Admitted to the Union in the year 1818, Illinois is the 21st state of the United States. It is home to roughly 12,812,508 people, and ranks as the 25th largest state, occupying an area of 149,995 km². Lying in the middle of the Atlantic Ocean and the Continental Divide, the state typically sees humid continental climate. Its climate is characterized by hot and humid summers and cold, near-freezing winters. The southern tip, however, which lies 500 miles away from the Gulf of Mexico, sees humid subtropical climate, and has relatively moderate winters. Thunderstorm activity in the state is on the higher side - Illinois sees over 50 days of thunderstorm activity annually. Tornadoes are fairly common here - the state sees an average of 54 tornadoes every year. Illinois is known for being the victim of the deadliest tornado in the United States - the Tri-State Tornado, which killed 613 people in Illinois (and another 82 in other states).
Illinois’ harsh climatic situation warrants the use of materials and designs that are capable of handling any type of extreme - be it hold or cold, or rainy or cyclonic. This puts both gable roofs and flat roofs at the top of the preference list for homeowners and commercial property owners alike. Each has their own unique area of strength - while gable roofs offer a certain level of aesthetic appeal which sits well with homeowners, flat roofs are key in cutting down the element of extra friction. It is perhaps for this reason that they are common in residential areas as well. Combination roofs are also in use, these pull out 2 or more materials and/or designs to create a single custom roof - used mostly in unique situations. In recent years, eco-friendly options have become popular - like roofs that double as solar panels or harness wind power.