Schlegel was an architect schooled and driven by function. He saw possibilities in the aesthetics of modernist design and materials; becoming one of the first architects in Denmark to experiment with concrete in architecture.
Early works show inspiration from the French architect Auguste Perret - le Corbusier's one-time employer - a world leader in reinforced concrete construction. This is reflected in one of Schlegel's most important works, Mariebjerg Kapel & Krematorium.
He completed an apprenticeship as a mason in 1915 and studied architecture at the Royal Danish Academy of Fine Arts, graduating in 1923. Schlegel then established his own architectural practise in 1934 and designed several furniture ranges in the 1930's; some were pre-fabricated and produced by Frits Hansen. They had a strong functionalist appearance, with nods to the Bauhaus. He also turned his hand to lighting