As specialists in off-site manufacturing for sustainable buildings, we think the creation of the construction systems you choose is worth considering. Here, we’ll look at what off-site manufacturing is and the way various building systems are made using this safe, speedy, supreme and sustainable method.

What’s off-site manufacturing?

The term off-site manufacturing has a few aliases. As well as being a Modern Method of Construction (MMC), it’s known as off-site construction, prefabrication and modular construction.

What sets off-site solutions apart from other methods of construction is that their construction elements must be:

  • Designed
  • Planned
  • Fabricated
  • Preassembled

— in a factory setting before transportation to and installation at the final construction site.

The key types of off-site construction include:

  • Volumetric systems
  • Modular systems
  • Panelised systems

Off-site manufacturing under controlled factory conditions is ideal for housing projects and larger modular builds, such as schools and hospitals. This is because many of the same components, meeting the highest possible quality standards, are needed.

Types of off-site manufacturing


This type of off-site manufacturing involves linking a series of large pre-built sections (modules) without the need of a superstructure. The main difference between a volumetric building module and other modular construction methods is that all six sides (one floor, four walls and one ceiling) are enclosed.

The internal fit-out, finishes and building services are pre-installed in the modules before they leave the factory. External fittings such as façades, claddings and roof treatments are usually installed onsite.

Volumetric building solutions are a popular choice for everything from commercial offices and hotels to sports stadiums and hospitals.

But they’re only really suited to regular building shapes so are less flexible when it comes to design. Also, the large pre-built modules usually need transportation via costly specialised vehicles.


With modular off-site manufacturing, individual sections are produced for assembly into a finished building at the final site. There are three basic module structures — four-sided, partly open-sided or fully open-sided.

Fully customisable and totally flexible, modular constructions can be installed fairly quickly and efficiently onsite. They can also be taken apart for relocation, refurbishment or re-use.

But their more open nature does make them less complete and reliable from the start, when compared to other off-site solutions.


Cross Laminate Timber (CLT) is made of layers of kiln-dried wood. These are glued at right-angles and the lightweight yet strong panels are cut to size in a controlled factory setting.

Often used as a more sustainable building alternative to concrete, CLT can form walls, roofs, floors and ceilings. It’s a good off-site manufacturing method for multistorey taller wood construction, balconies and stairs.

But, with no wall cavities added during manufacturing, the cost of electrics and plumbing services can increase the cost of the build.

Closed panel

A more complete structural element that’s fully finished in a factory setting before on-site assembly, an advanced timber closed panel building system is Streif UK’s go-to.

They usually consist of closed panel walls with floor and roof cassettes added to create a superstructure. Closed panel roof cassette systems are especially well-suited to mono pitched roofs and attic rooms.

All Streif wall panels come fully insulated and boarded, ready to be taped and jointed, for a more airtight building solution. Other closed panel finishings include internal wall linings, windows, doors, M&E cutouts and lightweight render (if required).

A crane is used to lift and fix the complete panels in place at the construction site. As no bolt-on services are necessary, a reduced installation team can quickly create a strong watertight structure.

Twelve members of the Streif UK off-site manufacturing production team standing in the factory

What are the benefits of off-site manufacturing?

Off-site manufacturing is the MMC choice for many UK building projects in the UK today. The benefits of closed panel offsite solutions, Streif UK’s method of choice for its award-winning sustainable building systems, include:


With almost everything fitted during the off-site manufacturing stage at a specialist factory, only basic installation occurs onsite with the help of a crane.

This cuts down the vehicles and machinery needed onsite, which reduces the chance of injury as well as congestion and pollution. For most of Streif’s detached houses, one lorry’s needed for each storey.

There’s no need for contractors to work from height or do any heavy lifting. And during the pandemic fewer contractors in close quarters meant the spread of illness was reduced too.


Using tried and tested materials from a trusted supply chain speeds up the off-site manufacturing process, which makes building projects move along efficiently.

Since most of the hard work is completed in the factory, the panels and cassettes arrive onsite in strict order. These are safely and quickly craned into position and fixed, making the building weathertight.

With fewer tasks to complete and no worries about weather conditions, there’s less time needed onsite. This means build programmes can be sped up, making offsite manufactured solutions savers of both time and money.

For example, a pair of Streif UK’s off-site manufactured closed timber panel semi-detached houses would take around four days to build. Whereas the installation of one of our education projects takes between eight and 12 weeks (depending on size, space restrictions and other specifications).

Supreme quality

Under factory conditions, manufacturing by a highly skilled workforce –– that’s continuously audited –– gives advanced quality control. This guarantees precision that’s hard to achieve with onsite construction. It also means everything is perfectly fitted and fitted out by the time it arrives for assembly.

For extra quality control before manufacturing, you can liaise with your building system supplier’s designers to plan everything to a t.


The use of ecologically sound materials manufactured in a way that lowers environmental impact and minimises waste makes for a sustainable building system.

Not only is timber one of those most sustainable building materials available, but off-site manufacturing really ups a build’s green credentials too.

Thermally efficient and airtight structures, created in factory-controlled conditions, achieve low U Values and reduce energy consumption. This not only makes them more comfortable to live or work in but also cheaper to run. Many Streif builds offer near Passivehaus standards and boast impressive levels of embodied carbon too.


If the benefits of off-site manufacturing for Streif’s advanced closed timber panel building system have piqued your interest, contact our technical team for more information.