Cedar: untreated and a wood that is easy to find. There are different varieties (red, white, etc.) which will be more or less adapted to your budget.
Composite (recycled plastic) boards: easy to maintain and very durable because they are water-resistant. However, they should not be used for the structure of the terrace.
Hemlock: strong and durable wood. By combining cedar and hemlock, you will have a durable and ecological terrace.
Prefer natural wood to treated wood. Its environmental impact is lower and it is a more durable wood.
Avoid using tropical woods; their use contributes to massive deforestation.
In Canada, you will find a wide variety of local woods.
For more advice on building or landscaping your deck or balcony, visit the eco home site.