Roofing Frequently Asked Questions by Home Owners

Discoloration or Streaking of Roof

About four to five years following installation some roofing may start showing dark streaks. These streaks most often show up on the north-facing roof side and may be mistaken for grime or shingle granules falling off. The darkness is usually the result of algae growing in roofing area getting less exposure to the sun.

Moisture & Algae

Slopes of roofing that are shaded or get less sunlight routinely retain moisture for more time resulting in algae growing. The streaks and dark areas are an aesthetic issue and do not reduce the life of the roofing system or its waterproofing characteristics.

Use Caution if Cleaning

Remember to use care when trying to remove these streaks as many harsh treatments or power washing may hurt your roof system and result in asphalt shingle granules falling off.

Faster Wear on One Side of a Roof

In most areas, the southern roof slope will wear out more quickly than the other roof sides as it gets the majority of the sunlight. Over the lifetime of a roof the sunlight will disintegratte all roofing material.

Dripping of Water Between Gutter and Roof Shingles

This is normally caused because no drip edge was installed.

Any roof system should have drip edge, a common roofing component. This is the metal edge installed under the first rof of shingles on the slop of a roof. This lip of metal protects and directs rain water into the gutter.

New Roof On Top of Old Roof

Many roofing contractors will install a new roof over an old roof for one reason only: to save money. It is never the best option, structurally, for the roof or the home owner.

You should never install a new roof over your old roof. Most, if not all roofing material suppliers will void their warranty if their materials have been installed over an old roof.

Installing over an old roof can also cause waviness in appearance of the new shingles and roofing system.

Moisture, Rot, and Quick Aging

When the old roof is not removed, the old roof decking and sheathing is not inspected. The old roof decking may be affected by rot and deterioration, and can be a greater issue in the future. Rot and damp from the last roof may become trapped under the newest roof and increase the surface temperature, thus accelerating the aging process of the new system.

Pricing a new roof without walking on it is similar to asking a doctor to diagnos a patient without seeing him. Guesses and assumptions can be made, but nothing beats actually being there. 

Pricing can vary, and depends on the grade of materials chosen, the contractor, what type of building, the location and distance to travel, current labor rates and season of the year. 

We recommend homeowners get several quotes from quality contractors in their area. And remember, pricing is only one factor, which should be balanced against quality of workmanship and materials and guarantees.

And, keep in mind that for roofing materials, there are grades and different pricing per grade, along with a wide variety of shapes and styles. 

Clearly written quotes with pricing detail and line items indicate a roofing contractor who is preparing an thorough and accurate estimate. This list details a partial summary of items your estimate may include:

• The type of roof covering, manufacturer and color
• Materials to be included in the work, e.g., underlayment, ice dam protection membrane
• Scope of work to be done
• Removal or replacement of existing roof
• Flashing work, e.g., existing flashings to be replaced or re-used, adding new flashing, flashing metal type
• Ventilation work, e.g., adding new vents
• Who is responsible for repairing/replacing exterior landscape or interior finishes that are damaged during the course of the work
• Installation method
• Approximate starting and completion dates
• Payment procedures
• Length of warranty and what is covered, e.g., workmanship, water leakage

Look. The roofing industry is full of fly by night contractors providing below cost estimates and quotes that look GREAT. But, they are usually not insured, often perform sub-standard roofing work, and will not be around to stand behind their work should a leak or other quality issue arise. 

Don't hesitate to ask for clarification, for a detailed break down of the pricing. Any good contractor will be more than willing to help you understand his pricing.

There are as many warranty programs as there are roofing systems and manufacturers. 

However, generally there will be an asphaly shingle manufacturer's warranty, which usually covers defects in the shingle. This warranty will often range from 20 years to lifetime. In any case, be sure your roofing contractor gives you a certificate for your records.

Next, the roofing contractor should provide you with a warranty on his workmanship. This will normally cover materials installation and other related problems. This warranty usually details what items are covered and what will voide the warranty. Some roofing contractors offer one year, two year, or five year. There is no industry standard.

Asphalt shingles may be installed in cold weather. They do become more brittle in extremely cold temeratures. Breakage can be reduced or eliminated by storing shingles in a warmer area and bringing them out one bundle at a time for usage. Also, the self-sealing adhesive strips will not bond adequately in very low temperatures. This can be a problem in areas subject to high winds. This can be overcome with hand application of adhesive, which will hold the shingles in place until warmer weather.

If the shingle installation will not be affected by the wrinkling, then it can most likely be left alone. If, however, it is bad enough to stand up the shingles enough that they appear wavy as well, it may need to either be replaced or heavier weight shingles used.

Please make sure that any contract you sign with any contractor contains language making it clear who is liable for damages made to your property in the course of the work. 

Generally, you have two options:

1) Completely replace your roofing system, which would involve a full tear-off of your current roof.

2) Cover the current roof system, which means you only pay for installing a new roofing system.

We don't recommend re-roofing over a current roof system, as many issues remain in place from the current roof. Also, check with your local codes, as some building codes limit the number of times a roof system can be re-covered before a full replacement has to be done.

In most cases, roofing systems are designed to last in excess of 20 years. There are roofing systems like clay tile, slate, and some metal systems (copper) that can last longer.

The lifespan of roofing system depends on local climat, environmental conditions, building and roofing system design used, the quality of materials and workmanship used, and maintenance performed.

Many roofing system manufacturers have warranties that vary depending on grade of product. Be sure to understand the grade of shingle and roofing system being applied to your home, as warranties can vary widely.

