Rationel
Forma & FormaPlus

Rationel Windows is a manufacturer with more than 60 years’ experience. Rationel employs 1,050 people in Denmark, England, Ireland and Poland, manufacturing premium-quality, durable and stylish windows and doors.

We are a FENSA-registered Rationel distributor and approved installer. When we supply and install, we offer this as a single contract: the product itself, transportation, survey and installation are all included within your order.

Rationel Forma and FormaPlus Options

Both Forma and FormaPlus have a wide variety of opening designs, glazing options and configurations. Along with the typical styles, Rationel FORMA and FORMAPLUS can be manufactured in bespoke shapes to correspond to an assortment of openings. Featuring fully adjustable and secure ironmongery (Secure by Design part Q compliant hardware), two gaskets and the option of trickle vents, FORMA and FORMAPLUS are carefully engineered with the customer in mind. Furthermore, all Rationel products prioritise energy efficiency. The slim design naturally takes advantage of the solar heat from daylight, and their exceptional insulating qualities reduce CO2 emissions significantly.

Due to their energy efficient characteristics, both Rationel FORMA and FORMAPLUS are suitable for Passiv Haus buildings.

Thanks to constantly enhancing efficiency and optimising their products, Rationel windows are designed to withstand all weather types, attempted break-ins, and the constant wear and tear of opening and closing windows year after year.

Marine Suitability

Rationel aluminium profiles are coated with a minimum of 60 microns thickness and are pre-anodized so can be called marine grade. The windows and doors will require regular maintenance as per the OE manual shown in the downloads tab of this page.

Efficiency, Solidity, Dependability

The Rationel product development is primarily based on the Danish market and climate which is predominantly coastal – similar to northern Scotland – so the products are suitable for coastal locations. We treat the aluminium for filiform corrosion prior to powder coating, and the products are also salt-spray tested at R&D stage. Furthermore, salt-spray batch testing is completed on all metal components, from cladding to hinges.

“We basically offer a complete service. For over 60 years, our company has been based on excellent craftsmanship. This is still the case. At Rationel we take pride in delivering high quality,” Rationel CEO, Thomas Tvedergaard Larsen.

We have and extensive range of doors available in Rationel Forma and FormaPlus, the images above show some of the general configuration options available. For more information about the opening types and how each can best be used see our Bespoke Doors page.

For more in-depth options on the look of single or double doors our Choosing a Panelled Door and Choosing a Glazed Frame-Door pages will go into more detail.