VR & 3D Modelling Key To Sterling's HexxHome | Greater Use Of Digital Technology

Digital technology is helping to deliver Sterling Services’ new offsite manufactured housing concept.

With a government drive for increased offsite manufacturing and standardised components, together with greater use of digital technology, the arrival of Sterling Services’ precast housing system looks perfectly timed.

HexxHome uses pre-fabricated panels made from high-strength concrete. These are based on hexagonal forms which allows multiple configurations to be generated, resulting in the creation of many different building layouts, from studio flats to five bed houses. The precast components and housing designs are modelled in 3D using Autocad, which generates a VR (virtual reality) visualisation allowing designers, constructors and customers to ‘walk though’ an individual property or even a whole street of them.

“We see potential for HexxHome in the affordable housing sector as it is a robust, high-performance building with strong whole-life credentials” says Chris Bell, Sterling Services managing director.  “We have a small scheme of four flats which has gone into planning with South Hams Council in Devon and we also have interest from the self and custom build market.”

Conceived in 2014 and patented in 2017, the HexxHome system allows construction professionals or self-builders to design their home from standardised components without having to worry about the structural engineering, explains Phil Bent, HexxHome business manager.

“The pre-engineered slabs can fit together to create almost any shape of building,” he continues.  “We have an LABC/Premier Guarantee warranty for up to three storeys, but the structural capacity is there for multiple storeys.  The slab edges have sloping, rather than 90-degree angles so when the wall panels are tied together, there are no lateral forces and they act as a composite I-beam.

“The ground floor slabs sit on piles or strip foundations; piling is the preference as that saves on additional concrete beams in the substructure. The layout is normally identical on all floors to carry loads down through  the structure.”

The panels use common mixes and reinforcement as Sterling Services eventually wants to license the component parts to other manufacturers. “We include fairly standard architectural mixes which we use in the Sterling Services factory in Taunton,” says Bent. “GGBS or PFA cement substitute  can be used but it is extremely important that we build to British and Eurocode standards.”

Once the monolithic shell is constructed, insulation is fitted to the slabs followed by a batten void for the varying services and finally plasterboard. The wall panel dimensions, typically 2.9m high by 2.6m wide, have been designed to minimise cutting of insulation, plasterboard and skirting boards.

“The idea is to keep it simple, so that it is straightforward for a self-builder as well as an industry professional,” says Bent. “A three-bed home can be assembled using a mobile crane and can be watertight in as little as two to three weeks.”

The wall panels can be faced in brick slips or various concrete finishes, which typically takes place in the factory, while timber facades can be attached on-site using cast-in sockets.  The rooves are flat, structural slabs, with a BBA approved synthetic roofing membrane; this can be used to support solar panels or be used as an amenity space. “The style of our offering is more contemporary than traditional,” Bent adds.

The concrete construction, along with the roofing membrane and mastic joint sealants, means exceptional airtightness and strong thermal performance with ‘U’ values of just 0.12 W/m2k.

“The building fabric is at Passivhaus standard and the acoustic insulation is also fantastic,” says Bent. “Use of dry joints also makes it easy to rearrange the building layout - for example, if a family wanted to extend their home.”

The turnkey cost of a HexxHome starts from £1,650 per sq m and the various design options can be visualised by the prospective clients using Sterling’s VR system.  

During 2019, Sterling Services will develop its digital approach further by partnering with suppliers who also work in BIM.  “Companies like Velux and Polyroof will provide us with BIM products which we can drop straight into our model,” says Bent.