The half-a-billion dollar retractable roof on BC Place Stadium will not be able to close in the rain when it is completed next September, CBC News has learned.

Howard Crosley, the general manager of BC Place, said the operators will have to make a decision to open or close the roof based on the weather reports, but they won't necessarily be able to close it if they make the wrong call.

"The way the roof actually works, it's a gathering material that comes into the centre and because of that, if it's raining or high winds, we won't be able to open or close it," he said.

When it is finished, the roof will be the largest cable-supported retractable roof in the world and will take about 20 minutes to open and close, according to officials. But fans will stay dry no matter what because the 55,000 seats in the stadium are covered by a fixed section of the fabric roof, Crosley said.

BC Place Stadium is run by the B.C. Pavilion Corporation, which is owned by the provincial government, and overseen by the Minister of Tourism.

The $565 million renovation to the stadium will be completed in the fall of 2011, well before the Grey Cup, which Vancouver is scheduled to stage Nov. 27, officials announced Monday.

The stadium will be the home field of the CFL's BC Lions and the Vancouver Whitecaps of Major League Soccer. Both teams will start their season at other locations but expect to end them at BC Place.

Both North American football and soccer are traditionally played in all weather conditions.