23 May 2025
The Allure of Modular
The Allure of Modular - a handy guide to the risks, to help you through your modular journey…
Let's face it - design and construction is hard. It's expensive to plan, has high risks of delay, escalating budgets and, worst-case, regulatory breaches and prosecution. Compounding the stress, public sector clients are faced with budget cuts, resource constraints and an ever-increasing regulatory compliance burden.
Within this anxious reality, modular construction is dealt a marketing ace – they can offer to make things easier, to take the risks away: clients relax, don't worry, we take care of everything... off-site (out of sight, out of mind?).
Potential Benefits and Risk Awareness
It is true that for some projects modular has advantages and for these reasons Floyd Slaski Architects remains a keen proponent, when the benefits are clear. We enjoy engaging with both clients and suppliers to deliver successful modular schemes.
The aim of this article however is to highlight the risks of modular, to raise awareness and increase chances of realising the benefit, including:
Reduced site logistics: Less on-site activity. For sensitive, live environments (like hospitals), this can be a big plus. (but remember most modular builds include substantial on-site works)
Less weather risk: Off-site fabrication isn’t held hostage by rain or snow. (but check how the modules are affected by rain during delivery and before the roof and cladding is complete - check the modular company is responsible)
Environmental benefits: Reduces waste and lower carbon emissions. (check credentials in this respect, eg where are the modules fabricated?)
Programme and cost: When the brief is tight and the team is right, modular can deliver faster and cheaper. (but can be more expensive and take longer if badly managed or if the project isn't suited to modular)
Repetition = efficiency: Benefits when module layouts match the design brief, like hotels (but check what compromises are needed to fit a standard module size, and if maximising the module width, check transport viability)
Government Support and Perceptions
Turbo-charging this modular marketing gold, and perhaps with envy of success in other parts of the world, the UK government spent years actively encouraging and even funding modular (Modern Methods of Construction / MMC), instilling in many clients' minds that MMC is preferable - faster, lower cost, lower hassle, lower risk, lower carbon. MMC - a badge of honour!
This has given clients a false sense of security, and despite many failed projects and modular business going bust, enthusiasm for modular remains high.
Avoid Temptation
We advise our clients to proceed with caution, and especially to avoid the temptation to enter a modular contract on the basis that the project needs to be delivered quickly.
Projects without watertight Employers Requirements (ERs) risk inflated costs and delays leaving clients in deep water with no way out.
Legal and Compliance Responsibilities
Clients must make suitable arrangements for planning, managing, and monitoring a project so it complies with all relevant requirements.
Appointing a modular company, even if sold as 'turnkey' does not in itself substantially discharge this duty. The client must have robust project implementation and execution plans including confirming (not limited to!):
Project roles and responsibilities
Procurement route
Programme - design, assessments (e.g., BREEAM), approvals and construction for both modular and non-modular elements
Golden thread information and its requirements for the project, including BIM
Competencies of the Principal Contractor, Principal Designers and Designers
Assessing Modular Competency and Scope
Modular companies provide design and build services. In practice, they must take on the legal Principal Designer duties (must be a direct client appointment). If they resist, then their competence must be questioned.
Clients must be satisfied that the modular company has the competence to take on the design, specialist design, off-site construction and on-site construction (it is never fully off-site).
Management Contractors or Off-Site Builders?
Many modular companies operate as management contractors, where design and fabrication is sub-consulted and sub-contracted. Others have some of their own in-house designers and fabrication capability. Either way, their set-up needs to be understood, and competencies need to be checked. How many similar buildings have they delivered? Get references!
Regulatory Risks and Misconceptions
Remember too that modular does not reduce building regulations compliance risk. A common misconception is that modular means standardised, pre-checked, certified construction. This is not the case.
Example - Fire Safety Risks
Generally, modules are not fire tested as a whole; they rely on compliance evidencing in a traditional manner, compiling piecemeal certification for individual systems and products. This can be more difficult in modular, for example where floors can be lightweight, often with interstitial voids between levels and in vertical joints. Demonstrating the fire safety of penetrations through lightweight floors can be difficult. Fire stopping at floor level may be impossible; fire rated shafts may be the only option, but how is the shaft supported?
We would recommend concrete floors, certified to achieve the necessary floor to floor fire separation, in addition to assisting with acoustic and vibration control.
Future Adaptation and Compliance
Consideration of the viability of future maintenance and adaption is essential – consider how will future project compliance be evidenced? Adaptation can be difficult due to the modular grid and compliance risks.
"But It's Only Temporary!"
Warning: if your planned modular is considered 'temporary', perhaps built as decant space, don't think there are any regulation short cuts. The same rules apply: fire and structural safety, energy efficiency, accessibility etc.
Programme Planning and Procurement Routes - Rush and Regret
Entering into contract before planning approval is risky and don't forget BREEAM may be a requirement! Early low cost BREEAM credits can easily be missed, resulting in more expensive credits and design changes. Rushing reduces your negotiating position.
Split Procurement
Procurement, design and site coordination complexities and risks: modular projects usually require the appointment of two separate Principal Contractors – infrastructure /enabling and modular. Modular firms may have limited experience of foundations, drainage, external works, complex MEP, cladding interfaces and link buildings.
Roles and responsibilities, interfaces and programme (sequencing) are all critical. The infrastructure and enabling contract cannot be accurately procured until the modular design is complete.
Hybrid Construction
Whilst typically refusing infrastructure /enabling elements, it is typical for modular suppliers to bridge offsite and traditional. The basic modules are constructed offsite, and the building services, finishes and envelope are completed on site, just like a traditional refurbishment. Sometimes little more than the structure is constructed off site. Know what you are getting!
A Single Tier 1 Contractor?
Alternatively, the client can tender the whole project, say to a Tier 1 contractor, that can do the infrastructure, enabling and traditional construction as well as sub-contracting the modular component – but that comes at a cost, and erodes modular’s potential pricing advantage.
Financial Risks and Due Diligence
Remember the substantial upfront payment needed for the modular supplier to mobilise the factory, order materials and commence fabrication. Make sure the ER's are watertight before contract and before up-front payments.
Checking the financial standing of modular company is crucial, both because of the up-front payments and the precedent of modular companies going bust.
Careful Project Planning - No Shortcuts
Remember that a thorough briefing and design process can't be circumvented without substantial risk. A modular procurement route does not reduce the need for the design stage.
Modular isn’t a shortcut. It’s a method. And like any method, it needs the right people, the right preparation, and the right scrutiny.
Tailored Advice and Industry Engagement
At Floyd Slaski Architects we discuss our clients’ needs and help determine optimum procurement and construction methods.
Every project is unique and modular viability and benefits vary. It might be a clear decision, or might be a close call, where the input of the whole project team is needed to get a clear picture.
Further Reading