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In my experience working with tiny houses, I’ve talked a lot about how to construct and transport them in a manner that will ensure safety for their occupants and use on the road. Teaching in the area of building and construction, I have designed my own tiny house prototype and am passionate about helping people understand the complexity of building a moveable tiny house.
I often get asked about if tiny houses need to comply with standard building codes. The reality is, that in terms of transport, a tiny house on a trailer is categorised as a caravan, so it’s just the trailer that needs to meet vehicle regulations and be registered to travel on the road.
You can build any manner of structures on top of your trailer, from dog kennels to tiny houses. However there are limits to transporting a tiny house on the road without a permit, and they include a height of no greater than 4.3m, a maximum width of 2.5m, and a length of 12.5m. The trailer has to be constructed to an approved rating for the total weight limit. Let’s face it, tiny houses are different to caravans – they are generally larger in height, longer and most certainly heavier.
Points to consider before you transport your home:
- Tiny houses are generally not aero-dynamically designed and are often prone to movement from gusts of wind, due to their large surface area.
- They will usually have a higher centre of gravity than a caravan and have the potential of rolling over.
- They can sway when being towed and can become a danger to other road users. Caravans sometimes have anti-sway bars but I have not seen these yet on tiny houses.
- How you go about securing your load is most important. You will need to secure the tiny house to the trailer from the roof to the floor with a strong connection system, as you will be exposing your tiny house to extreme wind loads during movement. Unfortunately there have been disaster stories of tiny houses falling apart on the road during transport. And of course, we want to avoid this at all costs.
The National Construction Code
As you can see, it’s important that you understand the potential implications of your building decisions. I have assessed tiny houses and their relationship with Volume 2 of the National Construction Code for housing in Australia and have discovered that they can be built to comply with most areas of it, whilst a couple of areas they cannot comply with as easily. I will cover these off as I go, but I first want you to know that you can download the NCC from the Australian Building Codes Board website abcb.gov.au, and register to download NCC Vol 2 for free.
Complying with the codes
To start with, let’s talk about the substructure, which in the case of a tiny house will likely be a steel trailer. As mentioned in our last blog post regarding material selection, the trailer should be engineer-designed to support its own weight, the weight of the tiny house, and the weight of its furniture post construction. From the substructure, you work upwards – to the subfloor, the structural walls, windows and doors, roofing system, flooring, insulation, internal walls and lofts. Regarding cabinetry and furniture, Youtube is a great resource for diving deeper, with all kinds of tips on tiny house internal fit-outs.
The subfloor is where you connect to the trailer. Usually there will be beams to connect to, which act as bearers. The timber or steel members that you will connect to the bearers are joists, and they need to be appropriately sized and spaced to minimise any spring in the laying of flooring. The combination of the trailer beams and joists will support the weight of the walls, windows and roof.
The structural wall will be made up of either a steel or timber frame, or something like what I use, which is a structurally insulated panel for speed and ease of construct. If you are building a wall frame, you will need to follow the requirements set out in the Australian Standard 1684 for timber framing including the lintels over the openings of the doors and windows.
Once the wall frame is erected, you can then start working on the roof system you have designed. You will need to ensure that your roof system is properly secured to the wall frame to avoid separation in the case of an uplift. You will then need to brace the roof and wall frame with steel or timber bracing to prevent a process called racking, which is the movement of the systems resulting in collapse.
Sarking and sisalation
Before installing the roofing material, you should next look to install what’s called ‘sarking’ or ‘sisalation’, which is a reflective builders wrap that attaches around the wall frame and roof system. You will need to follow the installation requirements found in the NCC to ensure sarking is installed properly and prevents moisture entry. Once it is in place, the roof battens then need to be installed. The roofing material will need to be thoroughly secured to the roof structure to avoid it being dislodged during transportation.
Window and door installation
Next, you’ll want to Install the windows, door and wall cladding as per the manufacturer’s instructions to make sure your house is water tight. Once it is, move inside and start installing the wall insulation between the studs and the roof insulation between the rafters, without compressing the insulation. For the windows, I often use thermally broken double glazed glass as these will help to keep your home warmer in winter.
You should then lay down your flooring material and screw it into the joists to reduce spring.
Generally you will be constructing some other internal walls – perhaps for a bathroom, for a bedroom divider, or to support your plumbing pipes. You may also want to construct a loft to ensure that you have secured it properly to the structural walls. You can then select appropriate materials according to strength for the anticipated loft load.
Lining your walls
Once the walls are constructed you can then line them. There are a number of materials you can use. You can line them with plasterboard, marine ply for its natural texture, or perhaps reclaimed timber. The choice is yours, but remember to consider the weight of each material.
Lastly, if you have a loft, you will need either a ladder or stairs to access it. If you use a ladder, ensure that it is not positioned directly vertically and that the rungs are deep, otherwise it will be a difficult climb. As for the stairs, they should be built to allow ease of access and meet the step requirements outlined in the code. However, this is difficult to achieve in most tiny houses, due to space limitations.
What tradies will I need to assist with my construction?
It is important that you use a licensed electrician for all your electrical work, and a licensed plumber, roof plumber and gas fitter for water, wastewater, and gas connections. You must also get professional assurance that your roof is watertight.
Today we have covered a lot of considerations to take onboard when building your tiny house. The key things are to build a structurally sound and sturdy house that will withstand transport, and to create a home that is comfortable and safe for its occupants.
If all of the above sounds like too much to handle, don’t be deterred. Building a tiny home is very do-able. Afterall, I did it myself! To make the process easier for my clients, I have created my tailor made Tiny Home Kits which provide you all the building materials you need and a construction manual to get you started. Please do not hesitate to get in touch to discuss your options.
Next time we’ll chat about what to consider when going off the grid.
Until next time,
The Tiny House Guru