50 Largest mechanical contractors in the U.S.

50 Largest mechanical contractors in the U.S.

Mechanical contractors play an essential role in America’s trillion-dollar construction industry. Keep reading as we explore the largest mechanical contractors in the U.S. based on data from Engineering News-Record (ENR).

Top 50 largest mechanical contractors in the U.S.

Note: The “ENR rank” column indicates each company’s place on the magazine’s list of top 600 contractors in the United States.

Position Company ENR Rank (2020)
1 Comfort Systems USA 9
2 ACCO Engineered Systems 16
3 Southland Industries 20
4 McKinstry 33
5 Nooter 38
6 Apollo Mechanical Contractors 42
7 Harris 43
8 Limbach Holdings LLC 44
9 TDIndustries 45
10 Harder Mechanical Contractors Inc 46
11 The Brandt Cos. 47
12 U.S. Engineering 63
13 McKenney’s Inc. 66
14 MacDonald Miller Facility Solutions 70
15 Pan-Pacific Mechanical 74
16 Integrated Service Co. LLC (InServ) 75
17 JH Kelly 83
18 Murphy Co. Mechanical Contractors and Engineers 88
19 RK Mechanical Inc. 95
20 Critchfield Mechanical Inc. 103
21 Helm Group 111
22 WDF Inc. 113
23 E.M. Duggan Inc. 137
24 John E. Green Co. 145
25 HB Global LLC 146
26 Hermanson Co. LLP 147
27 JB Henderson Construction 152
28 MB Mechanicals Holdings 153
29 Wyatt 158
30 SAUER HOLDINGS Inc. 161
31 Ivey Mechanical Co. LLC 164
32 Dorvin D. Leis Co. Inc. 165
33 KSW Mechanical LLC 173
34 Baker Group 180
35 Arden Building Cos. LLC 190
36 AtlanTic Constructors Inc. 192
37 Southern Air Inc. 195
38 Pacific Rim Mechanical Contractors Inc. 198
39 Fresh Meadow Mechanical Corp. 208
40 MTech Mechanical 210
41 IPS (Industrial Power Systems) 216
42 A.O. Reed & Co. 218
43 Greenberry Industrial LLC 221
44 B&I Contractors Inc. 231
45 Polk Mechanical Co. LLC 232
46 Kimbel Mechanical Systems Inc. 240
47 icon Mechanical 242
48 R.T. Moore Co. Inc. 249
49 W.G. Tomko Inc. 253
50 Charter Mechanical 254

A closer look at the 10 largest mechanical contractors in the U.S.

Next, let’s look at each of the top 10 biggest mechanical contracting companies in America.

#1. Comfort Systems USA

Comfort Systems USA is the country’s leading HVAC, electrical, and plumbing service provider. Based in Houston, Texas, Comfort Systems USA is publicly traded and boasts a market cap of $2.73 as of writing, according to Yahoo Finance.

The company operates in more than 140 locations across the United States through over 35 subsidiaries, including:

  • ACI Mechanical
  • BCH Mechanical
  • ColonialWebb
  • Eastern Heating & Cooling
  • RoyalAire
  • Starr Electric Company
  • TEC Industrial

According to Fortune, Comfort Systems USA employs over 12,000 Americans.

#2. ACCO Engineered Systems

Pasadena, California-based ACCO Engineered Systems is an employee-owned mechanical contracting company founded in 1934. Its services include:

  • energy management
  • engineering support
  • mechanical equipment repairs
  • mechanical retrofits
  • plumbing
  • preventative maintenance

Among ACCO Engineered Systems’ notable projects are Salesforce Tower, The Wilshire Grand Center, and Staples Center.

Owler estimates the company’s annual revenue at $1 billion and its employee count at 3,000.

#3. Southland Industries

Next on our list of the largest mechanical companies in the USA is Southland Industries. The Garden Grove, California-based company reported annual revenue of $940 million in 2020.

Its service offerings include:

  • sheet metal systems
  • HVAC
  • plumbing
  • process piping

Southland Industries has provided these services on countless projects since its founding in 1949. Among them are Arena Stage, Banc of California Stadium, and City Center Aria Tower.

Owler pegs Southland Industries’ headcount at 1,200.

#4. McKinstry

McKinstry is an acclaimed mechanical contractor based in Seattle, Washington. The firm got its start in 1960 as a plumbing contractor. It has since been recognized by ENR and even former U.S. President Barrack Obama as a forerunner among sustainable, environmentally-friendly mechanical contractors.

McKinstry is arguably best-known for its energy services in government, healthcare, and renewables. Owler estimates the company’s annual revenue at $600 million and its headcount at 1,529.

#5. Nooter/Eriksen

Nooter/Eriksen is among the most experienced mechanical contracting companies in the United States, with its amalgamated firms having been founded over 100 years ago. The Fenton, Delaware-based company operates worldwide, with offices in Europe, Asia, and the Middle East. It specializes in supplying heat recovery steam generators but also provides engineering and inspection services.

#6. Apollo Mechanical Contractors

Apollo Mechanical Contractors is a Native American-owned mechanical contractor founded in 1981. The company’s extensive list of service offerings also includes pre-construction, civil engineering, equipment installation, and preventative maintenance.

Apollo Mechanical Contractors provides service in many sectors, such as:

  • high-tech manufacturing
  • food processing
  • industrial manufacturing
  • mission-critical systems

#7. Harris

Our next largest mechanical contractor is Harris, which was founded in St. Paul, Minnesota in 1948. This mechanical contracting company specializes in engineering, construction, and building controls. Harris boasts 11 regional offices and over 2,000 employees.

Its recent projects include the Minneapolis Marriott Southwest Hotel, Reagan National Airport’s new north concourse, and a certain company’s spaceship-shaped corporate campus in Cupertino, California.

#8. Limbach Holdings LLC

Limbach Holdings is a publicly-traded mechanical contracting company specializing in HVAC, electrical, plumbing, and control systems. According to Yahoo Finance, its current market capitalization sits at $114.2 million.

Limbach Holdings is based in Pittsburgh but has offices all throughout the United States, including Southern California. It employs more than 1,500 workers across the country.

#9. TDIndustries

Next on our list of the largest mechanical contractors in the U.S. is TDIndustries. The company, founded in 1946 and boasting $690 million in revenue, specializes in HVAC, mechanical, electrical, and plumbing services.

It’s 100% employee-owned and has ranked on Fortune Magazine’s list of the 100 best companies to work at for over two decades.

#10. Harder Mechanical Contractors

Last but certainly not least on our roundup of the largest mechanical contractors in America, we have Harder Mechanical Contractors. The firm got its start as a plumbing contractor in Portland, Oregon during the city’s massive World War II manufacturing effort. Following the war, Harder Mechanical Contractors continued adapting to the nation’s shifting needs.

Today, the company has locations all over the western United States, specializing in everything from plumbing to process piping, equipment installation, and modularization.

Bridgit Bench is the resource management software of choice for countless mechanical contractors. Visit this page to learn more about how our tools help mechanical contractors of all sizes allocate resources more efficiently. Interested in joining the construction workforce? Check out our construction career development resources here.


Lauren Lake

Lauren Lake is the CCO and co-founder at Bridgit. She holds a degree in Civil Structural Engineering and is well-versed in construction workforce management and resource planning processes. Lauren has been named to the Forbes Manufacturing & Industry 30 Under 30 and Best Of Canada Forbes Under 30 Innovators lists. Lauren has presented at industry events and conferences, including BuiltWorlds, Canadian Construction Association, Procore Groundbreak, and more.

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