Saudi architects turn to rammed earth for sustainable building

When Riyadh-based practice Syn Architects organised workshops on rammed earth construction recently, it was amazed by the level of interest. ‘We had participants flying in from Kuwait, and someone came from the UAE. We were quite surprised – people drove in from the eastern province of Saudi three hours away,’ says Nojoud Alsudairi, co-founder with Sara Alissa of both Syn and vernacular architecture researcher Um Slaim Collective. 

Syn invited Austrian rammed earth expert Hanno Burtscher of Earthman to lead the workshops. The practice had worked with him on its recent Desert X rammed earth installation in AlUla, an immersive piece that slices through the desert landscape. He also oversaw the rammed earth construction on Adjaye Associates’ visitor pavilion, recently completed at King Salman Park in Riyadh. Adjaye is not the only international architect to use the technique on a high-profile contemporary building in KSA – Snøhetta incorporated 2000m² of rammed earth walls into its 2018 King Abdulaziz Center for World Culture (Ithra), and the technique is also a key element of the Diriyah Art Futures museum, recently completed by Italian architect Schiattarella Associati.

The Rome-based practice was keen to work with materials with a local connection. ‘When we started working in Saudi Arabia 16 years ago, we found a country which was strongly influenced by Western architecture. We wanted to work in a different way, with respect for the diversity of Saudi architecture,’ says chairman Amedeo Schiattarella, adding that rammed earth was a ‘great opportunity’ to express architecture.

Following on from Adobe

Certainly, the technique seems to be having quite a moment. The recent use of rammed earth can be seen in the context of a resurgence of interest in the kingdom’s earthen architectural heritage of adobe – and in particular the Najdi style – a building tradition using air-dried mud brick that was widespread until modernisation in the late 20th century. Meanwhile, adobe is a key material at Diriyah, one of the 14 ‘giga-projects’ proposed at the kingdom, alongside the important heritage site of At-Turaif in Riyadh. At AlUla in Medina province, Egyptian architect Shahira Fahmy has completed Dar Tantora The House Hotel as part of the practice’s restoration and rehabilitation of the adobe old town.

Unlike adobe, rammed earth is not traditional to Saudi Arabia. Characterised by distinctive strata-like horizontal lines, it is formed by earth layers compressed in temporary formwork, with wall thickness varying depending on whether it is loadbearing, and whether the mix includes stabilisers.

According to Professor Dr Khalid Alskait of King Saud University, an architect and masterplanner with an interest in natural materials and practical knowledge of rammed earth, the technique offers many advantages as a local material with a low carbon footprint and good thermal mass. It can also, he says, be combined with earth tube cooling techniques in desert areas.

‘In moderate desert climates, it’s certainly a good building material because it regulates humidity inside the building, keeps the building relatively cool in warmer days and warm in colder days, and will live long… But you need practical knowledge of how to do it. The moisture content, the soil mix and the ramming method are critical elements for successful building,’ he says. 

For Syn, rammed earth resonates with the adobe vernacular tradition while being more durable and offering the low-carbon benefits of local sourcing. The practice proposes to use it on schemes including a mosque for the Sports Boulevard giga-project in Riyadh.

‘We’re interested in using rammed earth as a re-use project,’ says Alsudairi. ‘We tend to use it a lot when there is the right amount of excavation happening… It has historical and cultural resonance: in the 1950s and 60s, our grandfathers were still living in adobe structures.’ 

Local and sustainable

Earthman’s Burtscher says rammed earth appeals to architects because it is sustainable, locally sourced and has the potential to help realise their visions. 

‘You can easily shape clean structures, clean lines, and it’s my understanding that international architects are looking into rammed earth as a great material for their designs because it comes from the area and so is super-sustainable.’

‘Most people love the layers but that’s subjective. One fact that isn’t subjective is the [thermal] performance,’ he says, adding that this has knock-on effects of saving on energy use and the cost of air-conditioning, and increasing the quality of the interior environment.

For Adjaye Associates, which used 6500m² of rammed earth walls for the King Salman Park project’s five pavilion structures, use of the material was inspired by the nearby Tuwaiq mountains and the idea of elements rising from the earth. The design was developed with Austrian rammed earth expert Lehm Ton Erde.

‘It was very important to use the geology and materiality of the limestone and clays. That’s how we came to use rammed earth, with pavilions coming out of the ground beneath a soaring roof,’ says project director Guy Parkinson, adding that it was important to bring these traditional techniques into a contemporary ‘Salmani’ style that avoided pastiche.

Making it mainstream

The project demonstrates one of the key challenges for more widespread use of rammed earth in the kingdom. Because there was no material reference for rammed earth in the local building code, original plans for loadbearing walls up to 14m high were revised to include a 200mm concrete core sandwiched between two 200-300mm walls of prefabricated rammed earth to comply with regulations. But even when used as cladding, rammed earth can still provide the thermal mass, and aesthetic and health benefits of a natural material.

At Diriyah Art Futures museum, Schiattarella Associati tested 25 proto-types before finalising the technique for a screen of rammed earth pillars up to 7m high, to mediate between the nearby ruins of the old town and the newbuild museum. The rammed earth was cast in-situ and stabilised with a concrete core.

‘It’s a fantastic material, but it is still in an open field of experimentation,’ says Andrea Schiattarella, adding that established standards for the mix and strength of material would be useful.

Another factor in the take-up of rammed earth is the training required for successful construction, according to Dr Alskait, who wants to see a ‘paradigm change’ in architectural and design education to teach more practical knowledge.

See more stories from the Gulf hereHowever, Burtscher, having trained a rammed earth construction team of 150 at the Pavilion with a few expert colleagues, rejects the idea that rammed earth is a difficult technique to convey, and expects to be on site again soon with another project in Saudi Arabia.

He believes there is potential for earth techniques in a broad sense to become part of mainstream construction – whether rammed earth walls and floors, or clay plaster. 

While the Adjaye pavilion uses pure earth, use of stabilising additives of between 6-12% is common in rammed earth construction. Burtscher considers this turns the material into something of an ‘eco-concrete’; he is concerned that clients may not always be aware of a consequential reduction in the carbon-saving benefits when using it this way.

Expert knowledge is vital says Reema Bin Rubaian, principal architect at RR Architects and Rammteck International, which was the first rammed earth construction company in the region when it was founded in 2017. 

‘We visited experts around the world and saw an opportunity to introduce rammed earth to the Saudi Arabia market, with a total service including engineering and architectural expertise,’ she explains, adding that while it is becoming more accepted as a material, a greater understanding of the required expertise is still needed.

‘One of the challenges is that it’s not included in the Saudi Building code. So we’re carrying out laboratory tests and working to introduce it as a building material,’ she says.