Lower middle market private equity firm Silver Oak Services Partners has invested in Commercial Cleaning Systems LLC for an undisclosed amount. The target’s management team is also partnering with the PE firm on the deal.

Commercial Cleaning, based in Denver and founded in 1988, provides window cleaning, porter services and flood restoration. The company works with office buildings, health care facilities, and residential communities.

“We believe the company is a great platform from which to grow in janitorial services due to its strong reputation in each market, service-oriented culture and experienced management team,” says Silver Oak managing partner Greg Barr. The firm typically invests in companies that have up to $20 million in Ebitda.

Silver Oak says the maintenance services sector provides attractive investment opportunities because it is fragmented, has recurring revenue and it is less cyclical compared to other industries. For example, construction engineering firm Fluor Corp. (NYSE: FLR) is adding repair and maintenance company Stork Holding BV and Ares Management LP (NYSE: ARES) along with Harvest Partners LP have acquired waste management services company Valet Waste.