The answer to 'when to replace flat roof' is that flat roofs typically need to be replaced every 10-20 years, depending on the materials and climate. Flat roofs are more susceptible to leaks and damage over time compared to sloped roofs, so regular inspections and maintenance are crucial. Signs it's time to replace a flat roof include visible cracks, blisters, or pooling water that doesn't drain properly.
Replacing a flat roof is an important investment to protect your home from water damage and ensure your roof lasts as long as possible. It's best to have a professional roofing contractor inspect your flat roof annually and provide recommendations on when to consider a full replacement.