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About Group a

Group a is a Belgian family-owned company, founded in 1977 by Eugène Alen. We commercialise and offer a large range of quality windows and doors in PVC, aluminium and wood via a franchising network for our two brands, Belisol and KwadrO. Group a provides a complete concept based on market needs to service and delight the private customer.

Belisol serves the Belgian, Dutch and French markets via a franchising system. Belisol windows and doors has grown into the largest doors and windows provider in Belgium and the Netherlands. In France, Belisol is also a byword for professional advice tailored precisely to your wishes, lifestyle and home.

KwadrO serves the Flemish part of Belgium via a franchising system. KwadrO was created to cover the remaining market for windows and doors, both in terms of geographic spread and market segmentation. KwadrO offers different products, appeals to another target group and presents a different image.

Both group a brands stand for sustainability, reliability and clarity. You will always receive expertise, quality and perfect service.


Belisol founded by Eugène Alen


First Belisol showroom opens in Brussels


Start of distribution via franchising model


First Belisol showroom opens in the Netherlands


KwadrO is founded


First Belisol showroom opens in France


Group a sells a 50% stake to its competitor Atrya to conquer the French market


Family Alen regains full control after buying back the 50% stake of Atrya


40 years Belisol


Celebration 15 years of KwadrO


Belisol and KwadrO are market leaders with almost 100 points of sale in Belgium, the Netherlands and France


Second generation takes over the reins at group a