I have heard that an enclosure SHOULD be at least 16 times larger then the tortoise itself. Also make sure you have the neccesities to properly maintain a tortoise.
Five years old is much too big to be an indoor tortoise. I realize you live in Canada, but you're going to have to figure out a way to set this tortoise up either in a whole room, the basement, or garage (when the weather is too cold for outside). He'll drive you crazy trying to dig through the walls to get out. Its just not fair to the tortoise to build him a pen, unless its the size of a bedroom.
until its 10 years old.. then its just not fair... they do best outside. Real sunshine... fresh grass...
I understand the want... but if you lived in a apt.. you wouldnt house a horse inside...
they arent odorless....they are destructive...