Was born at Labori et Picardi, Suider Paarl and educated at the Boys' High School, Paarl, from where he went to study at Rhodes University, Grahamstown for a short time before transferring to the University of Cape Town. His principle achievement during these years was as participant in the rugby first team which seems to have occupied most of his time as a student of land surveying. More by chance than desire, he went to work as a draughtsman in his brother Wynand's office 1919-1920. This stimulated an interest in architecture and he went to London in 1920 to study at the Architectural Association School, graduating in 1925. As a student he visited a number of European countries and gained office experience with Sir John Burnet & Partners, where he worked on Sydney Harbour Bridge among other jobs; and with Easton & Robertson, April-July 1925. He played in the AA first team rugby. In 1925 he returned to South Africa and worked for his brother, Wynand LOUW. His work at the time included a house, Picardi, for his brother Louis, and the 'stomp toring' (spire) of Dutch Reformed Church at Worcester.
In about 1925 he opened and ran an office for LOUW & MOERDYK in Bloemfontein. Soon after his arrival in Bloemfontein, the Gereformeerde Church asked LOUW & MOERDYK to design a new church near the Ramblers Club; this was executed according to HJ's design. About the time HJ entered the competition for the Main Building at Potchefstroom University (c1930 -), the LOUW & MOERDYK partnership was dissolved and HJ was admitted into partnership with his brother WH LOUW (cf LOUW & LOUW).
The Bloemfontein office was thereafter run by another brother George LOUW. HJ continued in partnership as LOUW & LOUW until Wynand LOUW's death in 1967 when the firm became LOUW, GELDENHUYS, JOUBERT & LIGHTON. LOUW retired in 1975.
He married Helena van Niekerk at Klipkoppie, Clocolan. In 1942 his address was listed as 14 Derwent Road, Tamboerskloof, Cape Town.
ARIBA 1925; ISAA 1927.
(ARIBA nom papers (1925); CPIA MS HJ Louw; ISAA mem list; Kesting 1978; SAAR Feb 1934:58; Die Afrikaner Persone Register 1942, Voortrekker Pers, Johannesburg, 1942:145)
All truncated references not fully cited in 'References' are those of Joanna Walker's original text and cited in full in the 'Bibliography' entry of the Lexicon.