The answer to a flat roof that is worn out is that it likely needs to be replaced. Flat roofs have a limited lifespan of around 10-20 years, and over time the roofing materials can become cracked, worn, or damaged from weathering and age. Common signs of a worn-out flat roof include leaks, ponding water, crumbling or missing materials, and visible deterioration.
While some minor repairs may be possible for a flat roof in relatively good condition, a worn-out roof will typically require a full roof replacement. This is a job best handled by professional roofing contractors, as it involves properly removing the old roofing, inspecting and repairing the underlying roof structure, and installing a new durable roofing system. Attempting a DIY flat roof replacement is generally not recommended, as it requires specialized knowledge and tools to ensure a proper, long-lasting installation.