Renovate, add on, or rebuild?

Define the non-negotiables

List the outcomes that must be achieved: a different layout, more space, better comfort, improved accessibility or a closer connection to the outdoors. Identify what the existing property already does well. Be explicit about emotional value, location and elements you want to preserve.

Build three comparable options

A renovation can work within the existing building; an addition can increase space while retaining part of it; a rebuild can reconsider the whole arrangement. These options have different interfaces, unknowns and approvals.

For each option, request a concept, the area affected, the retained elements, a preliminary all-in cost structure and an occupancy plan. Keep the quality level and desired outcomes comparable. A cheaper option that does not solve the core problem is not an equivalent result.

Investigate the decision-changing conditions

Ask your team which structural, moisture, systems or other conditions might materially change the comparison. Review planning constraints, heritage considerations where relevant, site access and the effect on outdoor space.

Ask what investigation would reduce uncertainty and how much commitment it requires. The next good decision may be an assessment or measured drawing set, rather than selecting a construction route immediately.

Make the tradeoffs visible

Use a matrix for cost confidence, retained character, layout freedom, disruption, approval questions, comfort and future adaptability. Mark unknowns instead of scoring them as favourable.

Discuss the matrix with the design and construction team. The goal is a documented rationale for the next step and a list of remaining evidence. There is no universal percentage of house value or renovation cost that automatically makes rebuilding the better choice.