NAICS Codes for Construction and Contractors in Federal Contracting

A NAICS code is the six-digit label a US contracting officer attaches to every solicitation to say which industry the work belongs to. For a general overview of the system, see our NAICS codes guide. For builders the code does two concrete jobs. It sets the SBA size standard that decides whether you can bid as a small business, and the codes in your SAM.gov registration control which projects agencies find you under when they run market research.

Construction is one of the largest single categories of federal and state spending, and the work splits cleanly into three families: putting up buildings, building infrastructure, and the specialty trades that do one part of a job. Each family sits in its own subsector with its own size standard, so the code on a solicitation changes who counts as small even between two similar projects.

There are two distinct places NAICS codes act on you, and confusing them is the most common early mistake. The codes you register in SAM.gov describe your business and populate the Dynamic Small Business Search that agencies mine for sources-sought responses. The single code on a given solicitation governs that specific award, including which size standard applies and whether a set-aside is open to you. When an officer searches for a general contractor, they filter by NAICS first, so a missing code can quietly keep you off the shortlist for work you could easily deliver. Keeping the codes right is also what keeps your federal bid alerts accurate.

Every construction NAICS code rolls up into one of three subsectors, and knowing which one your work sits in is the fastest way to narrow the code.

236, Construction of Buildings, is for firms that take responsibility for a complete building, whether new work, additions, alterations, or remodeling. General contractors and design-build firms live here. It includes residential codes like 236115 for new single-family housing and 236118 for residential remodelers, plus 236210 for industrial buildings and 236220 for commercial and institutional buildings.

237, Heavy and Civil Engineering Construction, is for infrastructure rather than buildings: highways and bridges under 237310, water and sewer lines under 237110, power and communication lines under 237130, oil and gas pipelines under 237120, and land subdivision under 237210. If the deliverable is a structure people move through or utilities flow through rather than occupy, it is usually a 237 code.

238, Specialty Trade Contractors, is for firms that perform one trade on a project directed by someone else, such as electrical under 238210, plumbing and HVAC under 238220, roofing under 238160, masonry under 238140, or site preparation under 238910. A specialty trade contractor can work for a general contractor as a subcontractor or directly for the owner. Reading the official Census NAICS descriptions before you commit matters, because the wording, not your marketing language, is what a contracting officer matches against.

Most federal construction work concentrates in a handful of codes. 236220, Commercial and Institutional Building Construction, is the default for a general contractor building offices, schools, hospitals, or other non-residential structures, and it is the single most common construction code on federal awards. 236210 covers industrial buildings such as plants and warehouses. On the residential side, 236115, 236116, and 236117 split new single-family, new multifamily, and for-sale builders, while 236118 covers remodelers.

In heavy and civil work, 237310 for highways and bridges and 237110 for water and sewer lines carry the bulk of infrastructure dollars, with 237130 for power and communication lines close behind. Among the specialty trades, the high-volume codes are 238210 electrical, 238220 plumbing and HVAC, 238110 poured concrete foundations, 238160 roofing, and 238910 site preparation. Pick the code that matches the primary purpose of the specific contract, not the broadest description of your company. If your EU work matters too, the parallel classification is covered in our CPV codes for construction guide.

Every NAICS code has an SBA size standard that defines the largest a firm can be and still count as small. Construction standards are measured in average annual receipts, and since the Small Business Runway Extension Act took effect the calculation uses a five-year average rather than three years. Building construction under the 236 codes and heavy and civil work under the 237 codes both sit at 45 million dollars, one of the more generous thresholds in the whole table. The specialty trades under the 238 codes sit lower, at 19 million dollars, because those firms are typically smaller and more focused.

