If you live in a humid area of the country, you’ve probably seen unsightly dark streaks on asphalt shingle roofs. Though often attributed to an accumulation of dirt, defective shingles, mold, or mildew; the most common culprit is actually a blue-green algae known as Gloeocapsa Magma that is spread by airborne spores. While algae growth does little harm to roofing, the stains don’t help the overall appearance or resale value of your home.

Areas Susceptible to Algae Stains

You may also have noticed that algae stains are absent directly below the metal flashing around chimneys or roof vents. This is due to fact that copper and the zinc coating on galvanized sheet metal are toxic to algae. Every time it rains, trace amounts of metals are washed down the roof, inhibiting algae growth.

Absence of algae under metal flashing

Algae Resistant Shingles

In recent years, roofing manufacturers have begun mixing copper granules, such as those from 3M Scotchgard, into roofing products to produce algae resistant shingles. If you live in an area susceptible to algae growth, be sure to specify this type of shingle when replacing your roof.

Chemical Cleaning

Algae stains can be removed by cleaning, though they usually return. While an occasional cleaning might not harm your roof, repeated use of harsh chemicals, or the erosive effects of pressure washing, can damage or shorten the life of asphalt shingles.

There are several products on the market specifically designed to remove algae stains from roofs, such as Spray and Forget and Moss Out!. A mixture of trisodium phosphate (TSP), bleach, and water will also remove stains. Oxygen bleach lightens stains as well and is less harmful to the environment, but it doesn’t produce as immediate or dramatic an effect as chlorine bleach. To learn more about oxygen bleach, go to The Laundry Alternative, Inc.

Roof cleaned with oxygen bleach (left) and chlorine bleach (center). Galvanized vent (right) prevented algae growth.

Here’s what you’ll need to clean your roof:

• Cleaner
• Pump sprayer
• Garden hose with spray nozzle
• Safety glasses or goggles
• Rubber gloves
• Safety rope
• Old clothes
• Slip resistant shoes
• Ladder

Safety

Working on a roof can be dangerous, and it becomes even more hazardous when wet, so be sure to take adequate safety precautions. Avoid working on steep roofs, wear slip resistant shoes, and use a safety rope where needed. When working with harsh chemicals, be sure to protect your skin and eyes.

Bleach can damage or kill other plants in addition to algae, so wet down any grass, shrubs, or other plants where runoff will occur before and after applying bleach. Covering bushes with plastic after wetting them down helps as well.

Cleaning

It’s best to clean your roof on a cloudy day to prevent the cleaner from evaporating too quickly. If you know the manufacturer of your shingles, contact them or check their website for specific recommendations on cleaning. When using a product made for cleaning roofs or oxygen bleach, follow the directions on the container.

While the recipe for cleaning a roof with bleach can vary, the basic formula is:

• 1 quart bleach (6% sodium hypochlorite)
• ¼ cup TSP (trisodium phosphate)
• 1 gallon water

Pour the ingredients into a pump type garden sprayer, mix well, and spray.

After wetting down the roof with the solution, allow it to remain on the roof for about 15 minutes before rinsing off with a hose.

Prevention

To keep algae from coming back once your roof is clean, install a strip of copper or zinc coated sheet metal along each side of the roof just below the ridge. To be effective, 2”- 4” of metal should be visible on the roof.

While copper is more toxic to algae, galvanized sheet metal is much less expensive. Both copper and galvanized metal are available in rolls of various widths and thickness both online and from local metal suppliers. You can also purchase zinc strips specifically made to eliminate roof algae from Z-Stop.

Narrow strips of sheet metal can be attached directly to your roof using roofing nails or screws with a rubber washer. For wider pieces of sheet metal, loosen the self-sealing tabs on the top row of shingles with a putty knife, slip part of the sheet metal under them, and nail it in place under the shingles with roofing nails.

The methods used to eliminate and prevent algae on your roof can also be applied to moss.

I just bought a house with a roof section that has a 1 to 2 inch pitch, should I use rubber roofing or are shingles acceptable? Thank you for your time, Mike

Mike,

The usual slope for asphalt shingles is a 4” or greater rise for every horizontal foot of run. A 3” per foot slope is considered low, but may be acceptable if a double layer of felt is used. Some building codes allow as low as a 2” slope with asphalt shingles if additional steps are taken. For anything less than that, you should use a roofing material specifically made for low slope roofs.

