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Selecting a contractor

The price of a new roof varies widely depending on materials selected, contractor doing the work, size of the home, location of the home, local labor rates and time of year. To get a good idea of price, get three or four proposals from reputable contractors in your area. Keep in mind price is only one factor, and it must be balanced with the quality of the materials and workmanship. For each roofing material, there are different grades and corresponding prices. There also are a variety of styles and shapes. You need to look at the full product range and make a choice based on your budget and needs.

Clearly written, detailed proposals are a good sign the contractor is being thorough and has prepared an accurate estimate. Following is a partial list of items your estimate or proposal should include:

  • The type of roof covering, manufacturer and color
  • Materials to be included in the work
  • Scope of work
  • Removal or replacement of existing roof
  • Flashing work
  • Ventilation work
  • Who is responsible for repairing/replacing exterior landscape or interior finishes that are damaged during the course of work
  • Installation method
  • Approximate starting and completion dates
  • Payment procedures
  • Length of warranty and what is covered

There are different warranties you will come across during your roofing project. First, there will be the manufacturer’s warranty. In general, this warranty covers defects in the manufacture of the roof covering material. The period of coverage can range from 20 years to a lifetime. Once the project is complete, be sure the contractor provides you with a certificate for your records. Second, the roofing contractor will provide you with a workmanship warranty. Typically, this will cover installation and related issues. The warranty should contain what items are covered and what will void them. Many contractors offer one or two years of coverage; however, there is no industry standard.


There are differing opinions concerning the amount of attic ventilation necessary. Based on current research, the strongest case for ventilating asphalt shingle roof assemblies with outside air exists for homes located in cold climates and where snow accumulations persist on roofs for extended periods of time. Under those conditions, ventilation has been shown to be a valuable strategy for removing excess moisture from attics, preventing condensation that can damage roof sheathing and preventing ice dam formation.

In addition, ventilation with outside air reduces average attic air temperatures in summer. Research has not verified a significant effect of attic ventilation on the average roof surface temperature. In fact, research results indicate ventilation has less effect on average roof surface temperature than the direction a roof faces or roofing material color.

Asphalt shingle manufacturers’ warranties may make coverage conditional on meeting minimum ventilation requirements. You should consult manufacturers for specific ventilation requirements when selecting an asphalt shingle product.

Project problems

There are no specific temperature guidelines regarding when it is too cold to install asphalt shingles. Asphalt shingles become brittle in cold temperatures, but breakage can be minimized or eliminated if shingles are stored in a warm area and loaded onto the roof a few bundles at a time. Another concern is the self-sealing strips will not seal or bond sufficiently in cold temperatures. Hand-tabbing (applying quarter-size dabs of adhesive to the underside of shingles) is recommended if a home is in an area prone to high winds. This will help prevent the shingles from blowing off the roof until warmer weather arrives and the sealing strips can set properly.

If the wrinkling isn’t severe enough to affect shingle installation, the underlayment probably can remain in place. The effects of wrinkling will be minimized by using heavier-weight shingles. An underlayment can remain in place without a roof covering for some length of time. Time is not the critical issue; the condition of the underlayment is what’s important.

Before you sign a contract, make sure it contains language addressing who is responsible for any damage that occurs as a result of the roofing work. All items of concern and work to be done should be included in the contract.


You have two basic options: You can choose a complete replacement of your roof, which involves tearing off your existing roof, or you can re-cover the existing roof, which involves installing a new roof directly on top of the existing roof. However, in many instances, building code requirements allow no more than one roof re-cover before a complete replacement is necessary.

Most new roofs are designed to provide useful service for about 20 years. Some roof types, such as slate, clay tile and certain metals, can last longer. Actual life span is determined by several factors, including local climatic and environmental conditions, proper design, material quality and suitability, proper application and adequate maintenance.

For asphalt shingles, NRCA recommends a single layer of No. 15 asphalt-saturated underlayment be used with roofs having slopes of 18 degrees or greater. For roof slopes between 14 and 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 has 2 inches of overlap between layers. NRCA recommends a double layer of underlayment for roof slopes of 14 to 18 degrees.

NRCA recommends galvanized steel or the equivalent corrosion-resistant roofing nails for asphalt shingle installation. You should 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, about 50% of the ventilation area must be at or near the ridge.

There are some manufacturers (and even model building codes) that allow the application of asphalt shingles on a roof with that slope; however, NRCA does not recommend shingles on slopes less than 18 degrees. Asphalt shingle roofs rely on gravity and roof slope to effectively drain water.

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


All too often, problems are discovered after leaking or other serious damage occurs. Biannual 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 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 being damaged. But a complete roof system failure generally is irreversible and a result of improper installation or choice of materials or the 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 roofs. You can damage your roof by using improper roofing techniques and severely injure yourself by falling off or through the roof. If you perform maintenance, it should be confined to inspecting your roof 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, 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) 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 using 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 of asphalt shingles. However, staining may occur until all the residue is washed away. Calcium or magnesium chloride pellets are less harsh and stain less than sodium chloride.


The Insurance Institute for Business & Home Safety offers its FORTIFIED Home program for homeowners to significantly improve their homes’ resistances to damage from specific regional natural hazards. The program provides uniform, voluntary sets of standards that will help bring elements of existing homes up to current code requirements or, in some cases, exceed code requirements. Homeowners can apply for a FORTIFIED Home designation on IBHS’ website,


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