How much does a loft conversion or second storey addition cost in New Zealand?

ARTICLE Stephanie Matheson

An average loft room conversion / second storey addition in New Zealand will cost approximately $200,000* to $450,000+*. These days many people are deciding to stay in their homes and maximise the space they've got. Here is how you can make the most of your loft while keeping renovation costs down. 

Where do I start?

Loft conversions typically require structural and foundation work, as the original house was not built to hold the weight of a second storey. In many cases, extra steel and or timber beams have to be installed to support the new first floor. Keeping the number of steel beams down – and using timber for strengthening where possible – will help you keep your building costs down. In addition to the new steel or timber sub-structure, often the existing flooring needs to be underpinned and strengthened. This kind of foundation work is usually the biggest unknown factor in terms of renovation costs – until it’s been properly designed and engineered by your architect.

Weather-proofing during the build is one of the main concerns when the roof has to be removed. Full scaffolding that can be wrapped in plastic shrink wrap is a good option that provides water-tightness and allows the builders to work in any weather thus helping to avoid weather-related delays that can be costly both in terms of time and money.
With all this extra building work required, it’s not surprising that loft conversions are typically more expensive than same level extensions. They do however allow you to maximise space while maintaining the home’s footprint, which is often key in denser, urban areas. You should allow at least between $200,000 and $450,000 for a medium to large addition. This would include materials (including scaffolding and shrink wrap), labour and project management and is a rough estimate for the complete project from start to finish (ready for you to move in).
Cost of a loft/second storey addition
From $200,000 - $450,000+*

Is my roof suitable for a conversion?

Generally speaking, the steeper the pitch of your roof the more likely it is that your roof will be suitable for a conversion. Not having to alter the roof itself will keep your costs down, as you will only need to install skylights or dormer windows into the pitch of the roof to provide natural light. If you are changing your roofline or an existing roofing product you will need to apply for Building Consent. Depending on your situation, for example if you are infringing on any height-to-boundary requirements, you may also need Resource Consent.

What type of window styles can I choose from?

Skylight windows are the most cost-effective window style to install. They let in plenty of light; however, as they are flush with the roofline they will not help create any more headroom. Dormer windows create this precious extra headroom that protrudes from the sloping roof, so they are a great option when you want to maximise the available attic space. If your budget allows, you can even consider installing French doors or sliding doors with a glass balustrade or small balcony. These solutions create the feeling of a more open space and let natural light flood in.

How do I maximise my loft space?

Making provisions for well-designed, built-in storage will help you maximise the space you’ve got and keep your loft conversion looking neat and tidy. Custom-made cabinetry and storage solutions are the most efficient options if your budget allows this. You’ll be able to use every nook and cranny and create a seamless look that helps to streamline your loft layout. In addition, choosing the same colour or colour tone throughout your whole extension will help create the illusion of more space.

What are my stairway options?

Carpet wrapped steps are your most cost-effective option when it comes to stairways. A set of straight stairs are easiest to build and install, and hence very affordable. Depending on your space and requirements, however, a set of turning stairs might be required. If you choose different materials such as hardwood timber or glass for the steps or the balustrade, this will increase the cost. Floating steps or curved staircases – in the upper regions when it comes to price – add a bit of drama and visual impact. Floor level lighting and art embedded into the steps add further to the wow factor. Hometec's Attic Stairs are a simple alternative and are a great option for those who are working within a small space.

Stairs are generally easy to build and install, however, careful planning and positioning at the outset of your project is important to ensure you don’t lose precious space on your ground floor. As a rule of thumb, it’s likely that stairs will take up about half a small room. Where space is extremely tight you could consider a small spiral staircase, keeping in mind though that access can be an issue and items of furniture may have to be lifted in and out through the upstairs windows.

What is involved in a roof conversion?

Not changing your roofline means that you are likely able to leave most of your roofing untouched. You will simply need to tidy up and repair roofing where your windows will be inserted. However, any work done on a roof requires a scaffold or edge protection, which will add to the cost of your project (and is factored into the rough estimate). Also, it’s not uncommon for problems such as old leaks and rot of roof beams to be uncovered during the build. Ensure you have a contingency budget of at least 15% planned in.
If your roof conversion is a more substantial project you may have to replace some or all of the roofing. Costs for replacing or repairing a roof depend on the roofing material of your house and other factors. Metal roofing is the most common roof type in New Zealand and it is also the most cost-effective option. Plan in around $200+* per m2 to replace an average-sized corrugated iron roof. Other roof types will be more expensive.
Asphalt shingles are becoming more popular, as they are generally low maintenance and very tough, with some heavyweight shingles offering 50-year warranties. Concrete tiles are also hardwearing and have the advantage of reducing heat loss and noise levels from the outside.

Looking for inspiration? Make sure you check out our completed loft conversion projects.

 
This home renovation advice article featured on page 84 of Issue 016 of New Zealand Renovate Magazine. New Zealand's first and only magazine solely dedicated to home renovations.

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*Costs are rough estimates and are subject to change - GST is not included unless otherwise stated. For a fixed-quote accurate to your specific project, please consult your local Refresh Renovations specialist. All Refresh Renovations franchises are independently owned and operated.