Click here to go to the Structural Pest Control Service website of the Texas Department of Agriculture.

by Michael Chotiner of The Home Depot With Modifications by Robert Hughes

Stains on asphalt roofing shingles make a house look shabby, which detracts from its value. In some cases, stains are merely a cosmetic issue.  But sometimes they’re symptomatic of a problem that, if left unchecked, can lead to more serious damage and, eventually, roof failure. It's not always hard to distinguish the causes of stains, nor, in most cases, to get rid of them and prevent the stains from recurring.

Common Causes of Staining

Dark stains on an asphalt roof could be caused by a number of conditions, including:

Eroded mineral surface. If the roof-covering material has been on the house for 15 years or so, it could be that the surface granules are wearing off the shingles and the asphalt base is starting to show through. On older roofs, you may additionally see cracked and/or shingles with curled edges. If you determine that age and wear are the causes of darkening, it may be time for a new roof.

Algae growth. More often than not, blue, green or black stains on an asphalt-shingle roof are caused by algae. Algae staining begins with small spots which, over time, can develop into streaks. Algae stains, which are often mistaken for mold or mildew, aren't harmful to anything other than the appearance of asphalt shingles, but nobody likes the look.

Algae-stained asphalt-shingle roof (photo by author)

Moss. Green, velvety masses of moss often grow on north-facing roof surfaces and on tree-shaded roofs. Unlike algae, moss left on roof surfaces can develop beyond an aesthetic problem. It can infiltrate the roof structure underneath the shingles and make their edges lift and curl, which can lead to cracking and blow-off during high winds and storms. Heavy moss growth can actually form dams that can cause water to back up under the shingles and damage the roof deck. It's best to clean moss off a roof as soon as you notice it's growing there.

 

Safety First 

Both algae and moss can be easily removed from asphalt shingles with a 50/50 solution of chlorine bleach and water. Laundry-strength bleach is sufficient, or you can opt for any of a number of proprietary roof cleaners, some of which don't contain bleach, lye, or other potentially harmful chemicals.

Since bleach and some cleaners can be harmful to plants and humans, it's a good idea to take some precautions when working with them, including the following:

• Wait for a calm, windless day to clean your roof.
• Spray landscape plants near the house with water and cover them with tarps to protect them from chemical overspray and runoff.  If you cannot control the run-off (by catching the water from the downspouts.  Then use a low chlorine solution of 10 percent chlorine and 90 percent water.  Then you can leave it on for a longer period of time.
• Wear protective clothing, including long sleeves, pants and gloves, as well as goggles to protect your eyes, and shoes with high-traction soles.

Before climbing up to clean stains from your roof, be aware that about 30,000 people fall off ladders and roofs each year.  Consider using a safety harness, just as the pros are required to do, and follow the common-sense rules for properly positioning and using a ladder, which can be found in InterNACHI’s article on ladder safety.  Also, be sure to notify someone that you’ll be on your roof.  In case of an accident that incapacitates you, you’ll want someone to know where to look for you.

Upgear by Wenner Safety Harness (photo courtesy of The Home Depot)

How to Clean Algae and Moss from a Roof 

Apply the bleach solution with a garden sprayer. Let it stand on the surface for about 20 minutes, then rinse it off with spray from a garden hose. Don't let the bleach solution stand on the roof for more than 30 minutes or so without rinsing. And don't use a pressure washer, which can damage the shingles by removing their protective layer of asphalt granules.  Please note that the water run-off may damage the plants because of th chlorine.  If the roof is equipped with gutters, you may want to direct the run-off water from the downspouts into a container.

If accumulations of algae or moss are heavy, at least some of it should wash off the roof surface right away with the stream from the hose. You can try brushing off algae and moss with a brush or broom with medium-stiff bristles, but don't scrub too hard. You don't want to separate the mineral granules from the shingles.

If chunks of algae or moss or heavy stains remain on the surface after rinsing, let the roof dry, then spray on the bleach solution again. Wait 30 minutes and rinse. Don't worry if some staining remains after the second rinse. It should wash off over time with exposure to rain and sunlight.

How to Prevent Algae and Moss Stains from Recurring 

Algae and moss tend to grow roof surfaces that are shaded and retain moisture. So, it’s a good idea to cut away tree branches that overhang the roof and block sunlight. Keep the roof surface clean by blowing off leaves and fallen branches during seasonal maintenance.

The red lines indicate where to install sacrificial metal strips 
to prevent algae and moss growth.

For long-term stain prevention, have zinc or copper strips installed under the cap shingles, leaving an inch or two of the surface exposed at roof peaks, along hips, and under the first course of shingles at the base of dormers. Copper and zinc are sacrificial metals that shed tiny bits of their surface with each rainfall. The metals coat the roof and inhibit organic growth for many years.

Following these maintenance tips can help homeowners enjoy an attractive roof.  They can also help extend the roof’s service life, which is important whether you plan to stay in your home or sell it in the future.

