The Cadishead-based contractor, founded in 1975 by the late Patrick Flynn, has transferred ownership to an employee ownership trust.
The business, which has 24 staff, works nationwide on projects spanning utilities, energy, flood defence, education, and industrial buildings.
Managing director Peter Flynn, who continues to lead the firm, said the move was about protecting both clients and staff.
He said: “We’ve been working with most of our customers year on year, some of them for more than 40 years.
“In exploring options for the future, our ambition was to ensure continuity and protect the interests of our clients and our people. Moving to employee ownership was the best way to achieve this.”
Lowbury’s shareholders were advised on the EOT sale by MHA corporate finance and tax teams.