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How to Turn a Storage Unit into a Granny Annexe

  • Conversion
12th February 2019

Storage units have massively grown in popularity within the realm architecture in recent years. This increase in popularity is due to the inherent strength, wide availability, and relatively low expense of them. They are also a more eco-friendly building option.

All these beneficial features, along with their inherent shape and material, mean they can be easily modified to fit many purposes, especially the purpose of building granny flats. Unlike traditional dwellings, very little construction is required when creating a granny annexe from an existing module. This article will outline how to turn one of these into a granny annexe.


Doing research is the first and most important step to converting to a granny annexe. Find out all the local regulations, restrictions, and requirements before you begin the process. Each local area will have its own zoning rules to follow so be sure to be in contact with your local council.

There are many different types and sizes available for hire and sale with SJones so it is important to also do your research on what is the best option for you and to find what exactly you are looking for. Also, research whether it is possible to get onto your land. Local companies will often be able to give you a free quote to check access to your site.


There are endless options when it comes to designing prefabricated units. However, with every modification, you risk making these weaker so think through your design carefully. So although modules are structurally strong and flexible in their design possibilities, they aren’t designed to be cut and rejoined multiple times so it is important to only cut them when you need to.

There are some key features that have to be included in the design process to be able to make it a habitual area. This includes: doors, windows, internal walls, ventilation, lighting, flooring, hot-water system, plumbing, draining and sewerage, electrical connections, and insulation. Insulation is a key element to create a homely feel for your granny annexe and adds a layer of privacy and acoustic barrier.

Insulation helps lengthen the life of the product as well as the water vapour in the air will not condense, avoiding mould and corrosion on its’ surface. Proper insulation will also reduce your energy bills by keeping the heat inside during winter and keeping the annexe cool in summer.


Many people are turning to granny flats as a cost-effective alternative to traditional building. There are many additional costs involved though. These extra costs include: certificates and reports, modifications, architect fees, a foundation, transportation, plumber and electrician and other labour fees, waste removal, and landscaping.


A unit requires preparation for transportation so it is important to plan its journey to your property carefully. This includes plotting the route it will take and ensuring those streets are safe for an oversized vehicle. Remember to consider low-hanging trees, low powerlines, bridges, or any busy or hazardous roads (traffic control may need to be organised).

Once your route is approved by Council, you can then present it to your transport company. Make sure your land is ready for the company when they deliver. Make sure your foundation and connections are complete so it can be installed as soon as it arrives.

Make it a Home

Once the granny flat is in place on a secure base, you will be able to add your personal touches to it. With a nice coat of paint and the right design elements, you can add a homey and chic feel to your granny annexe. A prefabricated home is a great blank canvas to add design elements to. So have furnishing, painting, and decorating the space and truly make it your own. The possibilities are endless!

Using a unit to create a homey and safe granny annexe is highly achievable. It may appear to be a daunting task but when broken down it becomes a simple and doable project – and definitely a worthwhile one! So we hope this article will help you to create the perfect granny annexe for your needs.

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