Retractable Roofs and Domes in the Major Leagues

By 4Baseball Staff · November 5, 2026 · 10 min read

Which major-league parks have roofs, why clubs built them, how fixed domes differ from retractable roofs, and what the historical park factors show about how roofed parks play for hitters and pitchers.

Of the 30 major-league clubs, eight play in ballparks with a roof as of the 2025 season, according to this site's reference data for each park. Seven of them have retractable roofs: Rogers Centre in Toronto, Chase Field in Phoenix, T-Mobile Park in Seattle, Daikin Park in Houston, American Family Field in Milwaukee, loanDepot park in Miami and Globe Life Field in Arlington. The eighth, Tropicana Field in St. Petersburg, has a fixed dome, although the Rays played the 2025 season elsewhere after storm damage. The other 22 clubs play in the open air and take their chances with the weather.

The reasons for a roof are simple, and the choices are less so. A roof protects the schedule from rain, the fans from heat or cold, and the owners from empty seats on the nights when the forecast is bad. It also changes the field, the sound and the feel of a game, and it costs a great deal to build and operate. This article explains how roofed parks arrived, how the different kinds of roof work, which clubs use them, and what the historical record says about how the parks play. The dates below come from the historical home-game log, and the surface and capacity figures come from the site's own reference data, which can change after renovations.

Why a ballpark gets a roof

Baseball is a summer game played outdoors, and most of the sport's history assumes that the weather is part of the contest. Rain delays and postponements are the oldest of the sport's schedule problems. A postponed game has to be made up, often as part of a doubleheader, and a team that loses a home date also loses the ticket and concession revenue for it. Roofs solve that for the home team.

Heat is the other reason. In hot climates a midsummer game played in the late afternoon or evening can be punishing for both players and fans. In many roofed parks the building can also be cooled, which matters in Phoenix, Houston, Miami and Arlington, where summer temperatures are high for most of the season. Cold and rain are the issue in Toronto, Seattle and Milwaukee, which have the roofs, because their springs and autumns can be wet and chilly.

The costs are real. A roof adds construction expense and maintenance, and it adds an operating decision before every game: open or closed. A closed roof removes weather as a factor and changes the sound, which many players and fans find louder. It also removes sunlight and wind, which makes grass hard to grow and removes some of the character that open-air parks have. Every club that has built a roofed park has made a trade, and the many open-air parks built since 2000 suggest that most clubs have judged the trade not worth making.

The first domes

The first domed major-league stadium was the Astrodome in Houston, which opened in 1965. The historical record shows the Astros playing there from 1965 through 1999, and the first home game on April 12, 1965. Its roof was fixed, with translucent panels meant to let in sunlight so that natural grass could grow. The grass did not survive, and the club turned to a synthetic surface, which is where the name AstroTurf comes from. Grass versus artificial turf in baseball tells that story and what followed.

The 1970s and 1980s added more domes, often built to host football as well as baseball. The Seattle Mariners played in the Kingdome from 1977, with a concrete roof, and the Minnesota Twins in the Metrodome from 1982, whose roof was a fabric held up by air pressure. The Montreal Expos played from 1977 in Olympic Stadium, built for the 1976 Olympics. In Florida, the Tampa Bay Devil Rays opened their first season in 1998 in a fixed dome that had been built as a stadium in St. Petersburg in 1990, now known as Tropicana Field.

Those buildings shared a design philosophy. The roof was a lid, the field was artificial turf, and the baseball diamond was fitted into a multipurpose bowl. Players and fans did not always love them, and the domes of the 1960s through 1980s are largely gone: the Astros left the Astrodome after 1999, the Mariners left the Kingdome the same year, the Twins left the Metrodome after 2009, and the Expos left Montreal after 2004. The Astros, Mariners and Twins each moved to a new park in the same city, and they chose different designs: retractable roofs for the first two and open air for the third.

The retractable breakthrough

The idea of a roof that opens belongs to the late 1980s. Toronto's SkyDome, now Rogers Centre, opened in 1989 with a roof of large movable panels, and it is widely credited as the first major-league stadium with a fully retractable roof. The Blue Jays started the 1989 season at their old home, Exhibition Stadium, and the historical record shows them playing the first home game at the dome on June 5, 1989.

The idea spread through the 1990s and 2000s as clubs sought the benefits of a roof without surrendering open-air baseball when the weather was good. The table lists the retractable parks plus Tropicana Field, with the date of the first home game that the historical record shows at each, the surface in the site's reference data, and the capacity.

Several of these parks have changed names. Chase Field opened as Bank One Ballpark, Seattle's park was Safeco Field until 2019, Houston's has gone from Enron Field to Minute Maid Park to Daikin Park, Milwaukee's was Miller Park until 2021 and Miami's was Marlins Park until 2021. The Rays' first home game in the table is the club's first game in St. Petersburg, in 1998, not the opening of the building itself.

How the roofs work

The designs differ more than the word retractable suggests. All of them move large panels on tracks, but they use different layouts and different philosophies.

