Rationel FORMAPLUS Timber/Aluminium Window Range

The design of FORMAPLUS is slim and traditional, available in a range of country-style designs with various configurations of glazing bars. The slim design also allows maximum natural light into the home.


Rationel AURA




Rationel FORMA




Made from timber, with external aluminium cladding, Rationel FORMAPLUS offers all the benefits of natural wood on the inside and easy maintenance on the outside. The range is available with security ironmongery as standard, and are suitable for Passiv Haus buildings. With high performance triple-glazing or double-glazing, FORMA windows achieve U values as low as 0.79, which is ideal for low energy buildings and Passive House construction.


Security Hardware

Rationel FORMA & FORMAPLUS come with security hardware as standard to meet SBD requirements. The vast majority of timber originates from FSC-certified forests.

Secured By Design
Rationel Logo

Windows With Vision

Good, solid, quality workmanship has characterised Rationel’s windows and doors since the first products were shipped from our factory in Sdr. Felding in 1954. Based on this sound foundation, Rationel is today an international company with sales offices in Great Britain, Ireland and Denmark. Rationel manufactures energy saving windows and doors of premium quality in terms of both comfort and security. Our continuous programme of research and development ensures that the company always meets current statutory requirements as well as market requirements for design and functionality.

Rationel is part of the DOVISTA Group, which consists of ten leading door and window companies in Europe. DOVISTA A/S is owned by VKR Holding and employs approximately 13,500 people in more than 40 countries.

Opening Types

Top Guided

Top Guided windows are a simple, elegant and user-friendly design. Opening is controlled by tracks and slides. When opening the window the top of the sash slides downwards as the bottom of the sash opens outwards. Adjustable friction ironmongery allows an almost infinite choice of open positions.

Top Swing

In everyday operation the fully reversible window functions as a Top Guided window. However it is possible to turn the sash through 170 degrees to clean the glass from the inside.

Side Hung

Side Hung windows are controlled with tracks and slides. On windows over 424 mm wide, the handle controlled friction brake allows the window to be fixed in any open position.

Side Guided

Side Guided windows are controlled by tracks and slides that allow the window to be fixed in any open position. However, when opened, the hinge side of the sash moves toward the middle to create an opening that allows the glass to be cleaned from the inside.

Fixed Light

Fixed Light windows are ideal wherever maximum internal light and solar heat gain is required.

Side Swing

The side-swing window is a modern outward-opening window where the sash can be swung approximately 160° in the horizontal plane. The window is especially suited to smaller sash widths of up to 1000mm. Since the sash is able to be swung almost 180°, it becomes a simple task to clean the outside of the window from within the house.


When choosing windows and doors from Rationel, it is possible to enhance the appearance and character of your house through your choice of colour. Our standard colours suit the majority of architectural styles and traditions in the United Kingdom. We also offer a special range of colours, which you can use to highlight particular features of your home.

Standard RAL Colours

Rationel FORMA and Rationel FORMAPLUS windows and doors are available in one standard colour on both the inside and outside of the frame. It is possible to have a split colour solution on Rationel FORMAPLUS, where you are able to have a different colour on the outside to what you choose for the inside.

If you require a colour that is not listed within our Standard colour range above, we are able to offer any colour from the RAL classic range; these will be subject to additional costs and lead times.

* The colours shown cannot be reproduced exactly.

Granite Colours (Rationel FORMA+ Only)

* The colours shown cannot be reproduced exactly.

* Will be subject to additional leadtime.

Minimum/Maximum Sizes

Opening Function Minimum Width Minimum Height Maximum Width Maximum Height
Top Guided 358 mm 388 mm 1798 mm 1598 mm
Side Hung 358 mm 358 mm 948 mm 1798 mm
Side Guided 458 mm 438 mm 998 mm 1598 mm
Top Swing 558 mm 548 mm 1598 mm 1598 mm
Side Swing 478 mm 530 mm 998 mm 1599 mm
Fixed Light 250 mm 250 mm 2998 mm 2998 mm

Max width and height are subject to glass weight and spec.

Durability Tests

A series of test videos are available to view on the website.

Sectional Details

Download full set of drawings at www.rationel.co.uk

Best Performance

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