Two exceptions run higher than their subsector. Land subdivision under 237210 and the dredging exception under 237990 carry their own elevated standards, so check them directly rather than assuming the 45 million dollar figure. You can confirm any number against the SBA size standards table, which is the authority when a size protest lands and which SBA adjusts for inflation from time to time. Remember that receipts count across your whole corporate family, so an affiliate or parent's revenue can push you over the line even if your own crew is small, and that the same firm can be small on a 236 solicitation yet large on a 238 one. That is why the code the contracting officer chose for a specific opportunity, not your general self-image, governs eligibility for a small business set-aside.

A solicitation carries exactly one NAICS code, and the contracting officer chooses it under FAR 19.102 to describe the principal purpose of the work. That choice sets the size standard and, on a set-aside, who may bid. It is not automatic that a big building job takes a 236 code. If the scope is dominated by one trade, an officer may code it under a 238 specialty code instead, which changes the size standard from 45 million to 19 million dollars and can shift which firms qualify as small.

The practical lesson is to read the assigned code on every opportunity before you decide to bid, rather than assuming it matches how you describe yourself. If you believe the officer picked the wrong code, there is a formal process to challenge the NAICS assignment before the offer deadline, and winning that challenge can reopen a set-aside or change the competitive field. Understanding this is part of learning how to bid on government contracts cleanly, and it matters more in construction than in most sectors because the same building can plausibly sit under two different subsectors.

You are not limited to one code. Register a primary code, the industry you self-certify your size under, plus a set of secondary codes so you appear in more agency searches. A practical sequence works like this:

1. Pick your primary from where the bulk of your revenue sits. For most general contractors that is 236220, for a paving firm 237310, for an electrical sub 238210.

2. Add secondaries for adjacent work you genuinely self-perform, for example 238910 site preparation if you also clear and grade, or 236210 if you take on industrial buildings.

3. Check the size standard on each code and confirm you qualify as small where it matters, using the SBA table.

4. Mirror the codes agencies actually use for your kind of project, which you can see in award histories and in a federal market intelligence tool.

5. Review yearly, because a growing firm can cross a size standard and a new code can open a set-aside lane. Keeping codes current also protects the accuracy of your e-procurement searches and any PSC code pairings you use to refine results. If you are new to federal registration, our SAM.gov glossary explains how the self-certification fields fit together.

A handful of errors show up again and again, and each one costs opportunities. The first is registering too few codes. A general contractor that lists only 236220 will never surface in a search for 237310 highway work it could handle, even with the crews to do it. The second is registering many unrelated codes to look bigger, which dilutes your relevance in searches and invites size challenges if you win outside your real capability.

The third is treating the primary code as permanent. As your revenue mix shifts from, say, remodeling into new commercial work, the code you self-certify under should move with it. The fourth is ignoring the code an officer put on a solicitation and bidding as small when that particular subsector's standard says you are not, which is grounds for a protest. The fifth is confusing the general contractor role with a specialty trade: if you self-perform only one trade on a job someone else directs, you are a 238 contractor on that work, not a 236 one, and coding it wrong misrepresents your size class. Fix all five by reviewing your registration against your last year of contracts, reading the Census NAICS definitions rather than guessing, and pairing your codes with PSC codes so buyers who search by product and service classification also find you. Firms scaling past the small business line often pair this review with a small business contracting strategy.

Once your codes are set, the daily problem is coverage. SAM.gov shows solicitations under your codes, but construction work is routinely mis-coded, and a building job with heavy sitework can be posted under a 237 or even a 238 code by a busy contracting officer. Filtering by NAICS alone quietly misses those. Federal notices are also only part of the market, since a large share of construction spending runs through state, county, and municipal portals that SAM.gov never touches.

Jorpex tracks SAM.gov alongside more than 50 other public sources, including state and local portals, and matches opportunities with embedding-based semantic AI, so a relevant project surfaces even when its NAICS code is off. You combine NAICS filters with keywords, contract value bands, and disqualifiers to cut noise, then receive matches in Slack, Microsoft Teams, or email as realtime, daily, or weekly digests. Plans start at 49 dollars a month with a 14-day free trial. For the wider picture on winning public work as a builder, see our construction tenders and government contractors guides.