The lifespan of an acrylic dome skylight has a lot to do with the quality of skylight that you buy. Some of the lower quality acrylic dome skylights will typically only last five to 10 years. If you get some of the nicer skylights in the industry, they could last as long as 20 years in some cases. You need to make sure that you get a high quality acrylic skylight because the surface can become brittle if you do not. The domes will also expand and contract so you need to make sure that they stay sealed.