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 conditions. Flat roofs are more prone to leaks and damage over time compared to sloped roofs, so homeowners should closely monitor their flat roof and consider replacement when it shows significant wear, damage, or leaks.
Some key signs it's time to replace a flat roof include visible cracks, blisters, or pooling water that doesn't drain properly. Older flat roofs made of materials like asphalt or tar may also start to deteriorate and need replacement, even if there are no obvious leaks yet. Calling a professional roofing contractor to inspect the roof and provide recommendations is the best way to determine if replacement is needed.