What is modular construction?
Modular building types in the UK were conceived a hundred years ago at the end of World War I when steel and aluminium factories needed new sources of work, and there was also a housing shortage. Many housing prototypes were designed, though hardly any used. Another surge came after World War II when timber and concrete were also considered.
Many houses, schools, factories and clinics were built quickly and well, and lasted. I myself was brought up in a prefabricated timber house donated by the Norwegian Government after the war and it’s still going strong. However, the partial collapse of Ronan Point, a precast concrete residential tower block, gave modularisation a bad name, and only small numbers continued to be built.
Modular numbers are still small. In 2009 only 3% of all construction was prefabricated. It’s difficult to find today’s figure, but it seems to be around 5%. Now there is a growing desire and a strong business case in that sector to increase this to 25%, but much change is required in the construction industry to make this happen.
Off-site construction, prefabrication, modularisation – there are several names covering the same theme. These range from small elements of a building, which can be brought to site and assembled quickly, to whole room modules. Sometimes these modules are finished on site, but more often they are finished in the factory complete with services, furnishings and equipment.
They tend to use dry construction elements that can be quickly assembled, rather than wet elements, which need time to dry and hence take longer to assemble.
The off-site assembly could use anything from metal or timber studs and precast piles to toilet and kitchen pods. Floor, roof and wall cladding panels and whole room modules can be designed for hotels, apartments, student residences, and healthcare.
Why not more modular buildings?
Although the UK still lags behind the US and some European countries, an appetite seems to be mounting and the momentum has reached a tipping point due to the huge housing demand and the realisation that the benefits far outweigh the negatives.
The sector is still very much in its infancy despite being around for decades, but there are some amazing examples around the UK which are helping to dispel some of the myths and break down the stigma that comes with modular buildings. Often thought as a cheap solution with no character due to their repetitive look and clinical aesthetic, however this is no longer the case.
The prime reason for the delay is that the majority of the construction industry is slow to change, and there is not enough incentive to change, though this won’t always be the case as the industry becomes ever more sophisticated and digitised. The speed of change for those leading the charge at the cutting edge is staggering. They will be in the pound seats as off-site takes a bigger chunk of the industry, and will have the intellectual property and specific systems to become more sophisticated as they are fine-tuned after each successive build.
Investment companies are now buying into the sector. When this happens, it’s a positive sign that there is change, which will hopefully encourage the hesitant to make the considerable move out of their comfort zone. The change should not be underestimated. New software and technology, training and up-skilling, all require investment. It’s a bold jump, but the risks are reducing every day.
There have been off-site companies set up that have folded due to lack of demand, which has been unfortunate. On the plus side, failures can bring about a more collaborative approach to find and forge partnerships to help spread the work load and risk.
Governments are setting off-site construction goals for public buildings, which may be slightly over optimistic, but it’s a good sign. Regulation changes and contracts for off-site construction have been put in place with various guideline documents available.
Profit and speed together have made off-site very viable, and in some eyes almost compulsory as a way forward.
- DfMA – Design for Manufacture and Assembly
- MPBA – Modular and Portable Building Association
- CfSH – Code for Sustainable Homes
- OSM – Off-Site Manufacture
- Design for deconstruction
Can it work for small developments?
As a developer construction-managing 20 residential units per year in-house, what could be the benefits for you? Using the statistics commonly used in the sector, it would mean you could probably build four developments over three years rather than three. This is a conservative estimate: due to the quick construction time it could even be five.
It’s likely a 10% cost saving could be made on each build, and possibly as much as 20% once your procurement systems have been fine-tuned, particularly if you have invested in iteratively fine- tuning the end product.
If these two huge incentives weren’t enough already, there are many other advantages. As the modules are built off-site, several trades are brought under one umbrella/contract. The site works can be prepared by a separate team/contract. The modules are then assembled on site and finished by the off-site specialist, and the site landscaping can complete the project.
A smaller developer wary of the risk could reduce it by undertaking a small development to test the water, or form a joint venture with an off-site specialist. Either way, there needs to be a learning curve and there will undoubtably be hiccups along the way.
There are likely to be less delays as the majority of work is carried out undercover and this tends to be more productive. Units are assembled to a higher standard. Material waste can be minimised. The health and safety benefits help all concerned, as less time is spent by personnel on the actual building site.
