NAICS code for construction: picking the right six-digit code

This page is for construction owners and office managers who need a code for a form (SAM.gov, a vendor portal, a bank, insurer or surety, a tax return), and for anyone building a list of construction companies by code. It covers the NAICS 2022 codes, how to choose, the SIC equivalents, Census counts and federal size standards.

How the construction codes are organized

Sector 23 has three subsectors, split by who is responsible for the work:

The Census Bureau's sector definition puts construction managers (agency and at-risk), design-builders and turnkey contractors with the general contractors. Specialty trades produce "a specific component" of a project, usually on subcontract, though in remodeling they often work for the owner directly.

The six-digit codes for buildings and heavy civil work

For contractors who run the whole project, the code depends on the type of structure:

Specialty trades have 19 six-digit codes in four groups (2381 structure and exterior, 2382 building equipment, 2383 finishing, 2389 other trades). See the pages for plumbing, electrical and concrete contractors.

How to choose: the edge cases

NAICS classifies a business by its primary activity: pick the code for the work that brings in the most revenue, and list the others as secondary codes.

The warehouse, power plant and build-to-rent rows come straight from the Census cross-references.

The SIC codes for construction

The 1987 SIC system puts construction in Division C: Major Group 15 for building contractors and operative builders, 16 for heavy construction, 17 for special trades. From the Census concordances:

The mapping is rarely one to one: 236220 draws on six SIC codes, and SIC 8741, Management Services, scatters its construction management work across ten construction codes. If someone asks for "the SIC code for general construction", there isn't one: give 1542 for commercial work, 1521 for houses, or 1531 for a for-sale builder. The SEC uses its own SIC list, which adds group codes such as 1520, 1540, 1600 and 1700 that aren't in the 1987 manual. UK Companies House forms use UK SIC 2007 instead: 41201 for commercial buildings and 41202 for domestic buildings.

How many businesses use these codes

County Business Patterns counted 814,557 construction establishments with paid employees in 2023, employing 7,659,459 people with an annual payroll of $586.6 billion. Most are small:

The top states by establishments are California (86,763), Florida (68,008), Texas (56,287), New York (51,349) and Illinois (29,457). Commercial building is where the larger firms are: 2,476 of the 39,072 establishments in 236220 (6.3%) have 50 or more employees, against about 0.5% of the 60,635 single-family builders in 236115.

CBP counts locations with paid employees, so a contractor with three offices counts three times and owner-operators with no staff aren't counted. It uses NAICS 2017 codes, but no construction code changed in 2022. Census withholds the largest size classes for 236115 and 236118, so their bands sum to one or two less than the total.

SBA size standards for construction codes

Each code carries an SBA size standard, measured on average annual receipts over your latest five complete fiscal years, including affiliates:

From 13 CFR 121.201, effective March 17, 2023 and unchanged in the eCFR as of 28 October 2026. The gap matters: a firm can be small as a general contractor and too big for a trade set-aside.

Where the code is used, and what a wrong one costs

• SAM.gov and federal bids. List every code you'd bid under. Each solicitation carries one NAICS code, and you must be under its size standard (13 CFR 121.402). A wrong code can be appealed to SBA's Office of Hearings and Appeals within 10 calendar days of the solicitation (13 CFR 121.1103).
• Size certification. Registering to be considered for small business awards counts as certifying your size (13 CFR 121.108), so a code that makes you look small when you aren't is a legal problem, not a typo.
• Tax returns. Schedule C uses the IRS's own list, which shortens some codes: 236100 for residential building, 236200 for nonresidential, 237100 for utility systems. Trade codes keep all six digits.
• Banks, insurers and sureties. They compare you with firms in the same code, so give the one that matches the work you'd describe to an underwriter.

Finding construction companies by code

For public companies, EDGAR lists SEC registrants by SIC code: 1531 operative builders, 1540 nonresidential contractors, 1600 heavy construction and 1731 electrical work. Those lists include subsidiaries and inactive filers. The largest by reported revenue:

Most construction firms are private. State contractor license files and building permits name real, active ones; the guide to construction company lists shows where to get them. Bebop can also search by description, such as commercial general contractors with 20 to 99 employees in one state, and explain why each company fits.

Worked example

Illustrative example. The company and figures are invented.

Ridgeline Builders (ridgeline.example) does commercial tenant fit-outs (60% of revenue), residential remodels (25%) and electrical work for other contractors (15%). Its codes: 236220 as primary, with 236118 and 238210 as secondary codes in SAM.gov.

Its receipts for the last five fiscal years were $11.2 million, $13.5 million, $16.0 million, $19.8 million and $24.5 million: $85.0 million in total, an average of $17.0 million. That's small under 236220 and 236118 ($45.0 million) and under 238210 ($19.0 million).

If next year brings $28.0 million, the oldest year drops out: $85.0 million, less $11.2 million, plus $28.0 million is $101.8 million, or $20.4 million a year. Ridgeline stays small for general contracting set-asides but not for electrical ones, so it should stop bidding 238210 set-asides before that year closes, not after a size protest.

Next step: see how many construction firms there are by trade and size, and where to get their names, in the list of construction companies.