Mr McLauchlan's company Beach Road Ltd has bought the three-storey Moray Pl building in which another of his companies, Crest Commercial Cleaning, would be an anchor tennant.
He said there would be 1350m square of lettable space in the building, which had a total floor area of 1760m square.
Eight commercial tenants were already leasing space, along with a three-bedroomed apartment.
Mr McLauchlan said he had outgrown his premises and needed extra space and said buying the former RSA building was an opportunity that seldom presented itself.
The building would be retrofitted along ecological building and design lines and in keeping with the 90-year-old structure's historic status.
That meant using natural light, natural heating and the careful use of water, sympathetic design and materials, something he said he had successfully done with the development of another historic building in Moray Pl.
Mr McLauchlan said he was confident the central city location would attract tenants while the varying size of space available would also appeal to businesses of different sizes.
"People will pay for quality, centrally located buildings," he said.
Work would start on developing office space for Crest in April and further redevelopment as tenants required.
The building was opened as RSA club rooms in 1920 and was upgraded after a fire in 1962.
In 1996, it was bought by Bill and Margaret Van der Vis, who live in the three-bedroomed apartment.