From natural materials like slate and wood to manmade products such as asphalt, sheet metal, and plastic polymers; there are more types and styles of roofing to choose from today than ever before. While each has its advantages and shortcomings, they all can add a distinctive design element to your home. So which one is right for you?

What to Look for in a Roof

There are many factors to consider when selecting a roof including:

• How long will it last?
• Does it hold up during natural disasters such as wildfires or hurricanes?
• Is it too heavy for the existing roof framing?
• Does the roof have enough slope?
• Will the look complement the style of the house?
• Is the type of roofing allowed by local building codes?
• And finally, how much does it cost?

Pros and Cons

Some types of roofing may be better suited for your house than others. Factors such as the slope of the roof and strength of the framing could limit your choices. In areas prone to wildfires or hurricanes, look for a product with a high fire rating or good wind resistance. In addition, steps can be taken during the installation of many types of roofing to improve their resistance to fire or wind. Below is a rundown on the different types of roofing available.

Asphalt Composition Shingles

Photo Courtesy of CertainTeed Corporation

• The most popular roofing for homes, comprising over 80% of residential roofing.
• Made of either an organic fiber mat (better for cold weather and wind resistance) or fiberglass (more fire and moisture resistant) which is then impregnated with asphalt and coated with mineral granules.
• Available in either traditional 3-tab shingles or thicker laminated “architectural” shingles.
• Algae resistant shingles are available in humid climates to prevent staining.
• Moderate in weight.
• Can be used on fairly low to steeper sloped roofs.
• Good fire resistance, fair wind resistance.
• Inexpensive.

Metal

Photo Courtesy of Metal Sales Manufacturing Corporation

• May be composed of steel, aluminum, copper, or zinc alloy.
• Steel roofs come with either a zinc coating or painted finish.
• Copper roofs are installed unfinished and acquire a protective green patina with age.
• Available in sheets or in shingles that resemble other materials.
• Absorb a third less heat than asphalt.
• Made up of mostly recyclable material.
• Can be installed with the fasteners hidden (standing seam) or exposed.
• Lightweight.
• Available for low or steep sloped roofs.
• Good resistance to both fire and wind.
• Moderate (steel) to expensive (copper) in price.

Plastic Polymer

Photo Courtesy of EcoStar

• Molded from a high-tech plastic polymer material.
• Available in a number of different styles that resemble slate or wood shakes.
• Expected to be long lasting and low maintenance.
• Made from recycled materials and can be recycled again when replaced.
• Light (ArmorLite) to moderate (EcoStar) in weight.
• Can be used on moderate to steep sloped roofs.
• Good fire and wind resistance.
• Moderate in price.

Clay Tile

Photo Courtesy of Ludowici Roof Tile

• Traditional Italian or Spanish look, can also be made to resemble wood shakes or slate.
• Color can fade over time.
• Long lasting and low maintenance, but brittle and can break.
• Heavy, requires reinforced roof framing to support.
• Can be used on moderate to steeper sloped roofs.
• Excellent fire resistance, fair to low wind resistance.
• Expensive.

Concrete Tile

Photo Courtesy of Eagle Roofing Products

• Can be made to resemble traditional clay tiles, wood shakes, or slate.
• Color can be throughout tile or only applied on the surface.
• Long lasting and low maintenance but can break.
• Heavy, requires reinforced roof framing to support.
• Can be used on moderate to steeper sloped roofs.
• Excellent fire resistance, fair to low wind resistance.
• Moderate in price.

Slate

• One of the oldest roofing materials.
• Requires specially trained workers to install.
• Long lasting, durable (varies depending on where it was quarried).
• Heavy, requires reinforced roofing structure to support.
• Steep sloped roofs only.
• Good resistance to fire and wind.
• Very expensive.

Wood

• Available in sawn shingles or split shakes.
• Commonly made of cedar, but can be made of other rot resistant woods as well.
• Gives natural look, weathers to a silvery gray.
• Short lifespan, requires periodic maintenance.
• Moderate in weight.
• Can be used on moderate to steep sloped roofs.
• Good wind resistance, poor fire resistance (can be treated with a fire retardant).
• Moderate in price.

Roofing Comparison

The following table gives an overview of the various materials available. Weight and cost are listed per square of roofing (100 square feet) and include both labor and materials. Actual price may vary depending on the particular product used, the complexity of the job, and labor costs in different parts of the country. The cost per year indicates the price of the labor and materials per square over the roof’s projected life.

