An interior renovation project is not just about choosing a paint color or flooring. Behind each service lie technical, regulatory, and budgetary constraints that determine the success of the project. Mastering these parameters in advance avoids rework, extra costs, and unpleasant surprises upon completion.
Technical Diagnosis Before Interior Renovation Work
We recommend never starting a renovation project without a prior structural diagnosis. The nature of the building (traditional masonry, wood frame, reinforced concrete) determines the possible interventions: opening a load-bearing wall, reinforcing the floor, adding heavy partitions.
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A punctual destructive survey allows for checking the condition of embedded networks (electricity, plumbing, ventilation ducts). In older buildings, lead pipes or fabric wiring require complete replacement, which significantly alters the budget.
Since the Climate and Resilience Law and its implementing decrees published between 2023 and 2024, work impacting the energy performance of a home classified F or G requires a regulatory energy audit before sale. This obligation directly concerns interior insulation, the replacement of windows, and modifications to glazed surfaces. Even for a project aimed at aesthetics, we observe that energy considerations are now systematically included in the specifications.
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To assess the extent of services suitable for your situation, the work proposed by Deco Asaiss covers a wide range, from demolition to decorative finishing.
Insulation and Ventilation: The Technical Foundation of Sustainable Renovation
Interior insulation is the most underestimated service in renovation. Poorly installed thermal insulation (thermal bridges at wall-floor junctions, absence of continuous vapor barrier) degrades the overall performance of the home and generates issues: condensation, mold, persistent thermal discomfort.
According to the Ademe survey published in 2024, the share of mixed renovations (aesthetic and energy) has significantly increased since 2022. Households renovating their interiors are increasingly integrating an energy dimension, even when the primary motive is comfort or decoration.
Controlled mechanical ventilation (CMV) must be sized according to the habitable volume and the number of wet rooms. Replacing a self-regulating single-flow CMV with a hygro-regulating type B improves air renewal without increasing energy costs. This aspect, often overlooked, is crucial for the longevity of all other finishing work.
Commonly Used Insulation Materials
- Glass wool or rock wool in semi-rigid panels, suitable for metal frame insulation. Good performance/cost ratio.
- Bio-based insulators (wood fiber, cellulose wadding) for projects prioritizing summer comfort and natural humidity regulation.
- Sprayed polyurethane, reserved for situations where the available thickness is very limited (converted attics, underfloor areas).
Kitchen and Bathroom Renovation: High-Impact Areas
The kitchen and bathroom account for the majority of the budget in an interior renovation project. These two rooms combine technical networks (cold water, hot water, drainage, electricity, ventilation) and specific regulatory requirements.
In the bathroom, the NF C 15-100 standard imposes safety volumes around water points. The choice of an ultra-flat shower tray or a walk-in shower modifies the reservation height in the floor and may require raising or redoing the screed.
In the kitchen, the positioning of the activity triangle (sink, cooking, refrigerator) remains a crucial functional criterion. We observe that custom projects incorporating a quartz or Dekton countertop increase the durability of the layout but require structural reinforcements to support the linear load.
Points of Caution on Finishing Work
Large-format tiles (slabs larger than 60 x 60 cm) require a very high level of flatness and double bonding. A poorly prepared substrate can lead to detachment in the medium term.
Stretch or suspended ceilings allow for recessed lighting and conceal networks but reduce ceiling height. Below 2.40 m after installation, regulatory habitability may be questioned.
General Contractor Formula or Direct Management: Decide Based on Project Scope
According to the 2025 barometer from the Order of Architects and UNAID, individuals now prefer turnkey and general contractor formulas for medium to large-scale renovation projects. This method of intervention combines design, coordination, and execution under a single point of contact.
Direct management (lot by lot) remains relevant for projects limited to one or two trades. However, it requires a good understanding of task scheduling. For example, having the plasterer come before the plumber can lead to costly rework.
- General contractor: a single global quote, a controlled schedule, a single responsibility in case of defects. Suitable for renovations involving more than three trades.
- Independent project management: the interior designer coordinates the craftsmen without executing. Relevant when the project requires a strong aesthetic or heritage dimension.
- Direct management by the individual: savings on coordination fees, but increased risk of delays and non-compliance if the schedule is not strictly adhered to.
The choice between these formulas depends as much on the available budget as on the technical complexity. A project involving demolition, structural work, and custom finishes almost always justifies professional support.
Regardless of the chosen method, drafting a detailed quantitative descriptive (DQE) before signing the quote remains the best protection against unanticipated amendments. This document lists each service, each material, and each quantity, line by line. It transforms the quote into a verifiable commitment upon project completion.