The album is a set of improvised compositions consisting of simple piano, synth, and guitar loops surrounded by tape hiss and field recordings.

[6] The album is a set of improvised, slow-tempo minimal ambient electronic compositions that were written and recorded in more than ten years using only a microphone and loop pedal.

[6] Compared by multiple reviewers to the works of William Basinski,[4][7][5] Gas,[4][8] and the more ambient records of Aphex Twin[9] and Brian Eno,[8] each song involves short piano, synthesizer, and guitar loops[10][7] being transformed into "ghostly textures," described Time Out NY.

"[9] Phantom Brickworks has a very spacious structure that uses lots of reverberation, delay, and elements of long sustain in the composition:[2][5][11] XLR8R analyzed it has a "widescreen vibe," where the tracks have "patient, sometimes nearly imperceptible cycles of accretion and subsidence" and, as a result, "feel as much like landscapes as they do music.

[4][10] As Clash magazine noted, "the material on Phantom Brickworks writes its own rules [of ambient music] as it progresses, with Bibio uncovering fresh techniques simply through the act of performance.

"[8] The Music opined, "It'd be tempting to write this off as a potboiler in between major projects, but there are subtle undercurrents of emotion that gently reel in the patient listener.