Seasonal rooms come in many forms. Here are the basic types to consider if you want to add a sunroom. Deciding on the best location to add a sunroom is the first step when planning a glass or screen addition. Consider the typical weather where you live and the direction the sunroom windows will. Understanding the components of a seasonal room will help you select the type of space you want. Vinyl is the most popular material used for the supports of a sunroom. It costs the least, requires. Sunrooms, four-season rooms, and greenhouses are walled with glass and roofed with glass or polycarbonate (a tough, transparent thermoplastic). A glass roof is considerably more expensive but provides the most clarity. Look for the U-value of the glass or polycarbonate; this is a measure of how much heat the material conducts. The lower the. If you can't build your sunroom in the location that will keep it the most comfortable, or you want more hours to enjoy your all-season room, consider these options: 1. Add operative skylights to act as heat dumps when the room gets too warm. 2. Intersperse prefabricated insulating roof panels among the glass roof panels. Look for R-factors of R-16.