Roof cleaning in Northampton and Lehigh County, PA
Roof cleaning in Northampton and Lehigh County, PA

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51 W. End Trail #552

Macungie, PA  18062


Telephone:  610-966-3500


Mobile Users Click HERE: 610-966-3500




Hydro Scrub provides pressure washing services to Berks, Bucks, Lehigh, Montgomery, and Northampton Counties, including the cities of Allentown, Bethlehem, and Whitehall, PA.

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Exterior Building Cleaning, House Washing Services in Lehigh, Northampton, Berks, Montgomery and Northampton Counties, including Allentown Exterior Building Cleaning & House Washing
Composite Deck Cleaning, Trex Deck Cleaning, Composite Deck Cleaning
Roof cleaning, roof washing, asphalt roof cleaning, tile roof cleaning Roof Cleaning / Roof Washing
Deck cleaning, deck washing, deck treatment, wood restoration Wood Restoration
Concrete cleaning, sidewalk cleaning, paver cleaning, brick cleaning, pool deck cleaning, walkway cleaning, chewing gum removal "Hard Surface" Cleaning
Awning cleaning, patio cover cleaning, canvas awning cleaning Awning Cleaning
Power washing, power wash, pressure washing, pressure wash, water pressure cleaning Miscellaneous Power Wash Services


CAUTION:  High pressure roof cleaning / roof washing should be AVOIDED as it can damage your roof!


Hydro Scrub offers no pressure and low pressure roof cleaning / roof washing services to meet your exterior building cleaning & house washing needs.  Hydro Scrub's low pressure roof cleaning method follows Asphalt Roofing Manufacturers Association guidelines.  Using this technique ensures that your shingle warrantee is not voided by improper cleaning chemicals or methods. 


Hydro Scrub cleans all roof types...asphalt, wood (cedar), terra cotta, and slate.  Asphalt shingle roofs are typically the most common roofs which undergo roof cleaning.


Roofs generally have three undesirable growths on them.....algae (i.e., black streaks / stains), moss, and lichen (often also found growing on trees).  Wikipedia claims that 6% of the earth's surface is covered with lichen.  The spores and food supplies of these undesirable growths are everywhere in the environment.  When the spores and their food (pollen, dust, etc.) have access to their final ingredient for growth they flourish.  Moisture is that final ingredient. 


Optimal conditions for algae, moss and lichen growth can usually be found on the north side of almost any stationary surface, be it your roof, a tree, a brick wall, etc.  Why?  Well, the north side of surfaces receives less sunlight, and consequently, takes longer to dry than other sides exposed to sunlight.  This lingering or enhanced moisture allows the algae, moss or lichen to grow and flourish.  Starve the algae, moss, or lichen of moisture and it will not grow.  This is why roofs and other stationary objects facing south usually do not have algae, moss or lichen issues, UNLESS they are shaded by trees, or other structures and/or are receiving moisture from an unnatural source (e.g., maybe a downspout receiving air conditioning condensate, or maybe a block downspout which takes forever to drain).

Roof severely impacted with lichen.

The algae which causes the unsightly black streaks is called Gloeocapsa magma.  It is easily removed during roof cleaning / roof washing because its root structure is quite shallow and weak.  Moss often grows as soft, fluffy clumps or patches and lichen often grows as "flowering", "hard" clumps are much more difficult to remove than algae because they possess a much stronger, deeper, aggressive root structure.  Of the three, moss or lichen are usually the most damaging to your roof, but even algae can have negative effects.  Sometimes, lichen actually consume the colored granules of roof shingles and once the lichen is removed, it leaves a black spot in its former location.



