Start with depth. The district's post-war lots are often 120 feet or deeper, which opens the door to a fourplex at the front and a garden suite at the back. To keep that option alive, the fire access path and the servicing for five units need to be planned from the first sketch.
Second, confirm the unit cap. The district is outside the approved sixplex areas, so four units in the main building is the maximum. If someone has drawn six units on your lot, stop before spending more and get the zoning confirmed in writing.
Third, check the ravines. Lots along the Humber River and Etobicoke Creek may be subject to ravine protection and conservation authority regulation. The regulated limit can sit well inside the lot line, so it needs to be mapped before the building is placed.
Fourth, plan for the lake. Mimico, New Toronto, Long Branch and Humber Bay lots within 500 metres of Lake Ontario need corrosion-resistant fasteners and careful flashing. The extra cost is small and avoids rust and leaks down the road.
Finally, compare conversion and rebuild. Many local bungalows are solid, and a basement unit plus a rear addition or top-up can be good value. Where the foundation is weak or the house is small, a new fourplex usually makes better use of a deep lot.
