Roofing costs can vary greatly depending on the condition of the roof deck, the number of layers of roofing being removed, the number of stories of the project, and the steepness of the roof. Roofing is hard and dangerous work and most of the materials in residential roofing are petroleum-based and prices are constantly going up. Like most home improvement projects, prices can vary based upon the quality and type of materials, the contractor you select and the time of year the project is scheduled. Contractors with the most experience, proper licensing, insurance, and manufactures certifications are typically more expensive than less experienced qualified roofers.