Sir John Soane’s House Museum in London is in the midst of a much-needed expansion, renovation, and restoration.

The legendary Sir John Soane’s Museum, at Number 13 Lincoln’s Inn Fields in London, has been undergoing an intensive expansion and restoration program that is expected to be completed in 2013. With the help of public and private funds, already one significant piece has been has been finished: In early 2008, the museum opened a restored and remodeled structure at Number 14, which Soane designed but never used — as he did Number 12, his first residence, and the more lavish Number 13. In the latter, he fully developed his idiosyncratic Romantic-Classical living and working quarters and a museum, whose encrusted, skylighted galleries would run through the backyards of the three buildings. (Disclosure: This writer serves on the voluntary board of the New York–based Sir John Soane’s Museum Foundation.)

Between 1792 and 1826 Soane purchased three properties on Lincoln’s Inn Fields, demolishing their structures and rebuilding town houses. Although the facades of Numbers 12, 13, and 14 form a triptych, with Number 13 as the prominent centerpiece, Soane bought Number 14 in 1823 to make over for rental income. It was ultimately sold in 1873. Since Soane did not intend to live in it, the interior was neither as lavish nor as intricate as Numbers 12 and 13; indeed, he never furnished it. But his plaster decoration and fitted joinery remained intact over the years. In 1996, with the help of lottery funds, the museum acquired Number 14 . Now it is home to a much-needed education center (basement), seminar room (ground level), research library (first floor), and the Robert Adam Study Centre (second level), with offices on the two floors above.

At Number 14, Julian Harrap Architects replaced the slate and lead roof, inserted steel beams in the floors, tore down partitions and false ceilings, and installed new plumbing and wiring. Harrap also reorganized the ground floor according to Soane’s original plan and reinstated a large arched recess in one wall of the front room. The team restored the original Baltic pine floors, windows, and doors in the house, along with the mahogany stair rail. Over the central stair, it replaced the post-Soane skylight with a new one of Soanian influence.

The highlight, however, is the now restored lath-and-plaster dropped starfish ceiling in the research library. Colors throughout approximate ones favored by Soane, including the Pompeiian red walls in the front room. With regard to the furnishings, the architects chose to have the library and study center look domestic as well as toned-down, says project architect Lyall Thow.

Since the arrival in 2005 of museum director Tim Knox, a battery of renovations and remodelings have advanced into the other two buildings. A special exhibitions gallery designed by Caruso St. John Architects is to open in 2012 on the first floor of Number 12. It replaces the smaller gallery on the ground floor of this house that Eva Jiricna executed in 1995, which is giving way to a reception area, coatroom, and shop.

The most significant undertaking in this series of significant adjustments is the reconstitution of Soane’s own bedroom and the morning room for Mrs. Soane on the second floor of Number 13. In addition, the model room is being brought back to this floor, where it existed in Soane’s time. These changes have allowed (and encouraged) the relocation of many of the museum’s offices to the top floors of Number 14. The diminutive aeries are still full of character — and architecture — adding to this incredible ensemble, although they are not on public view.