Adding a second storey is one of the most effective ways Melbourne homeowners expand their living space without extending their footprint — but it’s also a project where the existing structure, not just the new addition, determines what’s actually achievable. Before any design work on the new level, a structural engineer needs to understand whether the existing home can support it.

• 26 August 2026
• Komal Chauhan

Why the Existing Structure Comes First

A second storey addition adds substantial new load to a building that was originally designed — and its footings sized — for a single-storey structure. The first question a structural engineer needs to answer isn’t “what does the new level look like,” but “can the existing footings, walls and framing support the load this addition will add.”

This assessment often shapes the design more than homeowners expect — the existing structure’s capacity can determine where load-bearing walls need to align between floors, what additional strengthening is required at ground level, and in some cases, whether footing upgrades are needed before construction can proceed.

What’s Assessed Before Design Begins

• Existing footing type and condition — older Melbourne homes often have footings that need assessment or upgrading to support additional load
• Ground floor wall alignment — new upper-level load-bearing walls generally need to align with load-bearing walls or additional support below, which affects both structural design and floor plan layout
• Existing roof and floor framing — determining what can be reused, modified, or needs replacement as part of the addition
• Site and soil conditions — relevant to whether footing upgrades, if needed, are straightforward or more involved

Why This Affects Design, Not Just Engineering Sign-Off

Because upper and lower floor structural elements need to work together, the structural engineer’s input often needs to happen alongside architectural design, not after it’s finalised. A floor plan designed without structural input risks needing significant rework once it becomes clear where support actually needs to align.

Temporary Works During Construction

Second storey additions typically require some level of temporary support to the existing structure during construction — supporting the roof while it’s removed, and managing the building’s stability while new structural elements are installed. This temporary works planning is a meaningful part of the structural engineer’s scope on these projects, not an afterthought handled solely by the builder.

Getting an Early Feasibility Assessment

For homeowners considering a second storey addition, an early structural assessment can clarify whether the project is straightforward or whether existing footing or framing limitations will add cost and complexity. This is valuable information before committing to an architectural design, since it shapes what’s realistically achievable on the existing structure.

EMS Engineering Consultancy assesses existing structures for second storey additions across Melbourne, working with homeowners and builders from early feasibility through to permit-ready structural documentation.