cleaning company generally use a few standard chemical products:

  • TSP [trisodium phosphate]. Known for its ability to remove algae and rust stains
  • Sodium Hydrochloride 10% or higher: known for its ability to kill moss and clean shingle.
  • Borax Lo: A soap like product known to aggressively kill weeds, spores and moss residual.
  • Isopropyl Alcohol: used when aggressive moss has been growing for long periods of time.
  • Surfactant:  used to slow the mixtures path down to the gutter line.

When mixed properly these chemicals generate a long lasting safe products to roofing material. These chemicals are not readily available to the average consumer and the mixtures of this chemical call for exact amounts for a strong enough product. The procedure of soft wash roof cleaning in Seattle is best left to a professional roof cleaning company.

 

Methods of Roof Moss Removal in Seattle

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Over 10,000 roofs are replaced per year due to water intrusion, in the Seattle area. Roof Moss is a major contributing factor to the number of roof replacements. Moss grows in patches 1-3 inches wide. Homes with infrequent sunlight or under foliage are the most prone to moss growth. Large patches of moss trapping moisture in 1-3 inch mats create water dams that then begin pushing water underneath roofing substrate. The roofing material is never left to dry out.The consequences are:

  • Rot.
  • Mildew
  • Buckling

What is Roof Mold?

Bryophytes are soft plants that grow in mats and clumps. They reproduce through periodic release of airborne spores. They have no vascular system to feed themselves as plants with roots do. Bryophytes therefore grow where moisture is prevalent. The Seattle region with between 72-88 days of sunshine a year is an inviting environment for moss growth. Our lack of sun is the reason moss grows so heavily in the area. With no ability to control our amount of sunshine, we are left to do periodic maintenance.

Differing Methods of Moss Control

You can speak to any 2 roof cleaners in the country and the proper method for roof cleaning and moss control is always up for debate. There are standard methods of moss control practiced around the country these methods are:

  • Power washing to remove moss.
  • The use of zinc strips.
  • Chemical treatment.

Power Washing 

Pressure washing without adequate chemical treatment afterwards is the least effective method in killing moss. Without the use of a moss inhibiting chemical you’re left with a roof that will need another cleaning almost immediately. There have been several studies done on the damage a power washer can do to asphalt granules.  ARMA [Asphalt Roofing Manufactures Association] recommends not using a pressure washer on asphalt shingles for roof moss removal. Their primary concern is the loss of granules. Although not as good on asphalt shingles, a power-washing is probably the only effective way of properly cleaning cedar and metal roofs.

The metal roofing vent prevents moss growth.

Zinc Strips

Zinc Strips are effective means of containing moss growth. Due to the cost and the amount of coverage required to kill moss, many times it is unfeasible to use this method. For Zinc strips to successfully control moss growth they must be placed every 3 feet from the tip of the roof to the gutter line. This method is very unsightly and many homeowners do not like the look of Zinc strips going down their entire roof line. The picture above shows CLEARLY, that zinc and metal DO stop moss from growing. Where the metal vents are present; no moss is growing directly beneath them.

To effectively use zinc strips:

  1. Two inches of zinc should protrude the asphalt shingle.
  2. They should start at the ridge cap and end 3 feet above the gutter.

Chemical Treatment of Moss

Chemical treatment, also called soft wash roof cleaning, in our opinion, is the most effective means of moss control. Using the right chemicals, completely kills all moss spores and prevents new moss from rebuilding. Most soft wash roof cleaner’s offer warranties of 1-5 years, they are secure in offering these warranties because they know that it took years for this moss to grow on your roof and it will take years for it to grow back, provided the right chemicals are used in strong enough doses.

The decision on what method is the right method for roof cleaning in Seattle is always up for debate. PWNG uses the chemical soft washing method to soundly control moss. We stand by our service and offer a 1-year warranty with every roof cleaning in Seattle. We look forward to any comments or questions our readers might have and we welcome an open discussion on roof cleaning.

Roof Cleaning FAQ

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PWNG ROOF CLEANING FAQ [frequently asked questions]

 

 

 

Why is there still moss on my roof?

Your roof was not power washed, depending on your roof slope we either (a) manually scrubbed large patches with a stiff bristle brush or (b) chemically sprayed your roof and allowed Mother Nature to take its course.

 

How long does it take for the moss to come off my roof?

Dependent on the weather and sunlight conditions 3 days to 3 weeks. Your roof was sprayed with a mixture similar to weed killer. We live in a very moist climate and at times sunlight is infrequent.[i] After spraying your moss it is left moist and wet on your roofing. Its roots are dead immediately. Sunlight dries your moss out and then rain washes it down your gutters. Hoping to be as cautious as possible to your roofing, our process isn’t immediate[ii].

What was sprayed on my roof?

A mixture known as PSAUCE©[iii]. This is the method your shingle manufacturer recommends for roof cleaning. You can see the PDF by clicking here.[iv] We added Borax-Lo[v] that keeps moss from returning.

 

Is this bad for my plants?

 

Yes and No. We’ve taken every precaution to protect your plant life by not over spraying past your gutter line and washing down any plants that were touched with our chemical. Simply put we are at your residence to kill a plant and there is not a green way to do that. If we damage any plant life we will do our best to resolve the situation with you.

 

How long does the process last?

You are covered for one year from the day you hired us[vi]. Many of our customers have reported no moss growth for 2-3 years and as many as 5! The information we have garnered has helped us create a chemical blend that works. There are over 10,000 roofs a year who fail due to moss in our area. Wet and damp moss locks and holds moisture on your roof. Large patches create a dam and the shingles underneath begin curling and swaying. We have done as much as possible to protect your roof from damage during cleaning and have made moss growth very inhospitable. Thank you for choosing us. We look forward to keeping you as a happy customer for years to come.


[i] KOMO NEWS [cites 58 days of Sun a yr.]

[iii] RCIA [Roof Cleaning Institute of America]

[iv] ARMA[American Shingle Manufacturers Association]

[vi] PWNG [refer to your warranty]

Seattle Roofs Need Cleaning

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Seattle roofs need cleaning for the simple fact that our atmosphere dictates it. Moss grows in moist conditions where sunlight is indirect or infrequent. On average Seattle roofs need cleaning 2x a year. PWNG has developed and worked with a chemical mix that delivers a fatal blow to moss on asphalt shingles  that lasts double the amount of most of our competitors.

Take a look around you and you will see that Seattle roofs need cleaning. On a recent day on one of my rare days off I looked over a hill and saw a sea of green roofs, overlooking Lake Washington.

Left unchecked, these roofs will need replacement, in a very short amount of time. The cost for these replacements might be a good thing for our economy since Seattle replaces more roofs per year then just about every big city, but if I had the choice Id rather spend my money on something I want rather than on something I was forced to buy!

Make no mistake the cost of a seattle roof that needs cleaning is far less then a seattle roof that needs replacement. About 15k dollars less on average!