Sleepout & Cabin Cost Calculator NZ 2026

This calculator estimates the all-in cost of building a sleepout or cabin in New Zealand, an increasingly popular way to add a bedroom, home office, teenager retreat, guest room or rental space without the cost and disruption of extending the main house. The price depends first on the type and finish. A basic uninsulated cabin used as a sleepout is the cheapest, an insulated and lined sleepout suitable for year-round use costs more per square metre, and a unit with its own bathroom and kitchenette, effectively a minor dwelling, is the most expensive because of the plumbing and fit-out. On top of the building itself, the costs that catch people out are the site works and foundations, connecting power, water and wastewater, and, importantly, building consent and council requirements. In New Zealand, a small detached building under 30 square metres can be exempt from building consent if it meets specific conditions, but anything with plumbing or sleeping in certain configurations usually needs consent, so it pays to check with your council early. You enter the floor area, choose the type, and add figures for site works and foundations, services connection and consent, plus a contingency. The calculator returns the all-in estimate, the building and site components, and the cost per square metre. Use it to compare a cabin against extending the house, to test whether a sleepout stacks up as a rental, or to budget before talking to builders. Costs vary widely by product, site, slope and access, and consent rules differ by council, so treat this as a planning estimate and confirm requirements locally.

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$69,575
estimated all-in cost
Building$50,000
Site, services & consent$10,500
Contingency$9,075
Per m²$3,479

Buildings under 30m² may be consent-exempt if they meet the rules; plumbing usually needs consent. Check your council. An estimate; get quotes.

How it works

The building cost is the floor area times the per-square-metre rate for the chosen type. Site works and foundations, services connection and consent are added as separate figures, then a contingency is applied to the whole lot. The per square metre figure divides the total by the area.

Worked example

A 20 square metre insulated sleepout at $2,500 a square metre is a $50,000 building. Adding $5,000 for site works, $3,000 to connect power and water, and $2,500 for consent gives $60,500, and a 15 percent contingency of about $9,075 brings the total to roughly $69,575, around $3,479 a square metre all in.

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Frequently asked questions

How much does a sleepout cost in NZ?

A basic cabin can start around $1,500 a square metre, an insulated sleepout around $2,500, and a unit with a bathroom and kitchen around $3,500 or more, before site works, services and consent. A typical insulated sleepout all-in often lands between $50,000 and $80,000.

Do I need consent for a sleepout?

A detached building under 30 square metres may be exempt from building consent if it meets specific conditions, but adding plumbing or using it for sleeping in certain ways usually requires consent. Rules vary by council, so check before you build.

Is a sleepout cheaper than extending the house?

Often yes, because a detached cabin avoids tying into the existing structure and can use simpler foundations, though connecting services and meeting consent rules add cost. Compare the all-in figure here against an extension quote for your situation.