Reginald Bedford Hammond was born on 10 September 1894, at Te Kopuru, North Auckland, the son of Lucy Gertrude Masefield and her husband, Horace Hammond, a civil engineer. He trained and worked as an architect and surveyor in his father's firm in Dargaville, and studied architecture part time at Auckland University College. Around 1921 Hammond travelled to Britain to study town planning at University College, London; in October 1923 he became a member of the Town Planning Institute, London.
Probably New Zealand's first professionally trained town planner, on his return Reginald Hammond worked as an architect in Auckland and Dargaville, and became an associate of the New Zealand Institute of Architects. He rose to national prominence in 1925 when he won first prize in the Department of Lands and Survey's design competition for the proposed Orakei Garden Suburb; this later became the basis of the first Labour government's state-housing programme in Auckland. Later that year he won a similar competition for the Lower Hutt eastern township. Around this time Hammond's attention turned from urban design to town planning: he helped to draft New Zealand's first Town-planning Act in 1926, and in September that year became the first director of town planning. In this role he was a vigorous advocate of town planning and travelled extensively to lecture on the subject. It was also a significant year in his personal life: on 14 October 1926 Hammond married Cecily Sutherland Chambers at St Mark's Church, Remuera; they were to have four daughters and one son.
Hammond was only briefly director of town planning, resigning in 1927 to return to private practice, where he felt he could more effectively assist local authorities to produce town plans. He retained the position temporarily until J. W. Mawson was appointed in 1928, then resumed private practice as an architect and town planner in Wellington, then Auckland.
In 1935 Hammond became part of an influential committee established by Gordon Coates to examine the growing housing problem. The committee's report presaged the large-scale state-housing programme of the Labour government, elected later that year. Hammond returned to the public service in November 1936, when he was appointed town planner and housing consultant to the new Housing Construction Branch of the State Advances Corporation of New Zealand. Alongside the director of the branch, Arthur Tyndall, and chief architect, F. Gordon Wilson, he was a key figure in the implementation of Labour's scheme. By March 1940 the Department of Housing Construction (as the branch had now become) had completed 6,459 houses. In 1943 it became part of the Public Works Department.
Reginald Hammond was a strong advocate of the concepts promoted by the garden city movement, which sought to integrate good housing design with effective land-use planning to create a healthy and pleasant living environment. One of his major achievements in the late 1930s was the Savage Crescent development in Palmerston North, which produced an attractive and successful community. Although primarily involved in housing, Hammond maintained his professional links with town planners, through the Town Planning Institute of New Zealand and its successor, the New Zealand Branch of the Town Planning Institute, London, of which he became chairman in 1947. He was also involved in a number of government committees relating to town planning, including one which in 1941 produced the Standard Code of Clauses for Town Planning Schemes.
After the Second World War Hammond held a number of senior public service positions, becoming assistant director of housing construction in 1946 and director in 1949. In these positions he sought to reassert the importance of housing, focusing on the clearance of inner-city slums, the development of low-cost housing alternatives, and town planning issues. He was, however, slow to accept that these required community and social planning as well as land-use planning, reflecting his continued adherence to the environmental determinism of the garden city ideas.
In 1958 Hammond retired to Waikanae, where he was a keen gardener and bowler. His wife, Cecily, died in 1959, and on 1 July 1961, at Wadestown, Wellington, he married Hazel Reid (née Thompson), a jewellery assistant. She died in 1969, and Reginald Hammond died in Porirua Hospital on 1 October 1970, survived by the children of his first marriage.