If you need to do renovations to your home to accommodate a legal basement, there are some costs involved to get your space up to code. You will have to purchase a building permit to do any construction. You can also expect to pay renovation costs such as material and labour to get your home move-in ready. With the average cost of $5 to $30 a square foot, homeowners can expect to spend up to $30,000 to make the necessary renovations. However, you will quickly get a return on your investment once you begin collecting rent.