Interior paint has a lifespan of between seven and ten years compared to the average of seven years for exterior paint. Its lifespan is considerably longer when exposed to UV light, temperature fluctuations, humidity, and ozone. Interior paint may need to be redone more frequently than exterior because those factors can cause it to fade quicker. Avoid letting objects made of wood or metal touch the wall where you are applying your new paint. They may damage your painted surface over time.