Both no pressure and low pressure roof cleaning / roof washing consist of applying a cleaning solution to your roof which kills the algae, moss and lichen.  After application of the cleaning solution, the roof is either left alone to be rinsed by mother nature's rain (no pressure method) or is rinsed via low pressure by the contractor (low pressure method).  The results are the same, it just depends on how fast you wish to see results.  The characteristics of no pressure and low pressure roof cleaning are as follows:


No Pressure Roof Cleaning

  • Roof usually does NOT have to be "walked".
  • Cleaning solution is applied.  Undesirable growths on roof are killed. 
  • Mother nature does the rinsing of the roof.
  • Poor method if immediate visual results are desired, especially if moss and/or lichen are present.
  • Can result in a blotchy or streaked roof appearance until the roof is thoroughly rinsed by heavy rainfalls. 
  • Can take several weeks to months for moss and lichens to be removed from the roof.  While the algae stains are removed almost immediately, moss and lichens, due to their deeper, more aggressive root structure take a while to release from the roof surface.
  • Because time is NOT spent rising the roof, it is the less costly option.


Low Pressure Roof Cleaning

  • Roof surface generally has to be "walked".  If roof pitch is too steep for walking, a man-lift is often required, increasing the project cost significantly. 
  • Cleaning solution is applied.  Undesirable growths on roof are killed. 
  • Contractor rinses the roof with a wide, low pressure rinsing tip or other low pressure method.
  • Good method if immediate visual results are desired.
  • Moss and lichens are immediately removed from the roof.  
  • Because time is spent rinsing the roof, and time is money, it is the more costly option. 





Many customers ask about roof "sealers"?  In short, there is no roof "sealer" on the market which will prevent the algae, moss, lichen from coming back.  If the environmental conditions of spores, food and moisture are met, algae, moss and lichen can grow on your roof.  That is the truth. 


Roof cleaning is a multi-million dollar business around the country, and it is growing.  Think about this.  If national manufacturers of roofing shingles do NOT have a sealer for your roof, your local roof cleaning contractor certainly does not.  If there is so much money to made in selling roof "sealers", why are "sealers" not applied at the manufacturing level as an option or incorporated directly into the shingles?  If your local roof cleaning contractor has a roof "sealer" that works, why hasn't he sold it to the roof manufacturers and retired?  In other words, the chance of your local roof cleaning contractor developing a multi-million, national capable, product and only selling it to his local customers is ridiculous.  If someone is selling you a roof "sealer", you should probably show them the exit.... and promptly. 





There are two options to minimize the chances of having algae, moss, lichen issues on your roof.  The first is to purchase and install asphalt shingles that have metallic copper pieces embedded into each shingle.  The second is to install strips of copper or zinc across roof ridges and peaks, which may or may not be aesthetically pleasing in appearance.  The science behind using copper, zinc or any heavy metal for that matter, is that the metallic copper granules and the copper or zinc strips, when exposed to our slightly acidic rain, release small concentrations of copper or zinc across the roof during precipitation events.  The copper and zinc are poisonous to the algae, moss, and lichen.  Such retards or complete inhbits their growth.  The same method is used to control algae in aquariums. 


Additionaly, the above explains why objects painted with lead based paint, rarely, if ever, have algae, mold or mildew growth on them!  While this may be hard to believe, the fact is our "concern for the environment" and our use of "safer" or "greener" materials is causing our environment to be over run by "organisms" which were previously "controlled" by man's routine use of certain materials.  Such is the Law of Unintended Consquences! 





When tasked to provide roof cleaning services, Hydro Scrub almost always conducts exterior gutter brightening services as well.  Such services are conducted at an additional cost to our basic roof cleaning service.


The reason exterior gutters must be brightened as a result of roof cleaning is because as the roof cleaning solutions run down and off the roof, they often splash onto the exterior of the gutters.  Even a little splash or "overspray" causes the gutters to become "clean" in a spotted or streaked manner.  In order to restore the appearance of the exterior of the gutters uniformly, the gutters are subjected to physical brushing with a speciality cleaning solution and then rinsed.  Unfortunately, surfaces exposed to cleaning solutions need to be rinsed from the top down and this is simply one of those cases. 


Please browse our photo gallery of completed projects in our Roof Cleaning Photo Gallery to see what you can expect from our roof cleaning services.


Hydro Scrub welcomes the opportunity to provide an estimate or our professional advice on your roof cleaning / roof washing concerns as well on other services we offer.  Please feel free to contact us to discuss your project.

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Hydro Scrub | 51 W. End Trail #552, Macungie, PA 18062 | (610) 966-3500 |