Commercial-to-Residential Conversions near you

Room height is the first hurdle and the one most often assumed away. Part 10.3 requires not less than 2.4 metres in a habitable room other than a kitchen, and 2.1 metres in a kitchen, bathroom, laundry, sanitary compartment, corridor, passageway or garage, with 2.0 metres over the nosing line of a stair. A warehouse usually passes this easily and an office floor with a suspended ceiling and a raised floor often does not, particularly once new services are threaded through.

Condensation management is the second, and it is the provision most frequently missed in a conversion. Part 10.8 requires a pliable building membrane in an external wall to comply with AS 4200.1 and to sit on the exterior side of the primary insulation, and sets minimum vapour permeance for material outside that insulation of 0.143 micrograms per newton second in climate zones 4 and 5 and 1.14 micrograms per newton second in climate zones 6 to 8. A commercial envelope insulated on the inside without regard to those rules will produce condensation inside the build-up.

Fire and smoke provisions are the third. Where the Housing Provisions apply, Part 9.3 governs separating walls and floors and Part 9.5 governs smoke alarms, and Volume Two clauses H3D4, H3D5 and H3D6 tie those back to the performance requirements. Part 9.4 deals with fire protection of garage top dwellings, which is directly relevant where parking sits under the new residences.

Commercial floorplates are deep. That is efficient for offices and warehouses, and unhelpful for dwellings, where habitable rooms need natural light and ventilation and the Code's ventilation provisions require openable area related to floor area. Getting daylight into the middle of a deep plan usually means courtyards, light wells or roof glazing, all of which cost floor area and money, and all of which are cheaper to design in than to retrofit after approval.

Acoustics are the other inherited problem. A converted building often sits in a mixed-use setting with traffic, loading docks, plant, licensed premises or an ongoing commercial tenancy below. Noise between the new dwellings matters too, because the slabs and walls in a commercial building were never detailed for the impact noise that separates neighbours from each other at two in the morning.

Then there is what remains in the building. Asbestos is likely in Australian commercial buildings of a certain age, and its forms are more varied than in housing. Contamination is a live risk on former industrial and automotive sites. Both are cheaper to find during due diligence than during construction, and both can end a project, which is exactly why they belong before the design fee rather than after it.

A conversion needs a planning decision that residential use is acceptable on that site, and a building approval that the converted building complies with the requirements for its new classification. They are separate processes with separate decision makers, and satisfying one says nothing about the other. Planning is concerned with land use, amenity, parking, overlooking and the character of the area. Building approval is concerned with the Code.

Because the approval systems, the role of the building surveyor or certifier and the inspection regimes differ across the states and territories, the only reliable step is to establish your own state's pathway at the outset. Where the result is an apartment building rather than individual houses, additional state regimes may apply to the design and certification of the work, and those are also state-specific. Ask a building surveyor in your state what the conversion will be classified as and what that classification requires, before an architect starts drawing.

A conversion produces a building with two histories, and the second owner will only ever see the second one unless you write the first one down. Keep the original building's documentation where it exists, the hazardous materials survey and any clearance certificates, the contamination assessment, the structural documentation for anything that was altered, and the certificates for all services work.

That file does real work later. It tells a future purchaser's inspector what is behind the linings, it tells an insurer what the building is made of, and it tells the next engineer what was done to the structure and why. On a conversion, where almost everything interesting is concealed, the documents are the only durable record that the work was done properly, and state licensing and residential building insurance requirements for the builder sit on top of them.