Verify an Estimate Before the Roofing Work Begins

Roofing Contractor Quotes or Estimates

The contractor should come to the job site and do a written estimate. The roofer will measure the roof area and determine how much material will be required to complete the job. The contractor will likely refer to the roof area as a certain number of squares. A square is 100 square feet of roof surface or an area equal to a 10 foot by 10 foot square. The roofer will add a percentage for material wasted (10 to 15% is normal for most residential roofs).

The roofer will also determine the pitch or angle of the roof. The pitch is usually referred to in ratio form. "X" number of feet of rise for every 12 feet of length. So, a roof that rises 4 feet in a 12 foot distance would be referred to as having a "4 in 12" pitch. This ratio is important for several reasons. Most standard shingles, wooden shakes, metal sheeting, or other residential roofing material must only be applied to roofs with a pitch of "3 in 12" or higher. If the material is applied to a lower slope then the warranty will usually be void and the roof will be more likely to leak and weather faster.

As stated above, most residential roofs will have a pitch steeper than "3 in 12" and therefore can receive a wider range of roofing material. Typically the roofer will remove any existing shingles, although many local building codes will allow as many as two layers of shingles to be applied to the roof. Older homes will sometimes have more than two layers already applied. In these cases shingles must be removed before additional shingles can be applied.

The contractor will also recommend appropriate roofing material. He or she might have samples or can send you to a showroom or supply house where you can view the material he believes best needs your particular needs.

Most roofers' quotes will also include the installation of new drip edge which is the metal trim which is applied along the outside edge of the roof. If the existing shingles are removed, then roofing felt is also generally included in the bid. Roofing felt is a building material which comes in rolls, which are 3 feet wide. Felt is generally manufactured in two residential weights - 15 and 30 pound weights. The 15# felt is much thinner and tears more easily. If the felt will be exposed to the weather for any length of time, most roofers will prefer to apply the 30# felt. A roll of 15# felt will cover 400 square feet, while a roll of 30# felt will only cover 200 square feet. The felt serves as an underlayment.

Roofing contractors should also install pipe boots to any plumbing, electrical, or HVAC pipes which protrude through the roof. On new construction the boots are routinely provided by the general contractor or the mechanical contractor whose pipe needs the boot. It is usually best, however to have the roofing contractor to complete the installation. When a new roof is installed on an existing home, the roofer will generally supply the boots.

When a roofing contractor comes to the site to complete his estimate, he should also examine the roof to determine is there is adequate roof ventilation. Older homes in particular, often do not have sufficient ventilation. Some roofs will have soffit and ridge vents. Some homes have gable ventilation and still others will have box vents which are mounted on the roof surface. Some of these vents might also have fans which will turn on when the attic temperature becomes too high. A common sign of a roof with inadequate ventilation is when shingles are curled up and no longer lay flat on top of each other.