Tear-offs and overlays are two types of roof replacement methods. In a tear-off, the contractor removes existing roof materials and replaces them with new ones. Meanwhile, an overlay keeps the current roof as is and simply lays the new materials on top.
When tearing off, you’ll be able to identify and solve any underlying issues that exist under the current roofing layer. However, it is more expensive due to the increased labor.
Overlays are much cheaper and faster since the contractor doesn’t have to remove the existing roof materials. But the old roof might not be able to handle the extra weight of the new one on top and could become compromised.