M&O Insulation established in 1972
- 1975: Company expansion, new office in Peoria, Illinois opened
- 1984: Rich O’Heir acquires Jack McNamara’s ownership share, taking sole ownership
- 1987: M&O Environmental established, now offering environmental solutions
- 2020: M&O Atlantic is founded, extending the company’s presence to the East Coast
- 2025: M&O successfully completes its first $100 million single insulation project