Eldest son of John Clarke Sims, Henry A. Sims was born in Philadelphia and trained as a civil engineer. In 1851 he moved to Canada to study his profession and engaged in the construction of a number of railroads while in the employ of the Bytown and Prescott Railway. Around 1856 he changed professions, deciding to pursue architecture instead of engineeering. In Ottawa, Canada, Sims launched a successful architectural office in 1858. He also became a Canadian citizen, but in 1866 he returned to Philadelphia and subsequently is cited in the Philadelphia city directory of 1868 with an office at 6th and Walnut streets. By 1872 he had been joined in his office at 426 Walnut Street by young brother James P. Sims
, and the two continued a successful practice at that address until the elder Sims's death in 1875.
Many of Sims's buildings in both Ottawa and the Philadelphia area display his interest in the Gothic Revival, most appropriate for the churches which he and his brother designed, such as St. Johns Episcopal Church in Prescott, Canada, but also for the many country and city residences which the brothers produced.
Sims was one of the organizers of the Philadelphia Chapter of the AIA, and he served on the Admissions Committee beginning in 1870 and was active on its education committee.
Following Sims's death, friends in Canada remembered him: "A memorial window to the memory of the lae Henry A. Sims, architect, of Philadelphia, has been erected in the Episcopal Church of St. John, Prescott, Canada. The window is of two lights; the first division bears the Inscription: 'Henry Augustus Sims. Born Dec. 22, 1832; died July 10, 1875;' and the second: 'John Clarke Sims. Born May 4, 1866; died March 5, 1874.' The window was designed by the late Mr. Sims himself, when his child, John Clarke Sims, died. Before the work had been commenced Mr. Sims followed his son to the grave; and the window has now been put in by Mr. Spence himself as a token of his friendship for the deceased. There is something peculiarly appropriate in the placing of this window in St. John's Church, Prescott, -- a church which was designed and erected by Mr. Sims, and which was, indeed, his earliest work." (American Architect and Building News 30 June 1877, p.212)