Connecting two buildings depends on whether you're bridging them above ground, at ground level, or below grade. Skyways and elevated walkways are common in downtown cores like Toronto's PATH system or Minneapolis, but they require structural analysis to ensure both buildings can support the connection points and wind loads. You're looking at engineering costs starting around $150,000 CAD for basic feasibility studies alone, with total project costs ranging from $500,000 to several million depending on span distance and finishes. Ground-level connectors are simpler but eat up land between buildings. You'll need setback variances if the gap crosses property lines, plus accessibility compliance under Ontario Building Code or equivalent provincial standards. Underground tunnels cost more per linear metre due to excavation, waterproofing, and ventilation requirements, but they preserve street-level aesthetics and avoid airspace complications. Key approval hurdles include fire separation requirements, egress path analysis, and ensuring the connection doesn't create a single building classification that triggers different code requirements. In Ottawa, you'd work with the city's Building Code Services and potentially Heritage Planning if either structure has designated status. Practical considerations: - Ownership structure matters. If buildings have different owners, you need easement agreements and shared maintenance terms before breaking ground. - HVAC integration often gets overlooked. Connecting buildings can create pressure differentials that affect heating efficiency. - Insurance and fire safety classifications may change, impacting premiums and sprinkler system requirements. From a project management standpoint, budget 12-18 months minimum from concept to occupancy for above-grade connections. Underground or complex heritage situations can push that to 24+ months. Hire a structural engineer and code consultant before architects start drawing, because feasibility kills more connector projects than budget does. The engineering determines whether your vision is physically possible, then municipal approvals determine whether it's legally possible.