CHARLOTTESVILLE, Va., March 15, 2021 /PRNewswire/ -- Quad-C Management, a leading middle market private equity firm, today announced that it has closed on the acquisition of SEI Group LLC ("SEI" or the "Company") from Narrow Gauge Capital. SEI is a leading distributor and installer of residential building products in the single-family and multi-family residential markets throughout the Southeast. In addition, the firm announced that insulation industry veterans, Joe Carrington and Sean Cusack, have joined the Company as CEO and CFO, respectively, to pursue an aggressive consolidation strategy in the sector.