Most people don’t know how easy it is to make their homes run on less energy, and here at InterNACHI, we want to change that. Drastic reductions in heating, cooling and electricity costs can be accomplished through very simple changes, most of which homeowners can do themselves. Of course, for homeowners who want to take advantage of the most up-to-date knowledge and systems in home energy efficiency, InterNACHI energy auditors can perform in-depth testing to find the best energy solutions for your particular home.

Why make your home more energy efficient? Here are a few good reasons:

• Federal, state, utility and local jurisdictions' financial incentives, such as tax breaks, are very advantageous for homeowners in most parts of the U.S.
• It saves money. It costs less to power a home that has been converted to be more energy-efficient.
• It increases the comfort level indoors.
• It reduces our impact on climate change. Many scientists now believe that excessive energy consumption contributes significantly to global warming.
• It reduces pollution. Conventional power production introduces pollutants that find their way into the air, soil and water supplies.

1. Find better ways to heat and cool your house. 

As much as half of the energy used in homes goes toward heating and cooling. The following are a few ways that energy bills can be reduced through adjustments to the heating and cooling systems:

• Install a ceiling fan. Ceiling fans can be used in place of air conditioners, which require a large amount of energy.
• Periodically replace air filters in air conditioners and heaters.
• Set thermostats to an appropriate temperature. Specifically, they should be turned down at night and when no one is home. In most homes, about 2% of the heating bill will be saved for each degree that the thermostat is lowered for at least eight hours each day. Turning down the thermostat from 75° F to 70° F, for example, saves about 10% on heating costs.
• Install a programmable thermostat. A programmable thermostat saves money by allowing heating and cooling appliances to be automatically turned down during times that no one is home and at night. Programmable thermostats contain no mercury and, in some climate zones, can save up to $150 per year in energy costs.
• Install a wood stove or a pellet stove. These are more efficient sources of heat than furnaces.
• At night, curtains drawn over windows will better insulate the room.

2. Install a tankless water heater.

Demand-type water heaters (tankless or instantaneous) provide hot water only as it is needed. They don't produce the standby energy losses associated with traditional storage water heaters, which will save on energy costs. Tankless water heaters heat water directly without the use of a storage tank. When a hot water tap is turned on, cold water travels through a pipe into the unit. A gas burner or an electric element heats the water. As a result, demand water heaters deliver a constant supply of hot water. You don't need to wait for a storage tank to fill up with enough hot water.

3. Replace incandescent lights.

The average household dedicates 11% of its energy budget to lighting. Traditional incandescent lights convert approximately only 10% of the energy they consume into light, while the rest becomes heat. The use of new lighting technologies, such as light-emitting diodes (LEDs) and compact fluorescent lamps (CFLs), can reduce the energy use required by lighting by 50% to 75%. Advances in lighting controls offer further energy savings by reducing the amount of time that lights are on but not being used. Here are some facts about CFLs and LEDs:

• CFLs use 75% less energy and last about 10 times longer than traditional incandescent bulbs.
• LEDs last even longer than CFLs and consume less energy.
• LEDs have no moving parts and, unlike CFLs, they contain no mercury.

4. Seal and insulate your home.

Sealing and insulating your home is one of the most cost-effective ways to make a home more comfortable and energy-efficient, and you can do it yourself. A tightly sealed home can improve comfort and indoor air quality while reducing utility bills. An InterNACHI energy auditor can assess  leakage in the building envelope and recommend fixes that will dramatically increase comfort and energy savings.

The following are some common places where leakage may occur:

• electrical receptacles/outlets;
• mail slots;
• around pipes and wires;
• wall- or window-mounted air conditioners;
• attic hatches;
• fireplace dampers;
• inadequate weatherstripping around doors;
• baseboards;
• window frames; and
• switch plates.

Because hot air rises, air leaks are most likely to occur in the attic. Homeowners can perform a variety of repairs and maintenance to their attics that save them money on cooling and heating, such as: 

• Plug the large holes. Locations in the attic where leakage is most likely to be the greatest are where walls meet the attic floor, behind and under attic knee walls, and in dropped-ceiling areas.
• Seal the small holes. You can easily do this by looking for areas where the insulation is darkened. Darkened insulation is a result of dusty interior air being filtered by insulation before leaking through small holes in the building envelope. In cold weather, you may see frosty areas in the insulation caused by warm, moist air condensing and then freezing as it hits the cold attic air. In warmer weather, you’ll find water staining in these same areas. Use expanding foam or caulk to seal the openings around plumbing vent pipes and electrical wires. Cover the areas with insulation after the caulk is dry.
• Seal up the attic access panel with weatherstripping. You can cut a piece of fiberglass or rigid foamboard insulation in the same size as the attic hatch and glue it to the back of the attic access panel. If you have pull-down attic stairs or an attic door, these should be sealed in a similar manner.

