Renovating a house: stages, budget and choosing contractors

1. Assess the house before renovating

Before choosing materials or comparing quotes, have the issues that could affect the project examined: the roof and roof structure, cracks, damp, electrical installations, plumbing and ventilation. If damp is present, identify its cause before installing linings or finishes.

Identify the building’s constraints

Creating an opening in a load-bearing wall or working on the foundations requires an appropriate assessment by qualified professionals. Check which surveys are needed before work begins, particularly the asbestos risk depending on the building’s age and the proposed work.

Develop a coherent energy improvement programme

An energy audit helps compare insulation, ventilation and heating options. It is required, in particular, under the MaPrimeRénov’ scheme for a major energy renovation. For other projects, its usefulness and the surveys required depend on the condition of the house.

2. Prepare the work and choose the right contractors

List your priorities: improving comfort, changing the layout, reducing energy use or adapting the home to your needs. Define what is essential, what can wait and your overall budget before requesting quotes.

Check the procedures before work starts

Changes to a façade or roof, an extension or a change of use may require planning permission. Consult the local council and the rules applying to your plot, particularly in protected areas. Allow time in the programme for surveys and any required permissions.

Compare quotes covering the same scope

Compare services, quantities, materials, timescales, exclusions and payment terms. Ask for insurance certificates covering the activities involved. For subsidised energy work, check the required RGE qualification and the categories of work covered.

A building work brokerage service helps you find contractors and understand their quotes. If you also want to appoint someone to coordinate and monitor the work, a construction project management service must be defined under a separate contract.

3. Address structural work and protect the house

Where justified by the assessment, work begins with stripping out and structural interventions. Demolition, masonry repairs and new openings must be prepared with the necessary protection and engineering assessments.

The roof, façades, windows and doors must protect against water ingress. Coordinate window replacement with insulation and ventilation to avoid rework and preserve air quality.

There is no universal sequence of work: it depends on the techniques selected, the contractors, supply lead times and whether occupants remain in the house.

4. Coordinate insulation, services, heating and ventilation

Once the underlying surfaces and building envelope are ready, organise services, insulation and partitions. Contractors must coordinate ducts, pipes and equipment before closing up the linings.

Choose insulation to suit the house

Roof, walls, floors or windows: priorities follow the assessment and energy improvement plan. Internal or external insulation depends on the building, available space, façade constraints and budget.

Size the heating system and provide suitable ventilation

Choose heating based on the needs after renovation, existing heat emitters and installation options. A heat pump does not make balanced mechanical ventilation with heat recovery compulsory. Ventilation must be designed to renew indoor air; an extract-only or balanced system may be chosen according to the project and its constraints.

5. Complete the finishes and hand over the work

After services and partitions come plasterwork, painting, floor and wall finishes, and kitchen or bathroom fittings. The programme must allow for drying times and protection of completed work.

Before accepting the work, check with the contractors what has been completed, whether equipment works correctly and any items requiring attention. Record outstanding items in the handover report and retain quotes, invoices, insurance certificates and instructions.

What renovation budget should you allow per square metre?

The cost of renovating a house depends on its initial condition, floor area, site access, specification and finish. A cost per square metre provides an initial budget guide; it does not replace detailed quotes.

These figures are broad indications, not price commitments. They are neither a Comabat price schedule nor the estimator’s rates. The scope, VAT, fees, surveys and additional work must be specified in each cost assessment.

Allow a contingency appropriate to the building’s condition and the investigations carried out. Separate the cost of work, professional fees, surveys and any temporary accommodation.

To prepare for your first discussion, you can use the building work estimator. Its indicative budget must be refined for your project and the contractors’ quotes.

What support is available for energy renovation in 2026?

Subject to conditions, MaPrimeRénov’ for major renovation funds an energy improvement programme achieving a gain of at least two energy rating classes. An audit and support from Mon Accompagnateur Rénov’ form part of the process. Check eligible work and required RGE qualifications before committing.

Amounts depend in particular on income, the property and the programme of work. Contact a France Rénov’ adviser to check current procedures and eligibility. Comabat’s services alone do not constitute Mon Accompagnateur Rénov’ accreditation.

Subject to conditions and bank approval, the interest-free eco-loan may finance the remaining cost of energy work supported by MaPrimeRénov’. It is a repayable loan, not a grant or automatically approved financing.