The cost of affordable housing prompts many people to consider renting out a suite in their basement to help with mortgage payments.  In some cases these are legal suites and in many cases they are not.  If the tenant is a family member that is not a problem but if it is a complete stranger you may be violating local by-laws.  If it is a legal suite then the lending institutions will take that into account when calculating the cost of your monthly income and how much of a mortgage they will give you.  

For a good article on this subject see

http://www.rew.ca/news/how-to-maximize-income-from-a-mortgage-helper-suite-1.2153935?rew.ca/news=rew.ca/news