Warranties

There are two warranties to consider when roofing your home. The manufacturer’s warranty covers defects in the roofing material. A separate warranty may be issued by the roofing contractor to handle problems arising from improper installation.

A warranty is no better than the company that writes it, so make sure the product comes from a reputable manufacturer with the financial resources to stand behind it. This applies to the roofing contractor as well, since a fly-by-night roofer may be long gone before their guarantee expires.

It is important to read the warranty carefully to see what is covered and excluded. Some warranties are not transferable when you sell your house while others are limited to the cost of materials or are prorated over time.

Your roof is your home’s single most important defense when it comes to protecting it from the elements, so it makes sense to make sure it’s done right.

Related Links

• National Roofing Contractors Association
• How to Hire a Roofer
• Is Your Roof Warrenty Worth the Paper It’s Written On?

Asphalt:

• Asphalt Roofing Manufacturers Association
• CertainTeed

Tile:

• Tile Roofing Institute
• Clay Tile: Ludowici Roof Tile
• Concrete Tile: Eagle Roofing Products

Metal:

• Metal Roofing Alliance
• Metal Sales Manufacturing Corporation

Plastic Polymer:

• EcoStar
• ArmorLite Roofing Technology

Slate:

• National Slate Association
• The New England Slate Company

Wood:

• Cedar Shake and Shingle Bureau
• Goat Lake Forest Products

Installing a rain diverter over the doorway to your house will make life a little easier the next time you come home during a downpour. While diverters are available at many building supply stores, they are not hard to make if you have trouble finding them.

Materials Needed

• Sheet aluminum
• Two straight 2×4s
• Two 3” or larger clamps
• Rubber mallet
• Utility knife
• Straight edge

Sheet aluminum is sold by the roll in the roofing section of building supply stores. You will need a piece 8” wide and two feet longer than the width of the door you plan to cover. While sheet aluminum can be cut with tin snips or even scissors, you can get a smoother more accurate cut using a utility knife and a straight edge such as a framing square.

Lay the aluminum sheet on a flat surface and cut it to length by scoring along the straight edge several times with a utility knife. Bend the aluminum back and forth along the mark until it breaks. Cut the sheet lengthwise to 8” wide using the same method.

Sandwich the sheet of aluminum between the 2×4s, leaving 2” protruding, and clamp it in place. The edges of the 2×4s must be straight and line up with each other, otherwise the bend will cause wrinkles in the sheet metal.

Start at one end and push down on the protruding aluminum while working toward the other end. Repeat this process several times until the sheet has been bent to a right angle.

Using the rubber mallet, or a hammer and block of wood, tap along the edge to finish the bend.

Remove the clamps and attach the diverter to the roof as detailed in the article Installing a Rain Diverter.

Nothing is more annoying than having to walk through a waterfall coming off your roof to reach the front door every time it rains. Fortunately, there’s an easy and inexpensive solution to the problem.

Rain diverters are available at most building supply stores including The Home Depot. They are easiest to install on asphalt roofing and consist of an “L” shaped piece of sheet metal that fits under the roofing above the entranceway.

First, cut the diverter about a foot longer on each side than the area you want to keep dry.

Center the diverter over the area to be covered using a plumb bob or a string with a weight attached. Using a pry bar or putty knife, loosen the second row of shingles up from the edge of the roof where the diverter will be located.

Slide the diverter under the shingles.

Slant the diverter so that one side is slightly lower than the other to allow for drainage. A drop of 1” is plenty for a 6′ diverter.

Carefully lift up the shingle tabs to keep from breaking them, and nail the diverter in place with roofing nails. Position the nails so they will be covered by the shingles and are a few inches up from the bottom edge of the overlapping shingles.

Dab roofing cement on the nail heads, under each shingle tab, and in any gaps between the shingles to keep water from getting underneath the diverter. Press the shingles down to seal them back in place.

That’s all there is to it. Now you won’t get soaked on the way to the mailbox when it rains.

Be sure and clean behind the rain diverter from time to time to keep leaves and other debris from building up.

Maintaining gutters and downspouts is one of the most often overlooked jobs around the house. It is also one of the most important, since clogged or leaking gutters can quickly lead to rotten fascia boards, peeling paint, or worse.

Importance of Gutters

While it might be tempting to do away with your gutters all together, they serve an important function in areas that receive more than 15” to 20” of rain a year. Gutters direct water away from the house to protect your siding, foundation, and landscaping. Without them, siding can rot, basements flood, and flower beds erode.

