How to plan a renovation when you do not know what is behind the walls

Start with the decision that could change

I would take your main renovation idea and finish this sentence: we would need to rethink this if we discovered that… You do not need to diagnose the building. You are identifying where a missing answer could influence the layout, scope or spending.

For a hypothetical kitchen renovation, you might want a wide opening between two rooms. Before treating that opening as settled, ask the design team what needs checking about the existing building and who should assess it. Keep the wish separate from the assumption that it will be straightforward.

• Which feature does the whole idea depend on?
• What information supports it so far?
• What finding would make us consider a different option?

Give each investigation a clear purpose

I would ask for a short explanation before commissioning an investigation: what question are we answering, how will we investigate it and which decision will the result inform? A useful answer might come from reviewing records, a site assessment or further specialist input. Let the appropriate professionals advise on the method and any permissions needed.

If opening part of the building is proposed, ask who will organise the work, how it will be made safe and who is responsible for making good afterwards. This is something to plan with your team, not an invitation to start removing finishes yourself.

• Ask what the investigation includes and excludes.
• Confirm the proposed cost and who will arrange it.
• Find out what could still be unknown when it is finished.

Put the questions in order

Some answers matter before you choose a layout. Others can wait until the design is more developed. I would prioritise the question whose answer could overturn the most work, rather than collecting information without a clear reason.

Make a simple list with four headings: question, person to ask, decision affected and needed by. For each unresolved item, agree whether to investigate now, carry an explicit assumption or keep another design option available.

• Mark decisions that are waiting for information.
• Avoid describing an assumption as a confirmed fact.
• Revisit the list when the design changes.

Agree what happens when something turns up

I would establish a simple communication routine before building starts. Who tells you about a discovery? Who explains the options? Who checks the effect on cost and timing? Agree the route for a decision so you are not trying to invent it during a busy working day.

MBIE advises keeping written records of decisions and contract changes, including checking their price and timing implications. If a proposed solution changes consented building work, council approval is a separate consideration. MBIE says the building consent authority needs to approve the variation before that changed work is carried out.

• Ask for a clear description of the finding and proposed response.
• Confirm the relevant design, pricing and approval steps.
• Keep the agreed decision with the project records.

Leave room to talk through alternatives

An unexpected answer does not automatically tell you which option suits your household. I would want time to explain the choices in plain language and hear what matters most to you before settling the next step.

In her published feedback about a Waiheke holiday home reconfiguration and extension, Alison describes receiving explanations and design options as her ideas developed. That is the sort of communication worth asking about when choosing your team.

Bring your biggest unanswered question

If you are considering a renovation, bring the change you want to make, any existing plans and the thing you are least sure about. We can discuss what would be useful to establish next through an initial conversation with Modal Architecture.