The answer to 'when to replace soffit' is that you should typically replace your home's soffit when it shows signs of significant wear, damage, or deterioration. Soffit is the material that covers the underside of your roof's overhanging eaves, and it plays an important role in ventilating your attic and protecting your home's exterior.
Common signs that it's time to replace your soffit include cracking, warping, rotting, or sagging of the material. You may also notice issues like pest infestations, water damage, or poor ventilation, which can indicate the soffit needs to be replaced. As a general guideline, most soffits last 20-30 years with proper maintenance, but factors like climate and material type can impact the lifespan.