How to replace windows in a protected area: a step‑by‑step guide
- Antoine de Gironde
- May 28
- 5 min read
Window replacement is one of the most frequent works in historic housing. In protected zones, such as the surroundings of a listed monument or a Site Patrimonial Remarquable, this apparently simple task is subject to regulations that impose precise requirements on materials, profiles and finishes.
Each situation is unique. Factors such as the state of the existing windows, the nature of the masonry, the sector’s protection status, and the ABF’s particular requirements for the building mean generic advice is insufficient. A detailed diagnostic must be carried out first — it will establish whether to restore or replace, which materials may be used, and what changes to the masonry will be needed.
Why are windows subject to particularly strict regulations?
Exterior joinery is one of the elements that most strongly define the character of an old façade. Leaf proportions, mullion profiles, glazing bars, colour, material — all contribute to the architectural unity of a building and of a street. The arrival of double glazing and PVC in the 1980s profoundly degraded the appearance of many historic buildings. Heritage authorities have tightened their positions accordingly.
What authorization must be obtained?
In an SPR, replacing exterior joinery requires a prior works declaration filed at the town hall. Forms are available on service-public.fr. That declaration is processed with the opinion of the Architecte des Bâtiments de France. Allow two to three months between filing and receiving the authorisation.
What are the restrictions on materials?
PVC is almost always refused in heritage areas. Acceptable materials are wood and aluminium, under conditions. Wood remains the reference material: it is compatible with historic profiles and can be painted in the prescribed colours. Lacquered aluminium is allowed provided the profile is sufficiently slim. Colour is prescribed by the ABF or the PSMV regulations.
Can we install double glazing?
Yes, in the vast majority of cases. Enhanced-insulation glazing (VIR) provides satisfactory thermal performance without excessively altering the profiles. There are also internal secondary-glazing solutions, which are particularly interesting when the original windows are in good condition.
Should the glazing bars be retained?
In SPRs, the preservation or reproduction of glazing bars is generally required when they were part of the original design. There are two options: applied glazing bars (fixed onto the glass) and true/mullion glazing bars (integrated into the structure). The ABF sometimes specifies which type is acceptable.
Ironmongery is an integral part of the design of an historic window. Espagnolette bolts, latches, hinges and cremone bolts contribute to the authenticity of the whole as much as the profile or the colour. For restoration or replacement projects, the Studio selects specific ironmongery suited to historic windows (wrought iron, brass, cast iron), relying on specialist manufacturers who supply adaptations of original fittings consistent with the character of the building and the heritage area. To deepen knowledge of historical profiles and ironmongery, the site chassis-fenetres.info offers outstanding studies and surveys of window frames from the 15th to the 18th century.
The detail of the sashes
Choosing a window isn't limited to material and colour. The design of the opening — number of leaves, direction of opening, proportion of rails and stiles, presence or absence of a glazed lower panel — must be consistent with the building's architecture and comply with the ABF's requirements. In protected areas, certain details are mandatory: flush or rebated fixed frames, moulding profiles, and the type of exposed ironmongery.
The interface with the existing masonry
This is often where future pathologies originate. A joinery installed carelessly at the junction with old masonry causes leaks, thermal bridges and render detachments.
Contemporary joinery has frame sections that are significantly larger than the historic frames they replace. This difference usually requires reworking the rebate in the existing masonry (dressed stone, lime render, brick) to properly house the new frame without creating an unsightly step on the façade or a thermal bridge in the reveal. This adaptation must be anticipated at the design stage, costed in the technical specifications (CCTP), and carried out by a mason experienced with historic fabric. It is seldom included in joiners' quotes and is a frequent source of unforeseen additional work.
The architect's role: survey, detailing and colour research.
Before any decision, the project architect carries out a precise diagnostic: condition of existing joinery, analysis of the reveals, measured records of original profiles, and investigation of historic colours beneath successive paint layers. This colour analysis is decisive in protected areas, where the ABF may require a reference colour and where an original hue uncovered by sondage is the strongest argument to support the proposed choice.
The architect then prepares detailed joinery drawings, writes the technical specifications in the CCTP, and supervises installation on site. They ensure coherence between the window design, its interface with the masonry, and the heritage requirements.
Two projects illustrate this approach: the restoration of the joinery at Château Amikuze in the Basque Country, where the windows were reinstated in accordance with applicable prescriptions; and the replacement of the joinery at the Hôtel Rousseau in Versailles — the former residence of Jules-Antoine Rousseau, ornamentalist to King Louis XV, now used by the Banque de France — carried out in a protected sector with particular attention to 18th‑century profiles and to research into original colours.
In some cases, a joinery restoration or replacement project may receive the Fondation du Patrimoine label, which can give access to significant tax benefits. We set out this scheme in our article ‘The Fondation du Patrimoine: label and funding.’
How to prepare your prior notice (déclaration préalable) file?
A complete file includes: a location plan, photographs of the current state, a graphic document showing the project (profile, material, colour, muntin/bar pattern drawings), and a descriptive note. Our practice prepares these files in full as part of its project‑management mandate.
For projects in a protected sector, the studio produces historical studies and diagnostic notes which the Maison de l'Architecture et du Patrimoine of Versailles reviews before any formal submission. This preliminary opinion helps refine intervention choices and ensures their consistency with the PSMV prescriptions.
And in co‑ownership?
Exterior joinery is generally part of the common areas, which requires a decision at the general meeting. The architect in charge of the project prepares the brief, consults contractors, and coordinates the permits. See our condominium projects for concrete examples.
To go further
Antoine de Gironde
Architecte DESA — Registered with the Order of Architects n°084305
Atelier d'Architecture Antoine de Gironde
10 rue de Fontenay, 78000 Versailles
