You will need a Building Permit if:
• Your deck will be higher than 0.6m (approximately two feet) above grade at any point.
• You are building a covered deck such as an enclosed sundeck, a deck with open rafters or a gazebo (this is considered an addition and may require a Development Permit).
For More info: click the link below:
https://www.calgary.ca/development/home-building/decks.html