Restoring a polychrome brick chimney stack in Versailles: preserving material and design
Updated: 5 days ago
In brief: a polychrome brick chimney stack is restored by preserving its original material and design. Start with a diagnosis, redo the joints so they follow the brick using a compatible lime mortar, repair or reuse bricks rather than replacing them, clean without abrasion, and rework the flashings and zinc work. A sample panel approved before the works begin prevents most mistakes.
Updated on 25 October 2026.
Brick is a material we barely notice, until the day its joints crumble, water seeps under the roof covering or a crack weakens a chimney stack. On the rooftops of Versailles, these polychrome brick structures are among the details that give the urban landscape its character.
Restoring them is not just a matter of filling joints or replacing damaged pieces. It means understanding the masonry, identifying the causes of damage, and balancing the conservation of original material, protection from the weather and respect for the architectural appearance. The rue Mansart project illustrates this approach.
Polychrome brick chimney stacks, rue Mansart in Versailles
During a façade restoration and roof renovation on rue Mansart, the chimney stacks showed late 19th-century brickwork combining red bricks, flamed yellow bricks and glazed bricks, a language also found in the brick-effect stucco of Versailles.
At that time, a chimney stack was not merely a flue rising above the roof: its crown extends the design of the façade right up to the roofline. The aim was therefore not to rebuild, but to preserve this composition: clean without damaging, redo the joints, repair bricks when their condition allows, and replace only those that can no longer be kept. This is the principle of heritage restoration: keep the original material whenever its condition and function allow.
Start with a diagnosis
Before choosing a mortar or a cleaning method, you must understand why the masonry is deteriorating. A close inspection from the scaffolding makes it possible to tell superficial damage from deeper alterations. The survey covers:
Joints: loss of cohesion, cracking, depth of voids.
Bricks: cracks, spalling, surface flaking, detached glaze.
Moisture: stains, salts, moss or leaks, interpreted according to their location.
Stability: through-cracks, deformation, loose bricks.
Crown and roof junctions: chimney pots, flashings, chases, zinc work.
Accompanied by photographs, this survey prioritises the interventions. Above all, it avoids replacing old bricks that are still sound simply because they show the marks of time.
The joint profile: a technical question as much as an aesthetic one
The joint binds the bricks, protects the masonry from water ingress and contributes to the expression of the wall face. Its profile, width and colour are therefore chosen according to the original features still legible, the exposure and the nature of the bricks.
A joint that follows the brick
On rue Mansart, the joint was made flush, to follow the design of the bricks without creating a recess or hiding their edges. This profile limits standing water and keeps the brickwork clearly legible. A historic joint still in good condition remains, however, the best clue for deciding the finish to restore.
Conversely, a deeply raked joint artificially accentuates relief, breaks the visual balance of a polychrome wall face and can encourage water retention, especially next to glazed bricks, whose surface is fragile.
Joint thickness and colour
On rue Mansart, joint thickness was kept between 10 and 12 mm, and the joints between the yellow bricks were slightly lightened, to respect the contrast intended by the original builders. The mortar colour is judged on a sample, once dry, both up close and from the street. The goal is not to make the new pointing invisible, but to restore overall coherence without erasing the historic character of the wall face.
Mortar: compatibility before recipe
The mortar must be compatible with the existing bricks, in its mechanical properties as well as its behaviour with water. Lime is the traditional solution, but the word "lime" is not enough: binder, proportions, sand, porosity and exposure must be studied together. A mortar that is too hard transfers stresses to the brick; a poorly applied one degrades quickly.
Cement should therefore not be used by default: heritage restoration guidelines consider that pure cement or lime-cement joints rarely meet heritage requirements. The composition is defined from the diagnosis and preliminary tests, then set out in the special technical specifications (CCTP). This logic of compatibility applies to all historic materials, as with the plaster façades of Versailles.
Repair rather than replace
Spot repairs: a lightly damaged brick is kept, provided the repair does not mask a deeper problem.
Replacement and reuse: a broken brick or one damaged at its core is carefully removed, then replaced with a reclaimed brick matched in size, texture and colour.
Glazed bricks: retouched and patinated rather than replaced.
Chimney pots: damaged pots were replaced with new glazed ones, grouped by type on each stack to preserve overall harmony.
Clean without damaging
Cleaning removes the dirt that hides the legibility of the masonry, without trying to recreate the look of new brick. Gentle brushing or controlled water washing is often enough, tested first on a small area. Abrasive methods must be ruled out: they wear down edges, damage the fired surface and can destroy the glaze. Moss and deposits should also prompt a search for their cause (a defect in the crown, the junctions or water drainage), otherwise the problem returns.
Watertight junctions: flashings and zinc work
A chimney stack ages first at its base: perfectly restored masonry deteriorates again if water gets in at the flashings. On rue Mansart, the flashings and chases were redone, and the method statement was presented to the project management team before execution. This work requires close coordination between the mason and the roofer, and on-site checks, because slopes and irregularities in the masonry are not always readable on a drawing.
The dialogue between architect and craftsmen
The CCTP sets the objectives and materials, but the result depends on the craftsman’s hand. That is why a sample panel is so valuable: it validates the look of the wall face, the width and profile of the joints and the balance of colours before the work continues, up close from the scaffolding and then from a distance in the street. This regular supervision, which we also describe in our article on financial tracking of the construction site, prevents rework.
Mistakes to avoid
Repointing without a diagnosis: redoing every joint on principle removes parts that are still sound.
Using an unsuitable mortar: too rigid or different from the substrate, it speeds up deterioration.
Cleaning too aggressively: abrasion damages the brick and its glaze.
Raking out joints carelessly: it chips the bricks and widens the joints.
Replacing every brick "to be safe": replacement is justified by the condition of the brick, not by a wish for a uniform wall face.
Neglecting roof junctions: the repair will not last if leaks persist.
Applying a water repellent without study: it alters the moisture exchange of the masonry.
Frequently asked questions
Can a damaged brick be replaced without rebuilding the whole chimney stack?
Yes, when the damage is localised and the structure remains stable: the damaged brick is removed individually and replaced with a compatible one. If there are through-cracks or movement, a more thorough assessment is needed first.
Should a brick chimney stack be waterproofed?
Not necessarily. First identify how water is getting in. A water repellent replaces neither suitable repointing nor the repair of a faulty flashing.
How can I tell if a chimney stack is dangerous?
Loose bricks, through-cracks, movement or deformation are warning signs. If in doubt, have the stack examined quickly by a professional, especially if pieces could fall onto the public highway.
Is authorisation required to restore a chimney stack in Versailles?
It depends on the works and on the building’s heritage status. In Versailles, depending on the location, exterior works may require the approval of the Architecte des Bâtiments de France (article L632-2 of the French Heritage Code for remarkable heritage sites). Check the applicable procedure with the planning department before any works, and see our article on historic colours in Versailles.
Restoring the material, preserving the Versailles landscape
On rue Mansart, the approach is to examine before intervening, to keep what can be kept and to adapt repairs to the masonry. It is in this balance between diagnosis, craftsmanship and architectural standards that a lasting restoration is built.
On this site: the rue Mansart project
Antoine de Gironde
Architect DESA — Registered with the Ordre des Architectes no. 084305
Atelier d’Architecture Antoine de Gironde
10 rue de Fontenay, 78000 Versailles
Further reading
Sources
French Heritage Code (Code du patrimoine), article L632-2 (approval of the Architecte des Bâtiments de France in remarkable heritage sites).
Service public de Wallonie, Département du patrimoine, FARCC 03.0113.04.01 "Maçonneries : déjointoiement et préparation du support", a good-practice reference for heritage restoration.
