Introduction: How to Design the Ultimate Off-Grid Tiny House!

About: I am a high school student from South Australia with a passion for making things, especially electronics. Over the past year I have been working on Project Summit, an extremely overkill model rocket with activ…

The tiny house movement has grown exponentially over the past decade and is quickly sweeping across the US, Canada, New Zealand, Australia and many other countries across the world. The definition of what defines a ‘tiny house’ varies, though a typical tiny house floorplan is generally considered to be 9-37 square meters (100-400 square feet), compared to the average 241 square meter (2600 square foot) typical US home.

Tiny house financial costs fluctuate a lot depending on the building materials that are used, who builds it and what size it is, however the average tiny house costs $30,000AUD. For comparison, a standard home costs an average of $650,000AUD when including both the house cost and interest on a 30-year mortgage, and that’s not including maintenance, insurance or tax! On average, one third of the income of a US adults income goes towards their house over a 30-year mortgage, whereas a tiny house can easily be entirely paid off within two years.

These important financial factors are the main reason for the recent growth in the tiny house movement, though there are many other important factors that make it appealing to people. Tiny houses have a low environmental impact (especially when off-grid, not connected to mains water or power), allow more time to travel and live, involve easier maintenance, allow customisation and downsizing and life simplification. You will use less energy as you are heating/cooling a smaller space. If it doesn’t fit in the house, you won’t buy it so you will spend less money. You don’t need a septic system if you use a composting toilet or connect to a sewer. Finally, you can still fit everything you need in the house if it is designed well.

On the flipside there are of course negatives to this unique lifestyle. You will need to clean more frequently as you are living in such a small space. The legalities are questionable in some areas in terms of building codes and minimum house sizes. There is little storage space. When living with others you will always be in each other’s space.

Tiny houses are not just a ‘trend’, but a change of lifestyle. The small size of a tiny house is certainly not for everyone, but here is a guide on how to go about designing one for those who are interested, like me!

Step 1: Getting Started

The first thing to consider when designing your own tiny house is what you want. What does YOUR house need to include? Get creative, no idea is impossible until it has been proven to be. Consider foldaway furniture to save space, use plenty of wall space for storage, consider light colours and lots of windows to make the space feel larger, use every little space for storage, maybe a deck for more living space? Write down every idea that you get and start considering a floorplan. Explore existing homes and draw some rough sketches of what your house could look like.

Consider using various types of technology such as automation and ceiling speakers, go off-grid with a wood fire place and solar power, build your hobbies into the house design, add space for pets and find the perfect colours for how you want to live. One of the best benefits when designing a tiny house is that they use far less materials, allowing you to spend more on quality materials throughout your build. When designing my tiny house, I try to be as creative as I can. I love electronics, saving money, and technology, so I will be including a large office space, off-grid capability and I’ll be making it portable to avoid paying council rates and other hidden fees. When a tiny house is on wheels it is under caravan and RV laws, giving a legal loophole and avoiding building codes and minimum dwelling sizes.

Step 2: Floorplan and Interior

Now that you have some sort of brief sketch and a bunch of ideas of what your house may include, it is time to plan each ‘zone’ and make an official floorplan of the house. I did this by making a list of what each zone needs, such as the office, kitchen, bedroom, living space and deck. Once you are sure what each zone needs, make a final floorplan of the house. The best thing to do at this point is to map out the entire living space on the floor with masking tape. This allows you to get a feel for the dimensions, how you will move about the space and make some adjustments before the design is set in stone.

Step 3: Exterior

The exterior is the first thing that people will see, so it is time to decide what style home you want and if you want that ‘wow-factor’ when people first see it. At this stage in planning, it is likely that you have already decided on an exterior style, so it’s time to figure out exactly what colours and materials will be used and what shape the building will be. Make some sketches and create a 3D model to visualise your home, using Sketchup will let you to find dimensions for different sections. I’ve targeted an industrial-style and used lots of dark Colourbond steel and wood to create a unique look. I’ve also decided to include a large deck. This maximises my living space and allows me to entertain with the use of a BBQ, pizza oven, fire pit and lots of outdoor lighting.

Step 4: Trailer

Most of a tiny house build can be done DIY with some research, however the trailer is the one thing that I will be paying a professional to build for me. The trailer is the main structural part and has a lot of engineering involved to get right, otherwise there is potential to lose your expensive house during transport. The trailers deck will be 2.3m wide, 8m long and will include wheel wells to bring the deck closer to the ground, allowing a much more spacious living space. It is also recommended that the trailer includes foldaway jack stands on all corners for easy levelling and support when the house is parked, so the house is level and the plumbing works correctly.

