Customized windows and doors: what to know about bespoke frames and designs

Customized windows and doors: meaning and types

According to the Italian Civil Code, windows are generally divided into two main categories: those that allow the passage of light and air (known as non-opening, transom or fixed windows) and those that can be opened, designed to offer a view or ventilation.

Within these categories, we find bespoke windows: special solutions that deviate from the traditional, rectangular windows to adapt to irregular wall openings or distinctive architectural styles. In some cases they are a technical necessity, such as in historic buildings or renovations where walls are no longer perfectly straight; in others they are a deliberate design choice, meant to enhance the building’s facade and style.

A custom window can feature an oblique, curved, trapezoidal or arched frame shape, but it doesn’t always need an unusual design. Sometimes it’s simply a modular combination, like a standard window paired with a shaped transom above.

In all cases, a custom window frame design requires accurate measurements and dedicated planning to ensure proper insulation and the aesthetic balance of the home.

Custom window models, opening systems and materials

Custom windows and doors stand out for their distinctive and unique design, making them suitable both for architectural restorations and for modern construction projects.

The most common bespoke window models include:

• Arched windows (or semi-circular windows): ideal for historic buildings or classic settings, often available in full, pointed or lowered arch styles;
• Trapezoidal windows: perfect for attics or sloped walls, often found in lofts;
• Triangular or oblique windows: great for filling unconventional spaces;
• Oval or round windows: inspired by naval and industrial architecture.

Each window design can (or can’t) be paired with different opening systems, depending on geometry, intended use and performance requirements:

• Fixed windows: ideal for complex shapes, offering excellent thermoacoustic insulation;
• Side-hinged windows: easy to handle especially for rectangular or trapezoidal frames;
• Wasistas windows: open inward from the top, perfect for small spaces and ventilation;
• Pivot windows: rotate along a vertical or horizontal axis, suitable for large sashes;
• Sliding windows (lift or tilt-slide): applicable on straight sections of shaped frames.

As for materials, custom windows made with uPVC or uPVC/aluminum frames represent an excellent solution in terms of versatility, insulation and personalized geometry. These materials can be shaped into even the most complex frame designs, ensuring maximum durability and minimal maintenance. These characteristics make customized uPVC windows a preferred choice in both residential, commercial and public buildings.i grande rilievo. 

Regulations, permits and restrictions for custom windows

The installation of custom windows and doors can fall into two main categories, each with different regulatory permits and implications depending on the country.

• New opening or window expansion: creating a new wall opening or significantly altering an existing one (for example, converting a standard window into a French door) may be considered a structural change that affects the exterior appearance of the building. In many countries, this type of frame renovation work typically requires a formal planning permission or the approval from local authorities.
• Replacing an existing window: if the new window frame design matches the existing opening in size and shape, the project is often classified as routine maintenance or minor work. In such cases permits may not be required, although local regulations may still impose limits (especially in heritage zones or protected buildings).

Each country has its own construction codes and permitting systems for custom design windows and doors. For instance, in Italy, different types of authorizations may be needed depending on the intervention, such as simplified notifications, full building permits or no permits at all in the case of minor upgrades for windows and doors.

Before starting a renovation or building project, especially involving custom frame designs or structural changes, it’s always recommended to consult a licensed professional (architect or engineer) or an expert company familiar with the local regulations.

The importance of proper installation in custom windows

When it comes to customized doors and windows, installation is not just a technical step: it’s the core of the entire project. Unlike standard windows, which are fitted into perfectly square wall openings, irregular windows or bespoke designs require highly accurate measurements, tailored solutions and professional expertise. Even a minor installation error can compromise the performance and durability of a window frame.

A professional installation typically follows the “three functional layers” principle:

• Exterior layer: protects against wind and rain while allowing moisture to escape;
• Middle layer: ensures thermal and acoustic insulation using appropriate materials;
• Interior layer: seals the room from moisture and condensation, preserving comfort.

Another key element is the use of a subframe, often preferred over direct installation into masonry in certain building systems. The subframe acts as a structural guide, enhances long-term stability and helps protect sealing joints from wear and damage.

For all these reasons, installing a customized window is not an easy task. Only a qualified professional can accurately interpret on-site measurements, choose the right materials and deliver a result that meets both performance and aesthetic expectations.

DQG: the best choice for unique window and door frames

Designing and installing bespoke doors and windows with non-standard geometries requires technical expertise, precision craftsmanship and deep industry knowledge. DQG meets these demands with a fully customized window and door frame production, capable of adapting to even the most ambitious architectural requirements.

Arched windows, triangular, squared or other unique window designs are not exceptions for DQG: they are a well-established specialty. With over 50 years of experience and a Made in Italy production, we manufacture custom windows and doors, fixed frames and special transoms, tailored for both private homes and large-scale building projects.

All DQG products are made using next-generation uPVC or uPVC/aluminium profiles, compatible with high-performance glazing and equipped with advanced opening systems even on non-standard shapes, as our most recent installations show.

As a testament to our commitment to quality DQG is a PosaClima-certified company, adhering to the leading Italian standard for high-performance doors and windows installation. This certification ensures that we are the ideal partner to transform any technical challenge into an opportunity for value and design excellence.