The answer to 'how long does flat roof last' is that a properly installed and well-maintained flat roof can last between 10 to 20 years, or even longer in some cases. The lifespan of a flat roof depends on factors like the roofing material used, the quality of installation, and the climate and weather conditions the roof is exposed to.
Flat roofs made from materials like EPDM (rubber), TPO, or modified bitumen tend to have a longer lifespan compared to built-up roofs or asphalt roofs. Proper maintenance, such as regular inspections, prompt repairs, and keeping the roof clear of debris, can also significantly extend the roof's lifespan.