5. Install efficient showerheads and toilets.

The following systems can be installed to conserve water usage in homes:

• low-flow showerheads. They are available in different flow rates, and some have a pause button which shuts off the water while the bather lathers up;
• low-flow toilets. Toilets consume 30% to 40% of the total water used in homes, making them the biggest water users. Replacing an older 3.5-gallon toilet with a modern, low-flow 1.6-gallon toilet can reduce usage an average of 2 gallons-per-flush (GPF), saving 12,000 gallons of water per year. Low-flow toilets usually have "1.6 GPF" marked on the bowl behind the seat or inside the tank;
• vacuum-assist toilets. This type of toilet has a vacuum chamber that uses a siphon action to suck air from the trap beneath the bowl, allowing it to quickly fill with water to clear waste. Vacuum-assist toilets are relatively quiet; and
• dual-flush toilets. Dual-flush toilets have been used in Europe and Australia for years and are now gaining in popularity in the U.S. Dual-flush toilets let you choose between a 1-gallon (or less) flush for liquid waste, and a 1.6-gallon flush for solid waste. Dual-flush 1.6-GPF toilets reduce water consumption by an additional 30%.

6. Use appliances and electronics responsibly.

Appliances and electronics account for about 20% of household energy bills in a typical U.S. home. The following are tips that will reduce the required energy of electronics and appliances:

• Refrigerators and freezers should not be located near the stove, dishwasher or heat vents, or exposed to direct sunlight. Exposure to warm areas will force them to use more energy to remain cool.  
• Computers should be shut off when not in use. If unattended computers must be left on, their monitors should be shut off. According to some studies, computers account for approximately 3% of all energy consumption in the United States.
• Use efficient ENERGY STAR-rated appliances and electronics. These devices, approved by the U.S. Department of Energy and the Environmental Protection Agency’s ENERGY STAR Program, include TVs, home theater systems, DVD players, CD players, receivers, speakers, and more. According to the EPA, if just 10% of homes used energy-efficient appliances, it would reduce carbon emissions by the equivalent of 1.7 million acres of trees.
• Chargers, such as those used for laptops and cell phones, consume energy when they are plugged in. When they are not connected to electronics, chargers should be unplugged.
• Laptop computers consume considerably less electricity than desktop computers.

7. Install daylighting as an alternative to electrical lighting.

Daylighting is the practice of using natural light to illuminate the home's interior. It can be achieved using the following approaches:

• skylights. It’s important that they be double-pane or they may not be cost-effective. Flashing skylights correctly is key to avoiding leaks;
• light shelves. Light shelves are passive devices designed to bounce light deep into a building. They may be interior or exterior. Light shelves can introduce light into a space up to 2½ times the distance from the floor to the top of the window, and advanced light shelves may introduce four times that amount;
• clerestory windows.  Clerestory windows are short, wide windows set high on the wall. Protected from the summer sun by the roof overhang, they allow winter sun to shine through for natural lighting and warmth; and 
• light tubes.  Light tubes use a special lens designed to amplify low-level light and reduce light intensity from the midday sun. Sunlight is channeled through a tube coated with a highly reflective material, and then enters the living space through a diffuser designed to distribute light evenly.

8. Insulate windows and doors.

About one-third of the home's total heat loss usually occurs through windows and doors. The following are ways to reduce energy lost through windows and doors:

• Seal all window edges and cracks with rope caulk. This is the cheapest and simplest option.
• Windows can be weatherstripped with a special lining that is inserted between the window and the frame. For doors, apply weatherstripping around the whole perimeter to ensure a tight seal when they're closed. Install quality door sweeps on the bottom of the doors, if they aren't already in place.
• Install storm windows at windows with only single panes. A removable glass frame can be installed over an existing window.
• If existing windows have rotted or damaged wood, cracked glass, missing putty, poorly fitting sashes, or locks that don't work, they should be repaired or replaced.

9. Cook smart.

An enormous amount of energy is wasted while cooking. The following recommendations and statistics illustrate less wasteful ways of cooking:

• Convection ovens are more efficient that conventional ovens. They use fans to force hot air to circulate more evenly, thereby allowing food to be cooked at a lower temperature. Convection ovens use approximately 20% less electricity than conventional ovens.
• Microwave ovens consume approximately 80% less energy than conventional ovens.
• Pans should be placed on the matching size heating element or flame. 
• Using lids on pots and pans will heat food more quickly than cooking in uncovered pots and pans.
• Pressure cookers reduce cooking time dramatically.
• When using conventional ovens, food should be placed on the top rack. The top rack is hotter and will cook food faster. 

10. Change the way you do laundry.

• Do not use the medium setting on your washer. Wait until you have a full load of clothes, as the medium setting saves less than half of the water and energy used for a full load.
• Avoid using high-temperature settings when clothes are not very soiled. Water that is 140° F uses far more energy than 103° F for the warm-water setting, but 140° F isn’t that much more effective for getting clothes clean.
• Clean the lint trap every time before you use the dryer. Not only is excess lint a fire hazard, but it will prolong the amount of time required for your clothes to dry.
• If possible, air-dry your clothes on lines and racks.
• Spin-dry or wring clothes out before putting them into a dryer.