Now it’s time to decide if your trailer will be the base of your home or if you will build a subfloor on top of it. Using the trailer as the subfloor means the crossmembers need to have 600mm centres, routing electrical cables and pipes will be tricky and the underside will need to be sealed so the trailer can hold insulation. The benefit of this is that it allows a higher ceiling, is often cheaper and looks nicer from the outside. My biggest problem with this is the lack of insulation where the greywater tank will be and where the large steel members are. These will be ‘weak spots’ in the insulation and make the house less energy efficient in terms of heating and cooling.

Step 5: Wall and Roof Framing

Consider hiring a professional contractor to design this important structural part. If you use a contractor, it is important to make sure they understand they are working with you and are aware that it’s a tiny house, not a standard house, the structure will therefore be slightly different.

Wall frames have an array of important components that allow the structure to be safe. The top plate runs across the top of the wall frame and supports the ceiling structure. The bottom plate is the same, but on the bottom instead. Studs are the vertical members between the top and bottom plates that take most of the load. Jack studs are similar, but are shorter and go between the plates and window framing. Jamb studs go either side of an opening for additional support to ensure the noggings above the opening cannot slip from loads. Noggings go horizontally between studs, when combined with bracing (plywood sheets or steel strapping) they ensure the wall cannot twist or warp. Bracing is very important on a transportable tiny house due to the stresses during transport.

The most important thing to consider when designing framing is that everything must be millimetre perfect. It is a process of detail and accuracy. Design each frame according to the features on the wall and the load that it will take. It’s ideal if all studs are a maximum of 450mm apart for optimum strength during transport.

Step 6: Electrical

Electrical systems are extremely broad as every system will have varying features and purposes. My system is designed to be off-grid by using solar power, so this section will only focus on off-grid systems. The solar system will charge batteries which will power 12V lighting and USB charging ports. An inverter will then be used to convert the 12VDC into 240VAC to power appliances such as my computer, refrigerator and other electronics.

An electrical system must include a distribution board, which distributes the electricity through different circuits in different zones such as ‘kitchen receptacles’ or ‘office lighting’. A circuit breaker should be included for the whole house, many smaller circuit breakers should be included for each section to provide safety.

The equation I = W/V can be used to find the maximum load on a circuit, such as a toaster 1050W/120V = 8.75A. As voltage is proportional to power, using 12v lighting saves a lot of power. It is important to use this equation to find how much load will be on the house at any time to understand how to power the house.

To calculate the size of your solar system, list everything your solar will power and how many watts is uses per hour. List everything from the refrigerator, to your computer and how many devices will be charging at once. Multiply this by how many hours the appliance will be used each day to figure out how many watts the system must generate. Work out how long the sun is shining each day to find how many watts each panel will produce. Figure out how many watts you will use each hour, add 40% to this and that shows how many panels you need in watts.

Step 7: Plumbing

When plumbing a tiny house it’s recommended that you keep the design basic and use basic materials to make it faster, easier and leave less room for catastrophic error. My plumbing setup is designed for on and off-grid use, so there will be an efficient tankless gas hot water heater and an inlet for a water hose on the side of the house. The basis of my system will include an inlet (from the gutters), a 1-way valve between the inlet and the tank, a medium-sized tank, an automatic pump to keep pressure, a hot water heater and of course the taps and other outlets throughout the house.

To make plumbing the easiest in a DIY build and save weight on the house, use PEX piping and brass elbows. Another recommendation when going off-grid is to use a low-flow shower head to conserve water. A greywater tank for all the used water will be underneath the trailer and will be dumped when it’s raining or filtered and used for watering gardens.

When plumbing, take your time to ensure every fitting is perfectly sealed, as any error in this system may cause major damage to the house. As I am targeting an industrial style, all my plumbing will be exposed on the walls of the house and thus easily accessible if a problem occurs.

When designing a gas system, it’s important to include two gas tanks with automatic switchover, easy access to the pipes in the event of a leak and a gas detector to alert you.

Step 8: Conclusion

Designing a tiny house is no easy task. It is time consuming and will involve a huge amount of research. But by using the recommendations in this tutorial, you will be well on your way to designing your dream tiny house.


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5. Tiny House Electrical Diagram 2020, Graphic Illustration, Yugteatr, viewed 3 November 2020, .

6. Tiny House Plumbing 2020, Graphic Illustration, RV Insight, viewed 3 November 2020, .