Pressure roof cleaning is one the methods used to remove dirt and destructive microorganisms from rooftops. Generally, roof cleaning is an important aspect of roof maintenance since it prevents roof decay which often results in repairs and worse cases, roof replacement, it also ensures the roof looks presentable.

Read on to learn more about what pressure washing is, how it works, how much it costs, equipment,systems and solutions used plus the pros and cons.

What is Pressure Roof Cleaning/Washing?

This is the process whereby high-pressure water is blasted on roof surfaces to get rid of mold, grime, algae, and debris on the roof surface. 

There are some factors to consider before cleaning the roof on your own or hiring a contractor to do the job:

  • Using proper cleaning products and appropriate equipment, a homeowner can personally clean the roof but should keep in mind the following factors:
  • Look for a trustworthy cleaning company that offers multiple formulas and preservative solutions
  • Taking ones’ time in cleaning roof surfaces, proper cleansing takes time.
  • Applying the right procedures, rinsing methodology and correct chemicals offer minimum damage to the shingles.
  • Roof algae is not only an aesthetic concern but offer greater concern- Algae causes deterioration of shingles which may lead to the replacement of roofs
  • Considering the cost of repair and replacement of damaged roofs, cleaning isn’t overpriced

It is also important to note that various roof cleaning contractors have their preferred tools and procedures on how to pressure clean a variety of roofs.

Cost of Pressure Roof Washing-How much & what determines the Cost?

On average most contractors charge per square inch with the price varying between $1730 and $3680 to get rid of most dirt and debris accumulated on rooftops. A typical fire hose has a pressure of up to 300 psi while a typical garden hose has a pressure of 80 psi.

Moss removal and treatment could be part of this expense while some contractors include it as an extra expense.  Moss treatment is essential in preventing their growth once again. It costs up to $200.

There are several factors that determine pressurized roof washing. They include:

Frequency of cleaning the roof

Contractors offer different rates and discounts depending on a customer’s frequency in pressure cleaning their roof. Annual services cost less than cleaning the roof once in a decade. However, to maintain the quality of the roof it is advisable to clean the roof at least once in two years. For customers living in humid areas, it is advisable to clean at least once a year.

Size of the roof

An average roof is approximately 1800 square feet. A household owner with a smaller roof would incur fewer charges in pressure cleaning compared to one with a larger roof. Moreover, steep roofs containing gables always incur an extra cost of approximately $0.15 per foot.

Location of the house and height of the roof

Cleaning contractor prices are based on one-story apartments. For a multiple story building, a homeowner should prepare to incur at least $0.1 per foot.

The location of a house and climatic conditions also affect the pressure cleaning cost. Considering coastal regions that have intense salt buildup, cleaning such roofs would incur more cost since it takes longer to get rid of salt.

Extra services offered such as coating

Coating a roof averagely costs $980 while pressure cleaning the roof costs an extra $430. Coating is used to seal the metal roof and thus reflects sunlight and is useful in repelling water, therefore gets rid of clogged water.

Equipment, Systems and Solutions(chemicals) used in Power Roof Wash

Equipment and Systems

During pressure cleaning, the following equipment is necessary:

  • Garden hose with a jet spray or water blaster which focuses the spray
  • An electric water pump to boost water pressure.
  • Pressure washer for rinsing
  • Water broom
  • Pitch Witch (TM) tools

Solutions/Chemicals used in pressure roof washing

This is accomplished using:

  • regular bleach or a solution containing sodium percarbonate
  • 12.5% sodium hypochlorite mixed with water
  • Zinc sulfate solution

 Power Washing Pros

  • It is effective in removing stubborn stains when gentle scrubbing proves ineffective
  • It increases the lifespan of a roof by getting rid of germs.
  • It reduces energy expenses considering algae and fungus on rooftops tend to absorb heat. These keep households warmer and forces owners to invest in air conditioners.
  • It saves on money considering the cost of replacing a damaged roof and energy costs resulting from algae and other plants growing on rooftops.

Roof Pressure Cleaning Cons

  • It uses more water compared to soft washing.
  • Use of intense pressure causes damage to roof materials such as dent and side pitting
  • Intense pressure results in peeling paint from roofs
  • Pressure and harsh chemicals used always destroys vegetation.
  • The high power involved in a high power wash of about 4000 psi results in power wastage as opposed to soft washing that uses less power.
  • Water tends to infiltrate roofing material, due to high pressure, resulting in leakages which pose great health risks to homeowners

High Pressure Vs Low-pressure Roof Cleaning

High-pressure washing and low-pressure options are suitable for different tasks as using the wrong option often results in damaging roofs, repairs, and avoidable maintenance costs.

In high-pressure washing, pressurized water penetrates the roof surface and thus removes debris and tough stains with ease using force. Most homeowners desire this option since it is impressive. It is however recommended for extremely tough surfaces due to its damaging capability such as removing paint. This option always causes premature leaks, removes asphalt and wears out shingles.

Low-pressure washing involves cleaning using lower pressurized water. This option remains to be effective as it minimizes damage as opposed to high pressure cleaning This method cleans effectively and extends the lifespan of roofs.

Frequently Asked Questions

Can you pressure wash an RV rubber roof?

By using an adjustable nozzle and setting the pressure to 1000 psi, pressure can be used on a rubber roof. Rubber roofs are made using rubber or fiber. It is recommended that brush washers are used in cleaning rubber roofs as opposed to high pressure due to their soft and tender nature.

Is it bad or OK to power wash a roof?

It is okay to power wash a roof, however, precautions need to be taken considering how the danger and damage high-pressure washers leave on roofs. While perching on a ladder, blowback from hose pipes often throws off cleaners.

How long does it take to power wash a roof?

On average, it takes between one to two hours to power wash any house. It takes about 30 minutes to set up equipment as well as pack up once cleaning is done. Cleaning involves two parts, application of cleaning bleach and rinsing of the roof to get rid of chemicals.

Can I power wash moss off my roof?

Power washing of moss on roof shingles should not be attempted. High pressure always scraps off granules on the shingles. Therefore, it reduces the lifespan of the roof. 

How often can you pressure wash your roof?

It is recommended that a pressure wash is done at least every two years. Regions experiencing heavy storms require pressure washing more frequently. One should abide by HOA rules to minimize damages done to roofs.

Can you pressure wash an asphalt roof?

Generally, it may be unnecessary to pressure wash an asphalt roof for purposes of removing debris since it damages the protective grit coating on shingles. Sweeping and rinsing using a regular hose is equally effective.

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