Outstairs is the fifth ECM album by the ensemble of the Norwegian pianist and composer Christian Wallumrød, and one of its most open. His writing is instantly recognisable: chamber music drawn from the sonorities of Norwegian folk and church music, touched by early music and the post-Cage avant-garde, and freed by the habits of jazz. Here the members share the arranging between them, and the music becomes more flexible as new combinations of sound appear. In 2013 the album won the Spellemannprisen, the Norwegian Grammy, for contemporary music.

Wallumrød plays piano, harmonium and toy piano. The sextet also includes Eivind Lønning on trumpet, Gjermund Larsen on violin, viola and Hardanger fiddle, and Per Oddvar Johansen on drums and vibraphone. Tenor saxophone and cello are played by two newcomers to the group. Johansen has been part of the ensemble since its first album, Sofienberg Variations, and Lønning joined in 2008. The album was recorded at the Auditorio of Radiotelevisione svizzera in Lugano, in collaboration with RSI Rete Due, with Markus Heiland as engineer and Manfred Eicher as producer. All eleven pieces are by Wallumrød.

The opening Stille Rock begins as a pulse between two piano chords. Percussion, strings and stronger drumming join in turn, and sudden silences fall just where a resolution seems certain. Bunadsbangla is a slinky folk dance, while Very Slow sets the ground tempo that much of the album keeps, in a manner Tyran Grillo of ECM Reviews likened to Morton Feldman. In the title track, strings and treble keys hop and skip before turning into long sliding sounds and the whirr of a musical saw.

In The Guardian, John Fordham found the music "old, new, manic and tranquil in seamless concordance", and noted that it sounded freer and more playful than before. Nick Coleman wrote in the Independent on Sunday that the six players move in small groupings at slow pace, and that "simple motifs carry the weight of mountain ranges". In the Frankfurter Allgemeine Zeitung, Jan Brachmann named György Ligeti and György Kurtág, rather than Monk or Ornette Coleman, as the godparents of this music.

CD edition, ECM 2289, first released on 5 July 2013.