Gutter Guards

Though gutter guards allow you to go longer between cleanings, they’re far from foolproof and need to be checked periodically. Pine straw and leaves often become lodged in them, and smaller debris can still filter through to cause big problems. Shielding gutters doesn’t prevent leaks or keep hangers from working loose either.

Cleaning Gutters

To clean gutters, you’ll need a ladder, a garden trowel, bucket lined with a trash bag, a hose, a rag, and a helper. If you encounter serious clogs, you may also need a plumber’s snake.

After you have removed any gutter guards, use the trowel to scoop leaves and debris from the gutter into the bucket.

Add the collected material to a compost pile if you have one, or dispose of it with other lawn debris.

Once the gutters have been cleaned, check the downspouts for clogs by inserting a hose with a rag wrapped around it so that water will be directed through them.

Have your helper turn the water on full force, and check to make sure it is flowing freely from the end of the downspout.

If a downspout has a clog that can’t be cleared with water pressure, use the plumber’s snake to break it up, then use the hose to flush out any remaining debris.

As a last resort, disassemble the downspout and remove the clog. Once the downspout is running freely, start at the far end of the run and rinse the gutter thoroughly with the hose.

Inspection and Repair

After they are clean, inspect and repair the gutters and downspouts as necessary. Make sure all hangers are securely fastened, and use a carpenter’s level to check that the gutters have the proper slope and are not holding water. They should slant down toward the downspouts about ¼” every 10’.

If a section sags, snap a chalk line on the fascia, and remove the hangers in the area.

Measuring from the chalk line, lift the gutter up and reposition the hangers to hold it in place. Water is heavy, and gutters should have a hanger every 2’ as well as within 1’ of any seams.

Now that your gutters are secure and have the correct slope, check them for leaks by running water through them with a hose. Mark any leaks and allow the gutter to dry out thoroughly before patching them with gutter sealant.

Caulking or roofing cement can also be used, and specially formulated self-sticking patches are available to cover damaged areas.

If sealing a joint in the gutter or downspout doesn’t stop the leak, disassemble the joint if possible, clean the two parts, and put them back together using sealant.

Now that your gutters are in tip top shape, check them from time to time while it is raining. If water is spilling over the edges or not running freely from the downspouts, make a note to clean them again as soon as possible.

In this episode we tell you when its time for a new roof, where to start and walk you through the roofing process.

Just as you might head to a showroom to get ideas for your kitchen or bathroom remodel these homeowners headed to a roofing design center to find out what was available in the world of roofing and to purchase their new roof. While roofing design centers are few and far between this one gave the homeowners the opportunity to see different types and colors of roofing material on their home using a digital image of their home and some computer software. The best part - the design center did all the work, from taking the digital image, to using the software to visualize the new roof, to tearing off the old roof and putting on a new one.

After removing the old roofing material and felt beneath the roof decking was cleaned and inspected for damaged. Large sections of decking were removed and replaced as needed before re-roofing began with dimensional asphalt shingles.

We also had a chance to check out various other roofing materials both in the showroom and out on the job. The alternative materials available today offer a variety of looks to compliment different architectural styles, but one of the most attractive things about them is their durability. For instance, one recycled rubber and plastic roofing material, which mimicked slate came with a 50 year warranty. Metal is another popular roofing option, especially in areas prone to high winds. One such roofing material by Decra looked like a traditional shingled roof but was actually a system of interlocking metal panels with a stone chip coating to protect the surface and make it look just like shingles.

If you don’t have a roofing design center in your neck of the woods, finding a roofer by word of mouth may be your best bet. For your protection look for a roofer who has both general liability insurance and worker’s compensation insurance. You’ll also want to ask if they have any certifications from the manufacturer of the products they install. This is a good sign that the work will be done right. Finally, ask for references from their past customers and look at the work they’ve done.

Right away, I know many of you are wondering where you can find a roof design center. I hope more of these will begin popping up nationwide, but it’s fairly new in the wide scope of retail shops. The good news is they are continuing to grow in popularity as more people are finding out how convenient they are. Right now they have eight locations scattered in Florida (Daytona, Tampa, Orlando, Hudson, Jacksonville, Sarasota, Clearwater, Ft. Myers), and one in Mobile, AL. However, in the next year they will be expanding into Raleigh, NC in March of 2007. If you are wondering what the plans are for future development, shoot an email to eric@roofdesigncenter.com.

