Building a sleep-out – a detached or semi-detached structure designed for extra accommodationhas become a popular solution in New Zealand for adding space without extensive renovation. However, like any structure intended for living or sleeping, it must comply with fire safety regulations to ensure the safety of its occupants. In New Zealand, fire safety for sleep-outs is guided by the New Zealand Building Code (NZBC), particularly the sections covering fire safety, means of escape, and materials. Understanding and addressing these fire safety considerations is critical to ensure compliance and protect lives and property.
This article provides a detailed overview of fire safety considerations for building a sleep-out, with references to the New Zealand Building Code and current best practices in fire engineering.
1. NZ Building Code Fire Safety Requirements for Sleep-Outs
The New Zealand Building Code outlines specific fire safety requirements that apply to residential buildings, including sleep-outs. Two key aspects of the NZBC that are particularly relevant are:
- C1-C6: Protection from Fire: These clauses cover fire safety requirements, including fire separation, means of escape, and control of internal and external fire spread.
- F7: Warning Systems: This section requires smoke alarms to be installed in sleeping spaces.
1.1 Fire Resistance and Separation
For detached sleep-outs, fire separation is a crucial consideration. The NZBC requires that any structure used for sleeping be adequately protected from fire spread, especially if located near other buildings or structures. Clause C3 of the NZBC outlines the fire resistance ratings (FRR) required for external walls based on the distance from the boundary:
- If the sleep-out is less than 1 metre from the boundary, the external wall must have a fire resistance rating (FRR) of at least 30 minutes. This ensures that the wall can contain a fire for 30 minutes, providing time for occupants to escape and for emergency services to arrive.
- If the sleep-out is more than 1 metre from the boundary, fire separation may not be necessary, but other fire safety measures still apply.
In addition to external fire spread, internal fire resistance is also important, especially if the sleep-out is attached to the main dwelling. In this case, walls shared between the sleep-out and the house must have a similar FRR to prevent fire from spreading between the two structures.
1.2 Smoke Alarms and Detection Systems
Smoke alarms are critical for early fire detection, particularly in sleeping areas where occupants may not notice a fire until it is too late. Under Clause F7 of the NZBC, all sleeping areas, including sleep-outs, must be equipped with smoke alarms that meet the following requirements:
- Photoelectric smoke alarms are preferred, as they are more effective at detecting slow-burning, smouldering fires, which are common in residential settings.
- Alarms must be installed in accordance with Section 7.32 of NZS 4514 (Interconnected Smoke Alarms for Houses), ensuring they are connected so that if one alarm sounds, all alarms in the house, including the sleep-out, will activate.
- Smoke alarms should be positioned in the hallway or area adjacent to the sleeping space to ensure early detection.
2. Materials and Fire Spread
The materials used in the construction of a sleep-out play a significant role in its fire safety. The NZBC provides guidance on the types of materials that can be used for both the structure and internal finishes to limit fire spread.
2.1 External Cladding and Roofing Materials
Exterior cladding and roofing materials should be non-combustible or have limited combustibility to prevent external fire spread, particularly if the sleep-out is close to the boundary or other structures. Common materials like brick, concrete, or steel cladding are often used due to their high fire resistance. Timber, a popular choice in New Zealand due to its aesthetic and thermal properties, can also be used but may require treatment or fire-rated barriers to meet the fire resistance requirements.
2.2 Internal Wall Linings
For the interior of the sleep-out, the choice of wall and ceiling linings is important to reduce the spread of fire internally. Plasterboard with a fire-rated core (e.g., 13mm fire-rated GIB board) is commonly used for internal linings, as it provides a level of fire resistance while also meeting other building code requirements for moisture resistance and durability.
Under Clause C3.4 of the NZBC, the use of combustible wall linings in certain high-risk areas, such as near cooking or heating appliances, should be avoided unless fire-resistant materials are used. This reduces the likelihood of ignition from accidental fires started by appliances.
3. Means of Escape
A fundamental component of fire safety in any habitable building is providing safe and accessible means of escape for occupants. This is particularly important for sleep-outs, as they are often smaller, self-contained structures that may have limited exit points.
3.1 Egress Windows
The NZBC requires that sleep-outs have at least one means of escape in the form of an exit door or egress window. For windows to be considered a suitable escape route, they must meet the following conditions:
- The window should have a clear opening of at least 850mm by 500mm to allow an adult to escape through it.
- The sill height of the window must not exceed 1 metre from the floor level to allow easy access.
Egress windows are particularly important if the main exit door is blocked by fire, providing occupants with an alternative escape route.
3.2 Escape Doors and Pathways
For a sleep-out that has a single exit door, the escape route must be direct and unobstructed. The exit door should open outward to allow for easy evacuation and should lead to a safe area, away from any potential fire hazards.
For larger sleep-outs or those with complex layouts, multiple escape routes may be required to ensure occupants can safely exit the building. The design of these routes must comply with Clause C4 of the NZBC, which ensures the pathway to safety is sufficiently protected from fire and smoke.
4. Heating and Electrical Safety
As sleep-outs are often smaller, compact spaces, heating appliances and electrical systems must be carefully planned to reduce the risk of fire. Common causes of fire in residential settings include faulty heaters and electrical malfunctions, so it is important to choose appliances that are safe and compliant with NZBC standards.
4.1 Safe Use of Heaters
When installing heaters in a sleep-out, ensure they are placed away from combustible materials such as curtains, bedding, or upholstered furniture. Electric heaters are typically safer than gas or solid-fuel appliances, as they do not produce open flames.
4.2 Electrical Wiring
All electrical work in the sleep-out should be carried out by a licensed electrician and must comply with AS/NZS 3000:2018 (Electrical Installations). This ensures that the electrical system is safe and capable of handling the load required to power appliances, lighting, and heating, without the risk of overheating or causing electrical fires.
Conclusion
Building a sleep-out can be an effective way to add space and flexibility to your property, but it is essential to prioritise fire safety from the outset. By adhering to the New Zealand Building Code requirements, including fire separation, smoke detection, means of escape, and the use of fire-resistant materials, you can ensure that your sleep-out meets the highest safety standards.
Engaging a qualified fire engineer or building consultant early in the design process can help you navigate these regulations and create a safe, compliant sleep-out that will provide peace of mind for years to come.
References:
1. New Zealand Building Code, C1-C6: Protection from Fire, 2021.
2. New Zealand Building Code, F7: Warning Systems, 2021.
3. NZS 4514: Interconnected Smoke Alarms for Houses, 2020.
4. AS/NZS 3000:2018, Electrical Installations.
At Veracious Fire Engineering Consultants, we are committed to promoting fire safety and compliance within the construction industry. Our team of expert fire engineers is well-versed in the latest New Zealand building code requirements and can assist you in navigating the complexities of fire safety regulations. Together, let’s create safer, compliant, and aesthetically pleasing spaces that enhance your lifestyle while prioritizing safety.
For more information or to schedule a consultation, please contact us at Veracious Fire Engineering Consultants. Let us help you build a safer future.
