How Much Does a Tar & Gravel Roof Cost?

When a home with a tar and gravel roof starts experiencing roof leaks and related problems, it may be time to replace the entire roof: They're usually beyond repair at this point. Certain roof contractors recommend a complete replacement of the roof. This is to prevent homeowners from sinking large sums of money into temporary fixes, only to end up replacing the roof anyway in a few years because the patched areas didn't hold.

Tar and gravel roofs are also known as built-up roofs. This traditional type of roofing is built up from at least three layers of a waterproof material, alternating with hot tar. The top layer is covered with gravel-sized smooth stones. Tar paper was originally used, although roofers now often use newer, advanced materials such as a fiberglass membrane. Tar and gravel is the best type of roof for flat-roofed homes. When the roof has no slope, water pools after it rains and causes issues, especially if the roof is damaged or old. Drainage can be a problem as well, creating water damage and leaks into the home's interior. Flat roof replacements usually have a 10- to 20-year warranty on the work, although many last as long as 25 years.

Roofing contractors may quote pricing in terms of materials and labor "per square," which is 100 square feet. The average is $250 to $350 per square, or about $2.50 to $3.50 per square foot. Part of the cost of replacing a tar and gravel roof is the removal of the old roof material. The combined cost of stripping the old material and replacing it with new tar and gravel is estimated to cost about $4 to $6 per square foot. The cost of installing the roof should include materials delivery, the underlayment, any flashing needed and fasteners.

Based on the calculator provided on Homewyse.com, which includes the costs for materials and installation, the estimated per-square-foot price for a 1,200-square-foot home in Southern California was $3.10 for a basic level roof, $4.33 for a better quality and $5.75 per square foot for a roof with the highest-quality materials.

Installation is best performed by a skilled, knowledgeable roofing contractor, as a less-experienced contractor or handyman may make costly mistakes. Costs may change depending on the size of the home's roof, the region the house is in and seasonal rates. The difficulty of the installation matters, and complex roof layouts or shapes may increase material and installation costs from 3.5 percent to 11 percent. The cost depends on the materials' level of quality. More expensive roofs have thicker materials of a higher quality that offer longer service. Additionally, installation represents a substantial component of the cost. A final estimate of the costs is prepared after a roofing contractor has inspected the roof on-site.