As a contractor (i.e. I have my own company and pay salary to myself) for about 12+ years, IMHO, the additional cost as a full time employee (FTE) to an employer usually is around additional 20 to 40% of a FTE basic salary.
The additional cost can be as follows
CPP + EI + Vacation + Extended Health Insurance + Bonus + Others (Cell phone, laptop, additional benefits, like health spending account, or activity account, or transportation reimbursement, or employee discount, such as discount in mortgage if you work in a credit union)