6-Types of Sustainable Building Materials for ADU Construction

ADUs are a popular trend in modern housing. These buildings are secondary housing units on a single residential lot; they are also known as backyard cottages, granny flats, or in-law apartments. They can be constructed independently or as an addition to an existing house.

They provide an adaptable way to increase living space and host in-laws.

When designing an ADU, using sustainable materials is a great way to reduce your influence on the environment. Nevertheless, abundant materials can make it challenging to determine where to start.

Therefore, we will explore the best sustainable building materials for your ADUs.

What Are Different Types of ADU Construction Materials?

Selecting suitable materials for an Accessory Dwelling Unit (ADU) is critical for ADU contractors. Every material has a distinct set of benefits and drawbacks. Let’s examine some of the most popular materials utilized in building ADUs.

Concrete and Brick

Concrete and brick are solid and durable materials ideal for ADUs due to their resistance to termites, rot, and fire.

However, their framing requires a strong foundation, increasing construction complexity and cost. It also requires specific skills and tools, making it more labour-intensive than wood or steel framing.


Wood is a budget-friendly and versatile construction material; it is ideal for ADU construction due to its ease of handling and versatility.

However, it is susceptible to termite damage and rot and poses a higher fire risk than non-combustible materials.


Steel framing offers durability and resistance to termites and rot. Its non-combustibility property makes it a safe choice for long-lasting structures.

However, it can be more expensive due to the specialized skills and tools required. Similarly, the construction process with steel is more complex and costly than others.

Additionally, some steel components, such as adjustable steel stumps, are durable, cost-effective, flexible and withstand harsh weather conditions. They offer greater flexibility in height adjustment, are lighter, and are easier to install than concrete stumps.

Moreover, they give structural integrity and longevity to ADUs.

Rammed Earth

Rather than being a material itself, rammed earth refers to a building process. To construct anything with this method, you must condense a few resources, such as gravel, chalk, and lime.

A sustainable option, it requires less energy to construct, uses natural materials, and has minimal impact on the environment. It also has excellent insulating qualities and is incredibly durable.

Straw Bales

An environmentally friendly alternative for shed roofing is straw bale construction. However,It is not impossible to use them as the main structural component of a building. They are ideal as filler materials between columns because of their capacity to block out sound.

They provide superior fire resistance and insulating qualities, which are good because they can lower your building’s heating and cooling expenses.

Although it is widely considered a waste product, straw is a plentiful and renewable resource. Bales of straw are a resource that builders may reuse and reduce waste by employing in their construction.

Sheep’s Wool

Wool may break down organically without releasing dangerous chemicals into the environment because it is biodegradable.

In addition, it is recyclable and regarded as a sustainable building material. Its durability allows you to use it long before replacing it.

Dale Sayre