When it comes to roofing, one of the most common questions I have been asked is if it is advisable to install roofing over an existing roof. Certainly, this has been a common practice since about 1970, but usually only to asphalt shingle roofs or rolled roofing. But the fact that it CAN be done has nothing to do with whether or not it SHOULD be done. My experience has proved that the only benefit is saving money in the up front cost. You won’t have to pay for the old shingles to be removed or disposed of, but that’s the one and only benefit. Personally, I think the practice of re-roofing should be banned. There are far too many problems that can result and they greatly outweigh the cost of removal and disposal of existing shingles. For example, if the existing shingles are cupped or curled, the new shingles are going to be influenced by the shape of the roof beneath them. Your new shingle roof will look very rough. Even though longer nails have to be used for a re-roof job, the old shingles have a tendency to expand and contract with changing weather and can easily cause a “nail pop” to occur. This means the nail will literally be pushed up and through the new shingles, which is a guaranteed roof leak. Take some friendly advice, and always have the existing roof removed before ever installing a new layer of shingles.

A final word of advice on cleaning your roof. You can drive down practically any street in the United States and spot a roof that has ugly black stains and streaks all over it. Black staining is caused by the growth of algae and fungus spores that land on your roof. These spores need three things to grow: heat, moisture and some kind of nutrient. The nutrient comes from dirt and the shingle itself, primarily the limestone filler used in manufacturing the granules. Typically, the politically correct advice is to have a professional roof cleaner take care of it. I will follow the same political correctness by making that recommendation. But now that the web censors are gone….I would always tackle this job myself and save a lot of money. The important thing to remember is safety first. Any time you are on a roof, there is the risk of falling. A good boot, like Cougar Paws (http://www.cougarpaws.com), is a smart thing to wear to avoid slipping. The cleaning process is fairly simple. You can purchase a roof cleaner at a home center, but be careful. Many of these cleaners will contain harmful chemicals. Never, ever use lye or a chlorine bleach product, even if a roofer said it was okay. He’s not very informed if he tells you that. Aside from being harmful to the plants and your gutters, chlorine bleach will erode your shingles stripping them of years of service. Do some research on the internet for an environmentally friendly product. Check out the ingredients and ask for references. A good place to start is http://www.roofraider.com. They have some good photo examples and a toll free number to call and ask questions.

Other Tips From This Episode

The short, dreary days of winter are a good time to think about adding skylights to brighten up dark rooms. Even small units make a big difference in the way rooms look and feel.

There are many brands and several styles to choose from. But I advise my clients to stay away from inexpensive units with plastic glazing. Although they are cheaper initially, the bottom line is they don’t last and many of them leak. The better choice is a high-quality curbed skylight with energy-efficient glazing — and the factory flashing kit made for it. The kit won’t add much to the cost, but it will mean a leak-free installation.

Skylights come as venting units, which open, or as fixed units, which don’t. A venting unit might seem like a good idea, but it is inconvenient to open and close when it’s out of reach. In fact, many customers who order them later tell me they rarely bother to track down the special rod needed to operate their windows. So unless the skylight will be easily accessible, buy the fixed unit and save yourself some money.

This even applies to putting a skylight in a bathroom. But it’s essential to make sure the room has adequate ventilation so condensation doesn’t become a problem. A vent fan for a small bathroom should provide 1 cu. ft. per minute of air circulation per square foot of floor area, or about eight air changes per hour. For more on sizing a vent fan, go to the Website of the Home Ventilating Institute.

Old-fashioned skylights were simply a single thickness of glass in a frame, but today they come with laminated or tempered glass, and low-e and tinted coatings to control heat transmission and UV radiation. Just like windows, skylights are rated for their thermal efficiency by the National Fenestration Rating Council. You can compare the U-values as well as heat and light transmission rates of various skylights. Even though tinted glass is available, I generally recommend that you stick with clear glass because it lets in more light. If intense sunlight does cause too much heat buildup or begins to fade carpeting and furniture inside, add a shade or screen.

Skylights are available in sizes that fit standard 16- or 24-in. on-center framing. Adding a large skylight means that the installer will cut one or more rafters (see illustration). This is not difficult when the roof is conventionally framed — rafters on the sides of the rough opening are doubled up and headers are added at the top and bottom of the opening. But a truss roof is different. Trusses are carefully engineered to carry roof loads, and modifying them in the field is a bad idea. If your home has trusses, make sure the installer sticks with units made to fit between roof members, or gangs several smaller skylights together to create a larger window.