Fourplex addition in Ontario Canada

[Kelly Mae]

I am considering building up on my fourplex. 2 additional units. The cost would be about 500k about $250k cheaper than it would be to buy another duplex property in my area. I will likely get approval based on my zoning. The footings support an addition. I would be taking equity out of the property to build. I am debating the move and would like to know the downsides I might be overlooking. Currently the building runs well, good tenants who are below market rent but there is harmony and dependable cash flow. Thoughts?