The information in this guide is general in nature and we strongly recommend that you seek the professional BAL Assessment of your property.
We are often asked the question – what about designing for bushfires? We all share the goal of safeguarding our tiny homes, especially when living in beautiful bushland areas where bushfires are a potential threat.
So, what strategies can be employed to construct our tiny homes to effectively withstand the most challenging aspects of nature?
Tiny homes may seem highly mobile, giving the impression that they can be easily hitched and relocated out of harm’s way, especially in the face of an impending fire. However, it is crucial to dispel this misconception, as attempting to hastily relocate a tiny home during such emergencies is not only ill-advised but also laden with inherent risks.
Firstly, moving a tiny home is not as swift and straightforward as it may appear. Unlike simply backing up a truck, tiny homes are equipped with infrastructure, often accompanied by decking and landscaping around them. Consequently, the relocation of a tiny home can be a time-consuming endeavour, taking several hours or even an entire day.
Secondly, not all vehicles are capable of towing all types of tiny homes. Our smallest models, weighing 3.5 tons, can only be towed by the largest consumer vehicles. Larger 4.5-ton models necessitate commercial or industrial trucks, which are not readily accessible for most individuals in the event of a sudden emergency.
Lastly, wildfires are notoriously unpredictable and can advance rapidly. Attempting to tow your beloved tiny home away from the path of danger may inadvertently result in the very accidents you are seeking to evade.
In light of these considerations, it is of utmost importance never to endeavour to move your tiny home urgently when confronted with a fire threat. Instead, focus on preventative measures to safeguard yourself and your home.
We turn, as we often do in tiny home design, to the traditional construction industry. Australian fire services have developed the Bushfire Attack Level (BAL) framework to describe bushfire risk, and construction experts have related this framework to construction details and prescriptions. When a new building is constructed, these BAL ratings determine what needs to be done for the building to be safe for occupancy. We can apply these same guidelines to tiny homes! Below is a highlight of the main measures that can be taken to meet the different BAL levels.
Tiny homes are not permitted and designed as traditional structures when it comes to bushfire levels, as they are classed as caravans and can be placed in any location for indeterminate lengths of time. So, any construction to a BAL rating is done voluntarily. We strongly recommend that you understand your areas’ BAL rating, and you might even employ the expertise of your local council for a BAL Assessment.
BAL-LOW is the lowest rating. It indicates the lowest risk of potential fire, where there is insufficient risk to warrant specific construction requirements. With a BAL-LOW rating, you must ensure proper maintenance of the property, such as clearing vegetation and debris.
At this level, risk is primarily from potential embers during a fire. The building is designed to protect against radiant heat up to 12.5kW/m2. At this BAL rating, all external cladding must be non-combustible, meaning there are limits to the timber cladding that can be applied. No softwoods or recycled fence palings, but some denser hardwoods are allowed. All vents must be screened with a metal mesh. On site, the subfloor must be enclosed with a non-combustible material, bushfire resistant timber, or a perforated steel mesh.
Source: My Builder Certifier BAL 12.5
BAL-19 and BAL-29 are functionally similar when it comes to building design. This category has high risk, particularly from embers, debris and heat. The building is designed to withstand radiant heat up to 29kW/m2. At this level, in addition to the requirements of BAL 12.5, only very dense hardwoods can be used as external cladding. Ember resistant gutter guards must be installed, and 5mm toughened glass must be used on the outside pane of all double glazed windows!
Source: My Builder Certifier BAL 29
At this level, the building is at a very high risk of impact from embers, debris, heat and potentially flames. The building is designed to withstand radiant heat up to 40kW/m2. In addition to the requirements of BAL-29 and below, BAL-40 requires 6mm toughened glass on the outside pane of all double glazed windows, and excludes timber from the external cladding entirely.
Source: My Builder Certifier BAL 40
BAL-FZ is the most extreme category of bushfire rating, characterised by direct exposure to a roaring fire front. BAL-FZ is extremely difficult to achieve in tiny home design. Some intrepid designers have carved out a niche by building specifically to exceed this standard, optimising for performance in bushfire ratings above all else! The biggest challenge with building to BAL-FZ is the need for metal shutters blocking the windows entirely in the event of a fire. Traditional fire shutters can’t be fitted to tiny homes due to their size impacting the overall width of the tiny home, preventing their classification as a caravan.
As you can see, meeting some of the requirements for bushfire as laid out in traditional construction, is available in tiny home design! You should deeply and holistically consider your tiny home bushfire plan before purchasing your tiny – upgrades like toughened glass and metal cladding are easy to change upfront, not so once it’s built! With the right preparation, your tiny home can be built suitably to whichever landscape you like to enjoy.
We must stress: the information in this guide is general in nature and we strongly recommend that you seek the professional BAL Assessment of your property.