Asphalt shingle material performance varies by quality, quantity and compatibility of asphalt fillers, reinforcements and surface granules. There are two kinds of asphalt shingles (based on the type of reinforcement mat used); fiberglass and organic. Fiberglass shingles are more fire- and moisture-resistant than organic shingles. Organic shingles have good wind resistance, high tear strength and can be installed in colder temperatures.

Asphalt shingles should be in compliance with American Society for Testing and Materials (ASTM) standards and applicable building codes. Fiberglass shingles should meet ASTM D 3462, "Standard Specification for Asphalt Shingles Made from Glass Felt and Surfaced with Mineral Granules," and organic shingles should meet ASTM D 225, "Standard Specification for Asphalt Shingles (Organic Felt) and Surfaced with Mineral Granules."

Consumers also should keep in mind a roofing warranty's length should not be the primary criterion in the selection of a roofing product or roof system because the warranty does not necessarily provide assurance of satisfactory roof system performance.

For asphalt shingles, NRCA recommends a single layer of No. 15 asphalt-saturated underlayment be used with roofs having slopes of 4:12 (18 degrees) or greater. For roof slopes between 3:12 (14 degrees) to 4:12 (18 degrees), NRCA recommends a minimum of two layers of No. 15 underlayment. If you are installing a heavier-weight shingle with a projected long service life, using No. 30 underlayment instead of No. 15 would be appropriate.

No. Two layers of underlayment are referred to as a "double-layer of underlayment" and there is a 19-inch overlap between layers. One layer of underlayment is called a "single-layer of underlayment" and there is 2 inches of overlap between layers. NRCA recommends a double-layer of underlayment for roof decks having slopes of 3:12 (14 degrees) up to 4:12 (18 degrees).

NRCA recommends galvanized steel or the equivalent corrosion-resistant roofing nails for asphalt shingle installation. Also, verify the governing building code requirements and what the shingle manufacturer recommends.

NRCA suggests the amount of attic ventilation be balanced between the eaves and ridge. The intent of a balanced ventilation system is to provide nearly equivalent amounts of ventilation area at the eave/soffit and at or near the ridge. For a balanced ventilation system to function properly, approximately one-half of the ventilation area must be at or near the ridge.

Proper attic ventilation is one of the least understood concepts in residential roofing. To learn more, read " Principles of Attic Ventilation" an article by Mark Graham, NRCA Associate Executive Director of Technical Services, that appeared in NRCA's magazine, Professional Roofing or see Technical Bulletin 98-2.

There are some manufacturers (and even model building codes) that will allow the application of asphalt shingle roof having that slope; however, NRCA does not recommend shingles on slopes less than 4:12 (18 degrees). Asphalt shingle roof systems are watershedding and rely on gravity and roof slope to effectively drain water off the roof.

There is no one roof system that is best for all applications. Keep in mind that even if you are using the best materials, your roof system still can be installed improperly and you could end up with a leaky roof. Good workmanship and proper attention to detail (e.g., flashing and drainage issues) are just as important as material selection. Also, maintenance plays an important role in roof system integrity and service life.

To assist you in your decision-making, homeowners should be informed of what is available. Please refer to the Roof System Types page to learn about the different low-slope roof systems.

Also, keep in mind low-slope roofing materials manufacturers may not offer material warranties to homeowners. The only warranty you most likely will be able to obtain is from the contractor. So it is critical you work with a professional roofing contractor and get a detailed, thorough proposal. Be sure to read the recommendations listed in Buying a new roof and getting your money's worth.

All too often, roof system problems are discovered after leaking or other serious damage occurs. Periodic (twice-a-year) inspections often can uncover cracked, warped or missing shingles; loose seams and deteriorated flashings; excessive surface granules accumulating in the gutters or downspouts; and other visible signs of roof system problems. Indoors, look for cracked paint, discolored plasterboard and peeling wallpaper as signs of damaged roof areas.

Not necessarily. Leaks can result from flashings that have come loose or a section of the roof system being damaged. A complete roof system failure, however, generally is irreversible and a result of improper installation or choice of materials or the roof system installation is inappropriate for the home or building.

Most work should not be done yourself. Professional roofing contractors are trained to safely and efficiently repair or replace roof systems. You can damage your roof system by using improper roofing techniques and severely injure yourself by falling off or through the roof.

Maintenance performed by home and building owners should be confined to inspecting roof systems during the fall and spring to check for cracked or curling shingles and cleaning gutters filled with dead leaves and other debris. If you must inspect your roof system yourself, use a firmly braced or tied-off ladder equipped with rubber safety feet. Wear rubber-soled shoes and stay on the ladder (and off the roof system), if possible.

Remove as much snow as possible, but call a professional roofing contractor if your roof is steep, the snow is deep or the ice is thick. NRCA does not recommend using ice picks or shovels (or any tool with sharp edges) because there is a chance of damaging roof coverings and flashings. NRCA also does not recommend hosing down a roof with water or use of a hot air gun. Electric heat cables generally have limited effectiveness.

Yes, and it is more probable for roofs with lower slopes, especially in valleys and upslope from curbs, chimneys and penetrations.

Generally, chemical melting compounds do not reduce the overall expected service life span of asphalt shingles. Staining may occur until all the residue is washed away. Calcium or magnesium chloride pellets are less harsh and stain less than sodium chloride.

Use a mild solution of chlorine bleach and water or mild detergent gently applied with a sponge or hand-held sprayer and rinse thoroughly. Do not use a power washer or high concentrations of bleach, and do not scrub the shingle surface. The Asphalt Roofing Manufacturers Association also offers cleaning recommendations.