Can CAD help construction build, build, build?

Chris Powell, Sales Director at Pasquill, considers how design technologies and off-site modular construction go hand in hand to improve the quality and quantity of homes built in the UK

For decades, we've struggled to build enough new housing to keep pace with demand. Many experts feel that off-site construction is the best way forward, especially in light of the Government's commitment to build 300,000 new homes a year.

This forms part of the Conservatives' New Deal, a £420 million injection in the construction sector which aims to reduce the time to build new houses by 50%, with a focus on accelerating the adoption of modular construction.

Off-site and prefabricated manufacturing techniques are gaining momentum as a means to reduce wastage, inefficiencies and delays on site. But off-site manufacturing (OSM) is not a new concept. We can trace the practice of assembling buildings away from the construction site as far as the Romans. In the 1900s, we saw the development of kit homes in the US and, here in the UK, the post-war period took advantage of prefabrication to help address housing shortages.

In fact, when many people hear the word prefabrication, they think of these (somewhat poorly constructed) temporary homes from the 60s. But off-site manufacturing has come an incredibly long way since then, not least because every element of the process has been refined and enhanced by technology.

From design software that can map out an interactive 3D model to manufactured products accurate to within fractions of a millimetre, these modern methods of construction (MMC) improve cost predictability, the quality of the final build and allow us to put up homes at speed without impacting on the finished product.

Combining CAD technology with the manufacturing benefits and speeds up every step of the build, from end to end. This is demonstrated by the fact that we are finding clients requesting their drawings earlier in the build timeline, long before work begins on site. The use of 2D and 3D designs naturally help them to see the visual realities of their concept and it's spatial planning before further financial resources are committed. From the earliest stage, these drawings can also generate accurate costs for the build, which are generally much more stable when OSM is used.

CAD is generally much quicker than traditional freehand drawing, particularly when you factor in the time saved in the amends process or the ability to create different scale models at the click of a button. Software can also help to coordinate the different disciplines involved in the design and eliminate any possible clashes, resulting in a reduction in remedial work on-site. Furthermore, designers can conduct structural analysis and energy calculations through simulation within the 3D model environment.

We use the MiTek suite of software including Pamir, a fully integrated CAD layout and engineering software allowing us to design our products to the very latest design codes, and WoodEngine, the industry leading timber frame detailing software. Both offer powerful links to numerous other packages to allow for complete BIM integration.

CAD designs can be incredibly useful in speeding up planning applications too, providing planners with visual context in a more intuitive way. For example, 'a right to light' concern can be quickly answered using 3D visualisations, GIS mapping and daylight simulation.

At Pasquill, we specialise in OSM timber frame elements, such as roof trusses and floor cassettes. As each product we design and manufacture is bespoke, we don't offer standardised BIM catalogue objects. However, finished designs can be packaged in file formats that integrate them with our client's central model, allowing us to work in partnership with other suppliers. This also allows the client complete control and overview of the build, with the ability to cut down walls, make easy alterations, import elements such as electrics or heat recovery and highlight potential clashes in the building.

Further efficiencies can be found with a design for manufacture ethos, which we implement across all our sites. A lot of machinery accepts instructions from CAD drawings, resulting in computer aided manufacturing (CAM). For example, we generate files from the design models that dictate how we set up equipment, such as timber CNC saws, presses or the laser on the manufacturing benches. Using these methods we maximise the use of material, minimise waste, speed up the manufacturing and improve accuracy with products designed to closer tolerances than their traditional counterparts.

This process also enables much better oversight of quality control. The dry, well-lit surroundings of a factory and checks throughout the entire manufacturing process ensure any issues with quality are detected and rectified.

Finally, when it comes to delivery, our CAD technology tells us the overall bulk that needs to be delivered and how it can most efficiently fit into our lorries. The plans are also provided to builders so it can be installed with ease. Lovell Homes has previously described our products as like building with Lego!

Manufacturing houses in a factory is a safer environment than building on site, less exposure to sun, rain and wind. Minimal site traffic and working from heights is minimised (the main cause of fatal accidents and injury on site). OSM, facilitated by CAD, makes construction safer through the mitigation of many site-based risks.

Building this way also means that fewer personnel are needed on site, addressing the ever-growing construction skills gap. Tradespeople will always be important, and they can also be accommodated in a factory setting, but as a sector we must also turn our attention to training the next generation of designers. Through better design using CAD and the manufacturing of houses in a purpose-built factory, costs can be reduced through efficient use of materials and sustainability targets can be met all while promoting a safer way of working.

In addition to speeding up the large-scale building of much-needed homes, OSM is also a valuable tool for bespoke self-build projects or to help ramp-up production of smaller builds which are rising in popularity, such as garden rooms. Use of CAD and OSM provides the same benefits: standardising costs, quality and predictable timelines.

For self-builders in particular, it can provide confidence and allow them to drive forward with new and exciting designs that would have been unaffordable or unachievable before OSM. For example, Pasquill used MiTek to design and manufacture an intricate 16-sided roof with a central skylight for a completely circular holiday home in Scotland. This took numerous revisions and several senior designers working together to build a model that would support a sedum grass roof three times the weight of a standard tiled roof. When the time came for installation, the roof was assembled without issue by a few builders in rural Scotland.

There is unlimited potential in the construction industries that will be untapped as these manufacturing and CAD design technologies grow together. The near future promises widespread use of 4D and augmented reality design models, while one of our Saint-Gobain sister companies, Weber Beamix, created Europe's first 3D printed house. But for now, in my opinion, OSM is the very best way of helping the sector meet its housing targets.

Pasquill is part of the Saint-Gobain Off-Site Solutions Division, which includes brands Scotframe, International Timber and Roofspace Solutions. Visit: to find out more about how our design technology and OSM capabilities can help deliver quality build projects on time and on cost.