Off-site modular construction: challenges, developments and impacts on control offices

Off-site construction is an innovative construction method that allows building components to be manufactured and pre-assembled, in the factory, for installation on the final site.

Off-site construction and its benefits for the sector

It comes from DFMA - Design for Manufacturing & Assembly -, “Designing for Prefabrication and Assembly”. This modern construction method integrates all building trades into an industrial process and requires the entire sector to reinvent itself and adapt its methods.

Growing rapidly, off-site construction will account for 2030% of buildings built worldwide by 20 (source: McKinsey). This growth can be explained in particular by the scarcity of skilled labour, the rise in the cost of construction and claims, the lengthening of delays on construction sites and the growing awareness of the environmental impacts of the construction sector. .

The main differences between construction methods

The traditional construction

Economic

Delays in delivery are on average 5 months for nearly 30% of real estate programs delivered (source: UFC Que Choisir, 2017).
The increase in construction costs is +5,5% between 2019 and 2021 in France (source: INSEE, 2022).
The cumulative drop in productivity on construction sites has been 19,3% since 2001 (source: Xerfi).

Environmentally Friendly

Concrete represents 8% of global CO2 emissions (source: Guardian, 2019).
The equivalent of 1,5 billion euros of products and materials not used on construction sites are thrown away, or at least stored each year without being listed by the 400.000 French construction contractors.
Claims have increased by 75% in 10 years (source: SMABTP).

Off-site construction

Economic

The productivity of a worker on a conventional construction site corresponds to 20% of his time, compared to 80% for off-site construction (source: Aalto University study).
Lack of quality in construction costs almost 10 billion euros per year, or around 10% of the sector's turnover (source: Agence qualité construction).
Workplace accidents are reduced because the factory working environment presents less risk.

Environmentally Friendly

The transport costs are divided by 5 because the materials can be stored in the factory, unlike the construction sites where they are delivered drop by drop and where they can degrade. In addition, the workers do not need to move on each operation.
Resources are better managed and sorted, which reduces waste.
The use of renewable or recyclable materials is facilitated: wood, steel, biosourced materials, etc.
The recycling of materials is better optimized thanks to the dismantling of elements and modules or their reuse in another place and sometimes for a completely different use.

Off-site construction and RE2020

Building off-site significantly reduces the carbon footprint of structures, which makes this construction method a major asset for the implementation of RE2020.

Entering into force on January 1, 2022, RE2020 is the new environmental regulation that replaces the 2012 thermal regulation (RT2012). One of its objectives is to limit greenhouse gases generated by building construction and energy consumption.

From a project approach to a product approach: the impacts on control offices

While the development of off-site construction in France is in its infancy, this particular construction method is an opportunity to be seized for the entire sector, including technical control offices. All these developments are leading to a profound change in working methods... and require the commitment of all players!

The evolution of the mission of the technical controller

The role of a technical control office is to contribute to the prevention of technical hazards in the construction of works.

As part of an industrialized project, the technical controller is more involved in the design phase. Its role is to verify the feasibility of the design, the conformity of industrial solutions, but also to detect non-traditional or innovative techniques requiring special ATEX-type justifications.

In the execution phase, the technical control mission on the site is supplemented by off-site inspections in the factory. During the construction phase, checkpoints specific to this construction method are carried out.

The technical controller must take into account the specificities of this construction method, and understand its philosophy to best fulfill its main mission of preventing risks and hazards.

For Elia Abou Chaaya, Director of Off-site Activity at BTP Consultants: “Off-site construction is revolutionizing the sector and impacting all those involved in the act of building, from public authorities to the end user, including insurers, designers and control offices. Currently, the classic rhythm of a technical controller, even if it intervenes at all phases, is not adapted to industrialization. It's a whole state of mind that evolves, moving from a project approach to a product approach. Through this standardization approach, builders or project owners seek to optimize time, material costs and intellectual services. The technical control mission initially planned for a “project” is therefore adapted to bring more added value in the design phase and is supplemented by factory checks. »

Changes for the SPS coordinator

The SPS coordinator is involved in all phases of a construction operation and has the role of assessing the risks on the site and subsequent interventions on the structure.

On off-site construction projects, the SPS coordinator adapts his vision to take into account the risk of accidents controlled in the factory, the reduction of the construction phase and the special treatment of deliveries and the method of assembly of the modules. In addition, subsequent interventions on the structure are better defined and better controlled than in a traditional scheme.

The need for changes in the regulatory arsenal

Standards, rules and validations of “non-traditional” techniques lengthen lead times and can complicate the completion of a project. France must know how to innovate in relation to the current regulatory framework. The concepts of building safety must be reviewed and the rules of the art of all trades must be rethought around a process of industrialization of construction.

How BTP Consultants moves the lines of off-site construction?

For Roland Le Roux, President of the BTP Consultants Group: “Aware of the advantages and potential of off-site construction in France, BTP Consultants positioned itself very early on as a pioneer in technical control for this type of construction. We have created a department dedicated to off-site projects and formed a national network of around twenty employees capable of responding to the specificities of these interventions. Through our support for the Campus Hors-Site launched by Pascal Chazal and the organization of events on the subject, we are committed on a daily basis to its democratization in France. »

The control office is a key player in a construction project, and its role is particularly central in off-site construction projects which sometimes call for innovative techniques and methods.

For Pascal Chazal, Founder of the off-site Campus: “BTP Consultants is creating a module dedicated to technical control on the off-site campus platform. Its involvement alongside the various site stakeholders, its understanding of the industrial approach and its ability to adapt to it are all essential factors for the technical control mission to be at the service of an off-site construction project. success. With the industrialization of the concept and the reproduction of projects resulting from the same design, the technical inspector has more and more control over his verification and control process. It adopts an industrial approach and thus optimizes the time spent during the production. »