Forming a partnership with a suitable off-site manufacturer to deliver the required units could be used to your advantage. Your own staff can be trained and up-skilled in advance prior to testing the water with your first development.
Fig 1 – Modular Building Institute
It should be noted that this is becoming a specialist field. Surrounding yourself with a team well versed in this type of construction would not only be invaluable but essential to a successful project.
There are three main types of off-site construction which use the following materials;
- mass timber construction
- precast concrete
The approach adopted for each site could be different. This is also dependant on the site location. If it’s an urban site, there is a greater chance of a basement being required and that access to site could impact on the size of panels /modules that are delivered to site.
If it were me, I would try to cut down or eliminate all wet trades as much as possible, only using precast concrete in the ground for piling and foundations, and possibly lift shafts.
Timber, steel and concrete all require energy to make and procure them. However, only timber has a renewable sustainable source and hence I would adopt mass timber – although there are benefits with steel on high rise.
As an architect, I would be looking to design all the residential units as modules and bring them to site fully fitted. From a design perspective, the layouts need to be carefully planned so they can be used on future developments. To break any modular feel, the common spaces, building base, and façades can be articulated to “appear” bespoke. The use of materials, particularly cladding, can be effectively used to vary and articulate the building façade to achieve the intended design look.
Pros and Cons: are there really benefits?
The pros outweigh the cons considerably. Obviously the design team, in close collaboration with the specialist, must develop the level of detail, co-ordination, sequencing, and procurement. This is a positive for the development, as practically everything needs be considered and anticipated prior to pressing the green light to go into production.
An off-site-supplied site looks very different to your traditional site where every millimetre of space is used. Being less cluttered helps health and safety on site, and a shorter duration means less noise pollution for surrounding neighbours. There is also less traffic to and from the site. I like the fact that a higher level of accuracy can be achieved. Acoustic, fire and thermal performances can now be achieved and superseded.
There are a few Cons, as mentioned – mainly the upfront investment, but more and more industry players are forming partnerships. Some sites may appear to preclude an off-site approach, but with the right team, I believe off-site will always have a solution. Without a quality architect there is also a chance that the design may not meet the perceived level to satisfy the market criteria.
There is nothing new about this specific building type, but the design needs to be carefully considered from day one, thoroughly detailed and planned. There are many organisations working in this field now and there is also lot of information available.
Current and Future trends
Those already engaged in modular construction predict that modular could be 25% of the construction market in the coming years. Personally, I think it will be well beyond 2030 before this becomes a reality and even then, it would require a huge change which I am not sure is possible.
At the moment, the time is right for those in the industry start assessing seriously where modular is going and the benefits that come with it. If contractors and specialists leave it too late, they may have difficulty catching up once it has taken off.
Partnering and joint ventures are becoming more popular as a way to manage the peaks and troughs of demand. Further down the line, it’s envisaged that there could be networks of production factories across the country, highly managed to ensure workflow is spread evenly. The benefits would bring work locally to communities rather than in one or two locations.
The need in the residential market is providing a major opportunity. This is probably where we will see the biggest changes. They have already started and I suspect that modular construction will keep growing steadily, particularly if there is need and a market, which there is in most countries.
In the coming years, I also feel we will start to see complex building types wholly procured using off-site building methods. There would seem to be an opportunity here, as major projects can often take years to build and if they are in urban areas, the build time can be negatively affected by the congested nature of urban spaces. Often requiring other services to keep running and remain open, such as roads.
I also don’t see why modular can’t be used for any building type.
Of the three types, mass timber is showing itself to be very versatile and several stunning design projects have recently been completed showing that design is not restricted by a modular approach, let alone timber. Due to its ace card status as a truly sustainable product, I see the timber market growing more than the others, though the market share is difficult to predict.
Bamboo has been spoken about in the past, but seems to have fallen away. As the material grows so fast, it can only be a matter of time before its benefits come to the fore again.
Regulations are being revised to accommodate these building types. Local authorities are beginning to change regulations to also allow the use of mass timber now that its benefits have been proven – particularly the fire and acoustic benefits.
Lastly, I have mixed feelings about using the word “modular” as it gives the impression of being “boxy”, though it’s still a wonderful word which conjures up modern, cutting edge and the future.
Image credit: iStock.com/vavit