The Advantages and Disadvantages of Salvaging an Older Tar and Gravel Roof

Tar and Gravel Roofing

• A tar and gravel roof consists of layers of asphalt and tar paper that are covered with gravel. The gravel acts as a ballast, holding the tar paper in place and preventing extreme climatic conditions from damaging the material beneath. Some of the gravel becomes embedded within the hot asphalt, while the rest remains loose. As the roof ages, wind may blow the gravel off some portions of the roof, leaving the tar beneath vulnerable to heat and cold, which can cause cracks. These cracks must be patched and then covered with new gravel, but this may be a temporary repair that you’ll have to do more than once.

Durability

• A properly installed tar and gravel roof can last 20 years or more with the right care. A tar and gravel roof will break down over time, though. The asphalt can crack as gravel is blown away, and it's exposed to the elements. Patching is a fast and easy way to repair minor damage and can prolong the life of the roof. But because the patched areas have been exposed to moisture, you’ll have to keep an eye on the repairs to ensure that they hold up under extreme weather conditions. Leaks or cracks in a salvaged roof may have to be repaired several times, and the repair work may even become a yearly project to prevent damage from future leaks.

Cost

• The biggest advantage of salvaging an old tar and gravel roof is cost. Patching an older roof requires only the purchase of liquid roofing patch and gravel. You may choose to have a qualified roofer do the work. This adds to the repair cost, but when compared with replacing the roof, patching costs significantly less. Some tar and gravel roofs, however, are simply too old or too damaged to repair. If there are several large leaks, the roof should be replaced.

Number of Layers

• An older roof may have several layers of tar and gravel. This can be problematic, because tar and gravel roofing cannot hold up after too many layers. When an old tar and gravel roof is repaired, loose gravel is swept off the surface, and a new layer of tar paper and hot asphalt is applied. But the older layers may still have some loose gravel, which can cause cracks and punctures in the new layer. Holes in the membrane can cause the layers to separate. The separated layers expand in the heat and then blister. In cold weather, the blisters crack, allowing water to enter. This will undo your repair work. According to the Eureka Modern website, many roofing contractors advise against salvaging an older tar and gravel roof for this reason.