Why choose Avenir Renovations?
What is a lost attic?
An attic is classified as lost when it does not have the necessary characteristics to be converted without significant modification. It is also referred to as non-convertible attics.
Characteristics of lost attics:
- Industrial frame of the W type (trusses)
- Insufficient ridge height (less than 1.80 m)
- Roof slope too low (often less than 30°)
- Non-load-bearing or non-existent floor
- Absence of secure or accessible access
Despite these constraints, it is entirely feasible to make these attics habitable through specific modification or reinforcement work on the structure.
Steps for fitting out lost attics
Transforming lost attics into a comfortable living space is an ambitious project that requires method and expertise. To ensure a result that meets your expectations, each step of the fit-out is carefully planned, from the initial study to final delivery. Here’s how we proceed, step by step.
Solutions for converting non-convertible attics
Transforming lost attics requires the intervention of experienced professionals. Avenir Rénovations offers several options depending on the configuration of your home:
Replacing a W-shaped industrial framework with a traditional or scissor truss framework allows for the central volume to be cleared and frees up living space.
When the height under the ridge is insufficient, it is possible to consider a partial or complete elevation of the roof while respecting the architectural style of your house.
In some cases, a slope that is too shallow can be corrected by reconfiguring the slope, subject to urban planning permissions.
If the attic floor is not load-bearing, it can be reinforced to support a living load (partitions, furniture, circulation...).
We can create a hatch and a custom staircase, adapted to the available space and the intended use.
How much does it cost to fit out lost attics?
The fit-out of non-convertible attics involves heavier works than a standard fit-out. Here is an indicative table of costs, to be adapted according to the area, chosen materials, and technical constraints.
| Type of service | Average price including tax |
| Feasibility study + execution plans | 80 to 150 €/m² |
| Modification of framework (replacement) | 300 to 600 €/m² |
| Roof elevation | 800 to 1,200 €/m² |
| Reinforcement or creation of load-bearing floor | 70 to 110 €/m² |
| Installation of roof windows | 800 to 1,200 € / unit |
| Custom access staircase | 2,500 to 4,500 € |
| Complete interior fit-out turnkey | 1,200 to 1,800 €/m² |
A detailed, free, and personalized quote will be provided after the technical visit of our project manager.
Why transform lost attics?
Converting lost attics allows you to gain living space without encroaching on your land. It is a profitable investment, especially if you want to:
- Create one or more additional bedrooms
- Add an office or a playroom
- Improve the thermal comfort of your home
- Enhance the value of your property in Belgium
- Avoid an expensive move or outdoor extension
What rooms can you create in transformed attics?
Once the lost attics are made habitable, you can fit out:
- A master suite with a shower room and dressing area
- One or more additional bedrooms for children or guests
- A home office, quiet and bright
- A recreation room: TV area, playroom, library
- A functional and well-ventilated bathroom or shower room
Each fit-out is custom designed to adapt to the configuration of your home and your lifestyle.
Why trust Avenir Rénovations Belgium?
- Single point of contact from start to finish of the project
- Complete mastery of frame and roof transformation works
- Local, qualified, and certified teams
- Strict compliance with Belgian standards for urban planning, insulation, and safety
- Ten-year warranty on all completed works
- Commitment to quality, price transparency, and deadlines
Request your free study
Do you want to transform your lost attics into living space? Avenir Rénovations Belgium supports you at every stage of the project. Our project manager will come to your home for a free and non-binding study, and will provide you with a complete, clear, and customized quote.
Give new life to your unused attics, and gain comfort, space, and property value.
FAQ – Fit-out of lost attics
Can lost attics really be converted?
Yes, it is entirely possible to convert lost attics provided that appropriate works are carried out. This may include modifying or replacing the frame, reinforcing the floor, or even a roof elevation. A technical study is essential to determine feasibility and the best solution to implement.
What are the differences between convertible attics and lost attics?
Convertible attics have sufficient height, an appropriate roof slope (often greater than 30°), and a frame that leaves free space. Lost attics, on the other hand, are often cluttered by a W-frame, have low height under the ridge, and are not accessible. Their fit-out requires structural transformation works.
Is the fit-out of lost attics subject to a planning permit in Belgium?
Yes, in most cases. If the works involve a modification of the roof (raising, changing slope) or an external visual impact, a planning permit is required. Avenir Rénovations handles all administrative procedures with local authorities.
What is the average cost to transform non-convertible attics?
The cost varies depending on the nature of the works to be carried out. On average, you should budget between €1,200 and €1,800 including tax per square meter for a complete transformation of lost attics into living space. This price includes frame modifications, insulation, access, interior fit-outs, and finishes.
What types of rooms can be created in transformed lost attics?
Once the transformation works are completed, you can fit out a master suite, one or more bedrooms, an office, a playroom, or even a bathroom. The space obtained is customizable according to your needs, with insulation and finishes of quality equivalent to the rest of the home.
How long do the works to fit out lost attics take?
The duration of the works depends on their complexity. Generally, you should expect between 6 and 12 weeks for a complete transformation project, including structural modifications, interior fit-outs, and finishes. A precise schedule will be provided to you as soon as the quote is validated.
