Rosemount House is the headquarter building for Lagan Construction and H&J Martin. The existing building was redeveloped in 2011 with a 7,000ft2 extension. A planning application (Z/2014/1301/F) approved in May 2015 permitted an extension (not yet constructed) of 12,454ft2.

A further planning application submitted in June 2015 (LA04/2015/0689/F) proposes further extension (47,836ft2), partial demolition, re-cladding of the existing building and associated car parking and landscaping. The application was approved in September 2016.