• Fully enclosing roofs. At Rogers Centre, Chase Field, Daikin Park, American Family Field, loanDepot park and Globe Life Field, a closed roof shuts out rain and wind. Whether the air inside is also cooled or heated differs from park to park, and the club's website is the place to check. Moving a roof of this size takes minutes, not seconds, so the decision is made before the game.
• An umbrella. The roof at T-Mobile Park is designed as a weather shield rather than a lid. It covers the seats and the field but leaves the sides of the building open, so it keeps off the rain without heating or cooling the air. Seattle's design reflects its climate, where the problem is rain and not heat.
• A fixed dome. Tropicana Field's roof does not move. The building is permanently enclosed, and its ground rules have to cover the catwalks and suspended structures that sit above the field.

The first rule of operating a retractable roof is that the home team decides whether it is open or closed, and the decision is made well in advance of the first pitch. The league's rules limit changes during a game, and those rules have been revised over the years, so they are worth checking against the current rulebook. A game that begins under an open roof may be closed if the weather turns bad, as long as the rules allow it.

The roof as a ground rule

A roof is also part of the field of play, and every roofed park has a ground rule about what happens when a batted ball strikes it. In an open-air park, a fly ball can go as high as it likes. In a dome, a high pop-up can hit the ceiling, a catwalk or a light. Depending on the park and the point of contact, a ball that strikes a fixed object over fair territory may be live, dead, or a catch if a fielder takes it on the way down, and umpires and clubs agree on the details before the series. The Official Baseball Rules allow parks to set their own ground rules for these situations, and visiting players should learn them. Fixed domes with suspended catwalks tend to have the longest lists.

The practical advice for a fan is to read the ground rules posted at the park, and for a player to ask the crew chief before the game.

What the park factors show

If roofs changed how the ball flew, you would see it in the historical park factors. The batting park factor, BPF, is a three-year figure scaled so that 100 is neutral, with higher numbers favoring hitters. The table gives the average across the seasons the historical record lists for each park name, and the range.

The table makes two points. The first is that a roof does not decide how a park plays. Arizona's park has been the most hitter-friendly of those listed, while Seattle's, with a roof of a different kind, has been the most pitcher-friendly. The second is that the numbers move: the same park can read 90 in one season and 106 in another, since the factor is influenced by the club's own players, pitchers and weather. The measure compares a club's home and road results, which cancels most of its own talent but not all of it.

For the best explanation of why the numbers differ, look at the dimensions, the altitude, the humidity and the wind, which the roof leaves to the building's shape and climate. Phoenix sits at a higher elevation than most major-league cities and has dry air, which helps the ball carry, and the building's shape and altitude do not change when the roof closes. Seattle's open sides let in cool, damp air. These are the same variables that why ballpark dimensions are all different discusses for every kind of park.

When a roof is not enough

A roof protects against rain but not against everything. In 2017 the flooding from Hurricane Harvey kept the Astros from playing at home, and a series was moved to Tropicana Field instead. In October 2024 Hurricane Milton damaged the roof of Tropicana Field itself, and the Rays played the 2025 season at George M. Steinbrenner Field in Tampa, a smaller park that normally hosts spring training. The site's reference data notes both the damage and the move.

The episodes show that a roof is a tool against ordinary weather, and a very large structure can fail in extreme weather. They also show how much a club depends on its building. The Rays' listed capacity at Tropicana Field is 25,025, a small figure by major-league standards, and a club in a smaller park needs different economics.

The cost and the future

Roofs are expensive, and the cost helps explain why more clubs have not built them. How a ballpark is built and financed explains the economics, including the role of public money. The trend since the retro era, which began with Camden Yards and the retro ballpark era, has been toward open-air parks that look like old ones. The Twins left a dome for the open-air Target Field, and most new parks have not had roofs. The recent exceptions are in hot or wet climates: Miami in 2012 and Arlington in 2020.

Naming rights add a wrinkle. Many roofed parks have carried several names, and naming rights and the business of ballpark names explains why a stadium's sign can change every decade or so while the building stays the same.

Common questions

Which major-league parks have a roof? According to the site's reference data as of the 2025 season: Rogers Centre, Chase Field, T-Mobile Park, Daikin Park, American Family Field, loanDepot park and Globe Life Field have retractable roofs, and Tropicana Field has a fixed dome.

Which was the first domed stadium? The Astrodome, which opened in 1965 in Houston. The first stadium with a fully retractable roof was Toronto's SkyDome, now Rogers Centre, in 1989.

Does a roof mean no rain delays? For fully enclosing parks, a closed roof removes rain from the game. T-Mobile Park's roof covers the field, though its open sides mean wind and cold still get in. A roof cannot protect against a hurricane, a power failure or other emergencies.

Do roofed parks favor hitters? Not as a group. The historical park factors range from about 94 in Seattle to about 104 in Phoenix, so the answer depends on the park.

Is the grass real? In the site's reference data, the surface at T-Mobile Park, Daikin Park and American Family Field is natural grass, and the surface at the other roofed parks is artificial turf.

Where to go next

For the surface question, read grass versus artificial turf in baseball. For how the numbers are read, how to read a baseball box score explains the scoring shorthand. For a different view of the same cities, the ballparks and fans topic page collects current coverage, and the Rogers Centre page and Chase Field page keep the reference data for two of the parks above.