Many factors impact costs when repairing or replacing your roof. You need to take into consideration the area of the roof needing repair, the slant of the roof, difficulty of working on the roof and the average rates for roofing contractors in your neighborhood. You can estimate roofing costs once you have all this information. Typically, you can determine the cost of materials by multiplying the roof's square footage by the cost per square foot of material.
Identify the areas you need to roof. Generally, a roof is half again the size of a home. So, if your home is 1,500 square feet, you can estimate your roof is around 2,250 square feet.
Determine the pitch in your roof. Most standard ranch-style homes have a gable roof. This is the least expensive and easiest roof to replace. The steeper your roof is, the more expensive it is to replace because the contractor needs to use specialized equipment like harnesses to access the roof top.
Evaluate the difficulty of replacing your roof. Again, certain styles of roofs are easier and cheaper to replace. If you use solar panels or have multiple skylights in your roof, this affects the costs of materials and labor.
Find out if your contractor wants to remove the existing roof. This may be necessary to fix your roof, but it won't be cheap. You may need to remove your whole roof, depending on the condition of the roof and whether you want to change the roofing material from asphalt shingles to Spanish tile, for example.
Research the going rate for roofing work in your neighborhood. Costs can vary widely between individual contractors and companies.
Determine the material you are going to use on your roof. Materials such as asphalt, wood, metal and solar energy panels vary in price. If you decide to use materials such as Spanish terracotta tiling, you'll need to estimate the extra costs into your budget for a contractor that specializes in laying this type of roofing.
Consult with several roofing contractors before choosing one to replace an existing roof.