Transforming a window into a French window: advice quote and price

The luminosity contributes amply to the comfort of the dwelling. To take advantage of an interior flooded with light, we can therefore decide toincrease the glazed surface by installing a French window instead of a window. This is also necessary for direct access to the terrace or the garden from a particular room, or to create a bedroom in the garage. Please note that formalities are required when you wish to transform the openings of his house. Moreover, this modification involves more or less substantial and costly work depending on the type of construction. It is in any case an operation that is better to entrust to an experienced craftsman if you are not a DIY professional.

Window transformed into a French window: the formalities

Various formalities are necessary before transforming a window into a French window.

Request for work authorization

A application for work permit must be deposited at the town hall of the commune before starting the work which consists of enlarge an existing opening since it changes the facade. The contracting authority therefore has the obligation to complete a specific form which will be given to him by the Town Planning Department. As a general rule, the response is sent to the applicant within one month of his request. The response time is longer if the request is sent by the town hall to the Buildings of France.

The mandatory standards to be observed concern the material, shape, color and dimensions of the patio door to be installed. Depending on the location of the property to be modified, the mandatory standards must be respected within the framework of:

  • From the POS: Land Use Plan,
  • De la ZPPAUP : Zone Protection of Urban and Landscape Architectural Heritage,
  • From the PLU: Local Urbanism Plan,
  • AVAP: Area for the Enhancement of Architecture and Heritage,
  • Buildings of France.

There is therefore no question of derogating from Article R. 421-17 of the Town Planning Code.

Request for a building permit

This formality is necessary if you want to transform the window of a non-habitable part of the house into a French window so that this room becomes a bedroom or an office, for example. This is a change of destination of the building, which increases the existing living area. In this case, as stipulated in article R. 421-14 c of the Town Planning Code, it is imperative to file a Request for a building permit before starting the construction site.

What does the transformation of a window into a French window involve?

To increase the dimensions of an opening already in place, the essential work to be planned is as follows:

  • Removal of theopening or openings, depending on the model of the existing window (single or double leaf),
  • The removal of the part fixed in the wall and which is called the dormant,
  • Taking the dimensions and tracing on the wall of the French window to be installed,
  • The installation of a prop because any wall must be supported when the enlargement of an opening is about to be carried out,
  • The demolition of part of the wall according to the study previously carried out,
  • The realization and installation of a lintel to replace the old one since the dimensions are different,
  • The installation of the French window which replaces the old window,
  • Installation of finishing profiles and waterproofing,
  • The plaster fitting so that the exterior appearance is identical to what it was before the work,
  • Interior plaster fittings, but also paint or any other wall covering.
  • Enlarging the opening from below: between €500 and €1,600
  • Enlarging the opening in width: between €1,500 and €3,000*
  • Removal of the window: from 90 to 150 €
  • The price of the patio door to be installed: from 250 to 1,000 €
  • The installation of the French window: between 150 and 350 €
  • Finishing work inside and outside the house: from 150 to 600 €

We understand that this type ofenlargement of an opening requires serious building knowledge as well as extensive experience in various fields (masonry, painting, etc.). This is the condition sine qua non so that the result is perfect.

Create a French window instead of a window: prices

Several things must be taken into account when budgeting for the work of transforming a window into a French window, namely:

* The prices depend on the material that constitutes the wall to be broken (wood, concrete, cinder block, brick, cut stone).

The erection of scaffolding is to be expected when the work takes place at a level other than the ground floor. The price varies from one professional to another, and also depends on the type of scaffolding to be installed (stepped, suspended, mobile, fixed, etc.). Finally, if the craftsman does not have his own scaffolding, he will be forced to rent one, which can further increase the score.

Finally, we must also think about the budget that is necessary if we decide to add to the new patio door:

  • And big curse standard or made-to-measure: prices vary between €500 and €3,000,
  • And shutter : as an indication, it is necessary to count between 300 and 1,200 € depending on the type of shutter desired (swinging, folding, sliding, manual or motorized rolling).

Aid is likely to be granted under conditions, but it is better to make sure before starting the work, because the agreements evolve over time. Some aid is likely to disappear depending on the decisions taken in high places and new ones are put in place…

By completing a form, it is possible to quickly receive free and non-binding quotes. This makes it possible to precisely estimate the cost of the work and to compare the various proposals of local companies specializing in the removal and installation of windows and the enlargement of an opening. Some professionals apply decreasing rates when the work concerns the replacement of several windows.

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