Design Considerations for Terracotta Rainscreen Systems
Terracotta cladding is renowned for its design flexibility, distinctive colours, natural textures, durability and sustainability.
Its use can be traced back over 4000 years when it had extensive use in palaces, temples and statues. As a building material, terracotta has been used for thousands of years — and is likely to continue for thousands more.
Terracotta cladding is gaining a resurgence as natural facade cladding as architects and designers look at natural, textured and ecofriendly building materials that can add vitality to new building designs.
Refer to our article titled “How to Specify Terracotta” for design inspiration using terracotta as a cladding material.
Once a decision has been made to include terracotta cladding as your building façade, there are several aspects of design that need consideration, below are the key components.
Modern-day construction typically relies on two main methods to cladding a building in terracotta. These include rainscreen and precast concrete installations.
The most common method of installing terracotta cladding is as a rainscreen – the panels are installed onto an aluminium support system designed to support the cladding on the building's substrate.
This method creates a continuous external barrier made of the terracotta panels with overlapping joints; designed to drain water away from the cavity that lies behind panels.
Rainscreen façade is a two-level construction system which provides superior waterproofing, condensation control, long term durability and thermal efficiency.
Rainscreen system – designed to reduce water ingress and facilitate better airflow behind the façade.
Benefits of the Argeton Terracotta Rainscreen System
- Weather protection
- Preventing heat accumulation
- Moisture control
- Sound protection
- Thermal insulation
- Fire protection
When rain and wind force moisture towards the building, the majority is deflected by the terracotta outer layer, the primary weatherproof layer. The moisture that penetrates through the outer layer is then effectively managed through ventilation and drainage in the cavity between the primary weatherproofing layer and the secondary weatherproof layer. Rainscreen systems utilise airflow and ventilation to insulate buildings and minimize exposure and damage caused by the elements.
These rainscreen facades are designed to provide effective drainage and create convective airflow up the cavity. Warmer air within the cavity rises and draws cooler air in from the base of the wall, helping to keep the building mass cool as well as providing evaporative drying in the cavity for moisture and condensation management.
The Argeton Terracotta cladding system is a ventilated cavity wall system that acts as the primary weatherproofing layer preventing wind-driven rain from reaching the structural wall, allowing the wall cavity to breathe, and preventing mould build-up within the cavity. Being an open joint system, the air is able to circulate effectively through the joints so as to minimise pressure differences between the inside and outside cavities.
2. Precast Concrete:
The alternative method to Rainscreen installation involves fixing the terracotta to precast concrete panels. In this example a veneer is bonded onto large precast concrete units at the warehouse, once delivered to the site, these precast sections are then lifted into position and fixed to the building.
This installation method offers the strength of the concrete panels combined with the look of terracotta when viewed outside. This option allows for various profiles to be fixed to the precast sections; therefore, loss of design flexibility is not a concern.
The advantage of this method is the strength offered by the precast concrete panels and the speed of installation at the site. This is due to the individual terracotta panels being installed at the warehouse prior to going to the site.
However, care does need to be taken, as ongoing maintenance of the joins between the precast sections is required in order to ensure a weathertight second barrier is maintained throughout the life of the façade.
Across Australia, the most common installation method for facades is the Rainscreen method. Over the years the industry has become accustomed to working with this design with a resulting high degree of reliability and durability in the long term.
As an extension to cladding, terracotta is gaining a lot of interest in applications such as sunscreens.
Terracotta baguettes are designed to act as a sunscreen to reduce the amount of radiant heat striking the building while adding colour, depth and a distinctive modern appearance to any building.
Terracotta sunscreens are made as louvres and baguettes and are available in many colours, textures and shapes to provide an architect with full design freedom while maximising the thermal performance of the building.
These can be used in combination with terracotta panels in both internal and external applications to create unique visual effects, a uniform transition between elements, warmth, and maximum design flexibility.
Argeton Barro profile is available in various shapes and colours.
By reducing the amount of radiant heat reaching the building, terracotta sunscreens reduce the amount of solar head gain through the façade and into the building, assisting to reduce energy use and environmental impact of the building. Louvres can be positioned to block radiant heat during peak summer months and allow radiant heat through during the winter months.
Argeton’s range of Baguettes and Louvers offer:
- Vast variety of formats and colours.
- Non-fade/UV resistant.
- Hidden fasteners.
- No maintenance costs
- Fully recyclable.
- Resistance to aggressive substances.
One of the key characteristics of terracotta is low heat transfer – a feature that holds its heads and shoulders above many products in the market.
A typical 3mm solid aluminium had approximately 8-9kg or aluminium mass per M2. Depending on the type of terracotta cladding, the weight could be over $40 kg/M2. Terracotta’s higher mass value means that the thermal performance of a building is enhanced by using this product.
The heat transfer process through the building wall occurs by conduction, convection, and radiation. For example, in the daytime, the solar radiation hits the external all surface, a part of which is released to the outdoor environment and the other part if absorbed and conducted across the material. The heat transfer through the building envelope depends on several factors but the key one that is a benefit of terracotta is the thermal mass.
Thermal mass is the amount of heat energy that the object can absorb and store. In the building, thermal mass can significantly minimise indoor temperature fluctuation and reduce the heating and cooling demand.
Terracotta compared to lighter and thinner materials have a higher mass, a higher density which will moderate the heat transfer into the building.
The higher thermal mass of terracotta sees it able to offer over four times better resistance to heat transfer when compared to solid metal products. When coupled with a rainscreen installation method, terracotta cladding offers even greater thermal performance. The circulation of air within the cavity helps remove any heat transferred through the terracotta which assists in reducing energy costs.
Using terracotta sunscreens can assist by further reducing the amount of radiant heat striking the façade and help supercharge the thermal performance of the building.
Common terracotta installation is via the rainscreen method, where the terracotta panels are mounted onto an aluminium mounting system designed to offer durability, and airflow and significantly reduce the penetration of moisture into the cavity.
Argeton terracotta façade incorporates two installation methods:
- Vertical Method: – Ideal for large tiles where the vertical substructure can be spaced widely to reduce installation costs
Wall brackets and T-profiles are attached to the wall/substrate and create a structure for the terracotta panels to attach to the wall.
The Vertical joint profile profiles prevent water ingress between the vertical joins of the tile while the clips secure the tile to the T-profile substructure and fix the panels to the façade.
- Horizontal method: – Ideal for smaller tiles where the horizontal carrier rails are used to secure the terracotta panels to the substructure.
Wall brackets and L/T-profiles are attached to the wall/substrate and create a structure for the terracotta panels to attach to the wall.
The Vertical joint profile profiles prevent water ingress between the vertical joins of the tile while the clips secure the tile to the horizontal carrier rail and fix the panels to the façade.
The Argeton system has been designed for simplicity, speed and durability. By creating a cavity behind the terracotta panels, you allow airflow to help improve thermal performance and moisture management.
Terracotta as a building façade offers great advantages over other building products which explains its use over several millennium and its increasing relevance in contemporary building designs today.
Key to this are the benefits of terracotta – these being:
- Durable and long-lasting performance
- Good thermal performance
- Low cost of maintenance
- Wide variety of colours on offer
- Not affected by fire like other products
- Wide variety of textures on offer
- Eco-friendly due to ease of recyclability
- Wide variety of shapes on offer
If you haven’t considered using terracotta for your cladding – you are missing out on a lot of opportunities to take your building design from ordinary to extraordinary.
No other product can boast the tenure as a building product that spans several millennium, be contemporary and offer characteristics that are still relevant in today’s building requirements.