Retractable roof

Stadium retractable roofs are generally used in locales where inclement weather, extreme heat, or extreme cold are prevalent during the respective sports seasons, in order to allow for playing of traditionally outdoor sports in more favorable conditions, as well as the comfort of spectators watching games played in such weather.

The first retractable roof sports venue was the now-demolished Civic Arena in Pittsburgh, Pennsylvania, United States.

[4] The roof enables matches to continue during rain, extreme heat, and in the presence of smoke from bushfires in surrounding regions.

Although each retractable roof differs in these aspects, the roof of T-Mobile Park[6] is unique in that it is the only one in North America that does not form a climate-controlled enclosure when in the extended position; rather, it acts as an "umbrella" to cover the playing field and spectator areas during inclement weather, with no side walls enclosing the stadium.

In North American major sports leagues, specific rules exist governing the movement of retractable roofs before and during gameplay.

Depending on the stadium, weather or gameplay conditions, and the judgment of the officials, play may or may not continue until the roof is fully closed.

Open roofs are typically seen at smaller athletic venues such as country clubs and universities, and also in the construction of commercial greenhouses and garden centres for climate control purposes.