Interior architect or DPLG architect: what are the differences and which one to choose?

When preparing a construction, renovation, or design project, a common question arises: should you hire a DPLG architect or an interior architect? Both professionals work on built spaces, but their roles, skills, and legal frameworks are very different. Understanding these distinctions helps avoid mistakes in choice, optimize your budget, and above all, entrust your project to the right expert. Here is everything you need to know to decide with confidence.

What is a DPLG architect?

The DPLG architect, now replaced by the state architect diploma with HMONP certification, is a professional legally authorized to design a building and submit a building permit application. Their role concerns the building’s structure, project placement, regulatory compliance, and overall site coordination.

Hiring a state-certified architect becomes mandatory when the floor area exceeds 150 m². They intervene from the design phase to define volumes, materials, technical constraints, and compliance with urban planning rules. Their expertise covers new construction, major extensions, raising existing buildings, and heavy transformation of existing structures.

The architect also manages the construction work: coordinating contractors, controlling execution quality, and ensuring budget and schedule adherence. Their approach is comprehensive, technical, and regulatory, with significant legal responsibility.

What is an interior architect?

The interior architect mainly works on the layout of existing spaces. Their goal is to optimize volumes, circulation, light, materials, colors, and furniture to improve the comfort and aesthetics of a place.

Unlike the DPLG architect, they cannot modify the load-bearing structure alone nor submit a building permit application. However, they have advanced expertise in interior renovation, custom layout, and decorative enhancement. Their role is essential for transforming an apartment, rethinking a professional space, or creating a coherent and functional atmosphere.

Their work often includes designing plans, 3D visuals, selecting materials, furniture, and indoor lighting solutions, which are key elements in the perception of a space. To better understand this profession, you can read this dedicated article: what the interior architect profession involves.

The key differences between the two professions

The first difference concerns the legal framework. The DPLG architect is authorized to work on the building’s structure and handle administrative procedures related to the building permit. The interior architect mainly works on the layout and transformation of existing volumes.

The second difference relates to the nature of the projects. The architect mainly handles major projects: construction, extension, significant rehabilitation. The interior architect focuses on usability, aesthetics, ergonomics, and the atmosphere of living or working spaces.

Finally, their approaches differ: one works at the scale of the building and regulations, the other at the scale of daily experience and visual comfort. These two perspectives are complementary rather than opposed.

Which professional to choose depending on your project?

The choice mainly depends on the scope of the work. For new construction, major extension, or any structural modification, hiring a DPLG architect is essential, even mandatory.

For apartment renovation, house reorganization, workspace creation, or shop optimization, the interior architect is generally the most relevant professional. They improve functionality, aesthetics, and lighting quality without engaging in heavy structural changes.

In many projects, budget considerations also guide the decision. The interior architect often works on more targeted operations with controlled overall costs, while the architect manages more complex projects involving multiple trades.

Can you work with both?

Yes, and it is even common in ambitious projects. The DPLG architect designs the building envelope and ensures technical compliance, while the interior architect imagines living spaces, atmospheres, and layout details.

This collaboration results in a coherent outcome, both architecturally solid and pleasant to live in daily. It is particularly relevant for contemporary houses, hotels, restaurants, or office projects where user experience and visual identity are essential.

Conclusion

Choosing between a DPLG architect and an interior architect therefore mainly depends on the nature of your project. The former works on structure, regulations, and construction, while the latter transforms existing spaces to improve comfort, aesthetics, and functionality.

In all cases, clearly defining your needs upfront remains the key to a successful project. Understanding each professional’s role saves time, optimizes your budget, and achieves a result truly suited to your lifestyle.