But because both typically are covered with low-maintenance aluminum, performance is similar. You'll also pay about the same for high-quality skylights made of either material. Add another 15 to 25 percent to the cost for a ventilating model. Building codes require either tempered or laminated glass. Both types are designed to stand up to snow loads and provide protection against falling objects.
Tempered glass breaks into small pieces, rather than large shards, if damaged.
Laminated glass, which is fused with a thin layer of plastic, stays in place for added safety if broken. It's also better at keeping out sound and is slightly more energy efficient, though also slightly more expensive. Many skylight manufacturers offer an outside pane of tempered glass with an inside panel of laminated glass. Skylights are also available with plastic glazings. Plastic is less energy efficient than glass, but it costs less and can be formed into domes and curved skylights.