The 52-year-old was carrying out maintenance work inside a house in Triq ix-Xatt when a wall collapsed at about 12.15pm, according to a police report.
The rubble buried the man, Spiru Abela, and although the Civil Protection Department raced to the scene to free him from the debris, he was certified dead on site.
Duty magistrate Giovanni Grixti appointed a number of experts to assist in an on-site inquiry. Zabbar District Police are investigating.