Central California's
Roofing Expert
What are the warning signs that my roof needs attention?
What can be done about the black streaks on my shingles? (see ALGAE
GROWTH below)

Depicted below are symptoms that indicate your roof may need to be serviced or replaced. Click
on any problem to learn what's causing it and how to fix it. If your roof is in the last 20% of its
expected life, you should probably think about replacing the roof instead of repairing it.













ALGAE GROWTH

  • Causes

Algae growth causes a dark discoloration
on roofs. The algae are usually brown to
black in color which results in a streaked,
dirty looking rooftop. It can be mistaken
for soot, dirt, or tree droppings, which typically produce only localized discoloration. It's caused
by the growth of air-borne algae which deposits spores on your roof. The good news is that
algae growth does not affect the service life of your roofing material. It occurs most often in
warm, humid climates such as the Southeast.

  • Recommendations

Discoloration of roofs caused by algae is difficult to remove, but may be lightened by spraying a
diluted solution of chlorine bleach, trisodium phosphate, and water onto the roof. Solutions
range from one cup TSP, one gallon bleach and four gallons of water, to one cup TSP and 2.5
gallons each of bleach and water. This solution can then be rinsed from the roof in 10 to 15
minutes. Do not scrub. Scrubbing will loosen and remove shingle granules. After spraying be
sure to thoroughly flush the roof and the greenery around the home (grass, bushes and shrubs)
with water. The effectiveness of this type of cleaning may only be temporary, and the
discoloration may recur. High pressure washing is not recommended due to the possibility of
removing shingle granules, thereby shortening the life of the Roofing System.

For a more permanent solution, re-roof with algae-resistant shingles. They are specifically
designed to inhibit most algae growth for extended periods of time and are usually backed by
some type of manufacturer's warranty.


Buckling

  • Causes

Wrinkled or improperly applied
applied over old, rough shingles
Roof deck movement from absorbed
moisture

Poor roof ventilation


  • Recommendations

Remove the shingles that are affected. Cut the wrinkle in the felt or smooth the original layer of
shingles and replace the new shingles.

Add ventilation to the attic space. According to most building codes, you need one square foot of
vent area for each 150 square feet of attic floor space. The minimum is one square foot for
every 300 square feet of attic floor space, if the space is balanced between the ridge and intake
vents. A balanced ventilation system means that about 50 percent of the required ventilating
area should be provided by vents located in the upper portion of your attic to serve as exhaust
vents, with the remaining 50 percent provided by eave vents for intake.


Curling

  • Causes

High nails

Improper number of fasteners per shingle

Lack of ventilation


  • Recommendations

Check location and number of fasteners to insure that the shingles are installed per the
manufacturers instructions. If high nails are present, use a hammer to make the nail head flush
with the top of the shingle.

Add ventilation to the attic space. According to most building codes, you need one square foot of
vent area for each 150 square feet of attic floor space. The minimum is one square foot for
every 300 square feet of attic floor space, if the space is balanced between the ridge and intake
vents. A balanced ventilation system means that about 50 percent of the required ventilating
area should be provided by vents located in the upper portion of your attic to serve as exhaust
vents, with the remaining 50 percent provided by eave vents for intake.


Damaged Flashing

  • Causes

Improper installation on a new roof

Drying and cracking on an old roof

Dented or bent by severe weather or
extreme temperatures

Settling of the structure


  • Recommendations

In most cases it is only necessary to remove and replace the flashing and shingles around the
damaged area.




Missing Granules

  • Causes

Normally a certain number of
granules will be loose, especially
after application. These granules
are called "riders" and are a normal
result of the manufacturing process.
Granule loss does not affect the service life of the shingles unless the loss is severe enough to
expose the asphalt or fiberglass mat.


  • Recommendations

On aging shingles, missing granules indicate a need for replacement.

Following a hail storm, a sudden increase in granule loss is an indicator of possible hail damage.



Missing Shingles

  • Causes

Improper fastening

Exposure to high winds


  • Recommendations

Replace shingles which have completely blown off.

Remove and replace shingles which have broken tabs.

For shingles with tabs blowing up and down, hand seal the shingles with an asphalt plastic
cement, commonly referred to as flashing cement. This roofing cement must comply with ASTM
D4586 -- Type I or Type II which is the standard specifically for asbestos-free asphalt plastic roof
cement.

To hand seal, lift each tab of a 3-tab shingle and apply two spots of the cement under each tab.
Each spot should be approximately the size of a quarter and placed 1" to 2" from each end of
the tab and near the bottom. Laminated shingles require 4 spots of cement per shingle. After
application, press the tab down firmly to start the bond. Be careful not to apply the cement too
close to the bottom of the tab. This causes the cement to squeeze out when the tab is pressed
down.



Ceiling Spots

  • Causes

Spots are caused by leaks in the roof.

  • Recommendations

Check attic for leaks in deck.

Check chimney and vents for cracks in flashing.

Check rafters for leaks that "travel" away from original source.

Check eaves for water backing up from ice dams.

Check roof for damaged or missing shingles.



Rotting

  • Causes

Rotting is caused by absorption of moisture
by the mat at the core of the shingle.
This is a common problem with
organic-based shingles.


  • Recommendations

Replace with fiberglass mat shingles.



Blistering

  • Causes

Moisture in the shingle


  • Recommendations

If the blisters break open revealing the asphalt, the affected shingles should be replaced.
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