by Michael Chotiner of The Home Depot

 

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:

Algae and Moss noted on a roof in Vine Grove

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 and moss noted on a roof in Vine Grove

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.
  • 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.

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.

An ice dam is a ridge of ice that forms at the edge of a roof and prevents melting snow from draining. As water backs up behind the dam, it can leak through the roof and cause damage to walls, ceilings, insulation and other areas.
 
How do ice dams form?
 
Ice dams are formed by an interaction between snow cover, outside temperatures, and heat lost through the roof. Specifically, there must be snow on the roof, warm  portions of the upper roof (warmer than 32° F), and cold portions of the lower roof (at freezing or below). Melted snow from the warmer areas will refreeze when it flows down to the colder portions, forming an ice dam.
Although the primary contributor to snow melting is heat loss from the building’s interior, solar radiation can also provide sufficient heat to melt snow on a roof. For example, in southern Canada, enough sunlight can be transmitted through 6 inches (150 mm) of snow cover on a clear and sunny day to cause melting at the roof’s surface even when the outside temperature is 14° F (-10° C), with an attic temperature of 23° F (-5° C).
Gutters do not cause ice dams to form, contrary to popular belief. Gutters do, however, help concentrate ice from the dam in a vulnerable area, where parts of the house can peel away under the weight of the ice and come crashing to the ground.
 
Problems Associated with Ice Dams
 

Ice dams are problematic because they force water to leak from the roof into the building envelope. This may lead to:

  • rotted roof decking, exterior and interior walls, and framing;
  • respiratory illnesses (allergies, asthma, etc.) caused by mold growth;
  • reduced effectiveness of insulation. Wet insulation doesn’t work well, and chronically wet insulation will not decompress even when it dries. Without working insulation, even more heat will escape to the roof where more snow will melt, causing more ice dams which, in turn, will lead to leaks; and
  • peeling paint. Water from the leak will infiltrate wall cavities and cause paint to peel and blister. This may happen long after the ice dam has melted and thus not appear directly related to the ice dam.

Prevention

  • Keep the entire roof cold. This can be accomplished by implementing the following measures:
    • Install a metal roof. Ice formations may occur on metal roofs, but the design of the roof will not allow the melting water to penetrate the roof’s surface. Also,Notice how the ice is heaviest beneath the chimney, where snow can be melted easily snow and ice are more likely to slide off of a smooth, metal surface than asphalt shingles.
    • Seal all air leaks in the attic floor, such as those surrounding wire and plumbing penetrations, attic hatches, and ceiling light fixtures leading to the attic from the living space below.
    • Increase the thickness of insulation on the attic floor, ductwork, and chimneys that pass through the attic.
  • Move or elevate exhaust systems that terminate just above the roof, where they are likely to melt snow.
  • A minimum of 3″ air space is recommended between the top of insulation and roof sheathing in sloped ceilings.
  • Remove snow from the roof. This can be accomplished safely using a roof rake from the ground. Be careful not to harm roofing materials or to dislodge dangerous icicles.
  • Create channels in the ice by hosing it with warm water. Because this process intentionally adds water to the roof, this should be done only in emergencies where a great deal of water is already flowing through the roof, and when temperatures are warm enough that the hose water can drain before it freezes.

Prevention and Removal Methods to Avoid

  • electric heat cables. These rarely work, they require effort to install, they use electricity, and they can make shingles brittle.
  • manual removal of the ice dam using shovels, hammers, ice picks, rakes, or whatever destructive items can be found in the shed. The roof can be easily damaged by these efforts, as can the homeowner, when they slip off of the icy roof.
In summary, ice dams are caused by inadequate attic insulation, but homeowners can take certain preventative measures to ensure that they are rare.

All GFCI outlets have one little-known flaw: their circuitry eventually wears out, usually after about 10 years, at which point they no longer function properly.

The reset button alone won’t tell you if a pre-2006 GFCI outlet is still working properly—you’ll need to check it with a special tester.

By detecting dangerous current flow and instantly shutting off power, ground fault circuit interrupters save hundreds of lives each year. But after 10 years or so, the sensitive circuitry inside a GFCI wears out. And usually the test button on the GFCI doesn’t tell you there’s anything wrong: When you press the button, it shuts off the power as always. So the only reliable way to check an older GFCI is to use a circuit tester that has its own GFCI test button (sold at home centers and hardware stores).

Plug in the tester and push its test button. If the power goes off, the GFCI is working. Press the reset button to restore power. If the power doesn’t go off, replace the GFCI.

Your new GFCI will never require a circuit tester. All GFCIs manufactured after mid-2006 are designed to tell you when they fail. The vast majority indicate failure by shutting off power permanently. So someday your GFCI (and any other outlets connected to it) will simply stop delivering power and you’ll have to replace it.

How GFCI Receptacles Keep You Safe

Two-thirds of all electrocutions in U.S. homes could be prevented if people installed the receptacles.

By Max Alexander of This Old House magazine

Portable

A ground fault happens whenever electricity escapes the confines of the wiring in an appliance, light fixture, or power tool and takes a shortcut to the ground. When that short cut is through a human, the results can be deadly. About 200 people in the U.S. alone die of ground faults each year, accounting for two-thirds of all electrocutions occurring in homes.

To prevent such accidents, Charles Dalziel, a professor of electrical engineering at the University of California, invented the ground-fault circuit interrupter (GFCI), in 1961. Most of the time, his invention does nothing; it just monitors the difference in the current flowing into and out of a tool or appliance. But when that difference exceeds 5 milliamps, an indication that a ground fault may be occurring, the GFCI shuts off the flow in an instant — as little as .025 second.

GFCIs are required by the National Electric Code in all new kitchens, bathrooms, crawl spaces, unfinished basements, and most outdoor receptacles. Owners of older houses can retrofit $10 GFCI receptacles at those locations or have GFCI breaker switches (which run as much as $108 for 50-amp models) mounted in the main breaker panel. Portable GFCI adapters, which plug into regular wall receptacles, are available for about $40.

“The great thing about GFCIs is that they protect you whether or not your wiring is grounded,” says Bill Grande, manager for safety products at Leviton, a manufacturer of GFCIs. Because lightning and other power surges can damage a GFCIs delicate circuitry at any time, Grande recommends the following monthly test: Plug in a light fixture and turn it on. Then push the device’s test button. If the light stays on, the GFCI needs to be replaced.

<script type=”text/javascript” src=”https://www.nachi.org/transcripts/2.0/NACHI13020504.js”></script><br />Transcript provided by InterNACHI, the <a href=”https://www.nachi.org”>home inspector</a> organization

One of the most common comments I make when inspecting a home is one that points out moisture damage at the exterior door jamb. There are typically a couple potential causes for the damage. It is a common issue that can sometimes be repaired without replacing the door. Using materials that resist rot can help minimize further damage as well as installing a storm door.  Depending on your skill set and the amount of damage, this might be a project you could do yourself. Sometimes the damage can extend to the sub-floor or rim joist. These conditions are more difficult to address on your own.