NAICS Codes for Construction: All 236-238 Codes (2026)

NAICS Codes for Construction Contractors: Complete Bidding Guide [2026]

NAICS codes determine which federal construction bids your firm receives, whether you qualify for small business set-asides, and how agencies classify your capabilities. The North American Industry Classification System assigns every construction company a six-digit code that controls access to billions in government contracts. Selecting the wrong code costs contractors set-aside eligibility, automated bid notifications, and competitive positioning on federal solicitations.

Construction falls under NAICS Sector 23, which generated $2.1 trillion in U.S. revenue in 2025. The sector splits into three subsectors -- 236 (Building Construction), 237 (Heavy and Civil Engineering), and 238 (Specialty Trade Contractors) -- each with distinct SBA size standards ranging from $16.5M to $45M in average annual receipts.

This guide covers every construction NAICS code, its SBA size standard, SAM.gov registration requirements, and the selection strategy that ensures your firm receives the right bids and maintains set-aside eligibility.

How the NAICS System Works for Construction

The Census Bureau maintains the NAICS system, updating it every five years (most recently in 2022). Every business in the United States receives at least one NAICS code based on its primary revenue-generating activity. For construction contractors, this classification drives three critical outcomes:

1. Federal bid matching -- SAM.gov uses your registered NAICS codes to send automated opportunity notifications
2. Small business eligibility -- Each NAICS code carries an SBA size standard that determines whether your firm qualifies as "small"
3. Agency reporting -- Contracting officers track spending by NAICS code for congressional reporting and small business goal compliance

Unlike product-based businesses that use multiple classification systems, construction contractors rely on NAICS as the single classification standard across federal, state, and most local procurement. Understanding this system is foundational to winning government construction bids and navigating SAM.gov registration.

NAICS 236: Building Construction

NAICS 236 covers establishments primarily responsible for the construction of buildings. These are the general contractors and developers who manage entire building projects, coordinating subcontractors across multiple trades.

Residential Building Construction (NAICS 2361)

Key distinctions within residential codes:

• 236115 applies when you build custom single-family homes on land owned by others (contract builders)
• 236116 covers multifamily apartment and condo construction as a general contractor
• 236117 is for developers who build and sell -- the "spec home" builder model
• 236118 covers residential renovation, addition, and remodeling contractors

Commercial Building Construction (NAICS 2362)

NAICS 236220 is the most widely used code among general contractors pursuing government work. It covers construction of:

• Office buildings and government facilities
• Schools, hospitals, and universities
• Retail and commercial structures
• Religious buildings and community centers
• Renovation of existing commercial structures

The $45M threshold makes NAICS 236 codes the most generous in construction for small business set-aside eligibility. A general contractor averaging $40M in annual revenue qualifies as small under 236220 but would exceed the threshold under most 238 specialty trade codes.

NAICS 237: Heavy and Civil Engineering Construction

NAICS 237 covers contractors who build infrastructure rather than buildings. These projects include highways, bridges, water systems, power lines, and oil pipelines. Heavy/civil contractors typically work on public-sector projects funded by federal and state transportation and utility budgets.

Revenue Concentrations by Code

• 237110 -- Municipal water and wastewater treatment plants, storm drainage systems, water distribution mains, sewer collection systems
• 237310 -- The largest single NAICS code by federal spending volume; covers DOT-funded highway projects, bridge rehabilitation, airport runways, and parking structures
• 237990 -- Catch-all for marine construction, dam construction, flood control projects, and industrial nonbuilding structures

Every 237 code carries a $45M SBA size standard, matching the 236 building construction codes. This uniform threshold simplifies eligibility calculations for heavy/civil contractors who perform work across multiple infrastructure categories.

NAICS 238: Specialty Trade Contractors

NAICS 238 covers contractors who perform a specific construction trade rather than managing entire projects. This is the largest subsector by number of firms -- over 800,000 specialty trade establishments operate in the United States. SBA size standards here are lower than 236 and 237, ranging from $16.5M to $22M.

Foundation, Structure, and Building Exterior (NAICS 2381)

Building Equipment Contractors (NAICS 2382)

238210 and 238220 represent the two highest-revenue specialty trade codes in the U.S. economy. Electrical and mechanical contractors using these codes collectively generate over $350 billion annually.

Building Finishing Contractors (NAICS 2383)

Other Specialty Trade Contractors (NAICS 2389)

238910 covers demolition, excavation, grading, land clearing, and earthmoving -- critical early-phase work on virtually every construction project. 238990 is the catch-all for specialty work not classified elsewhere, including scaffolding, insulation (except building), sandblasting, and welding.

How to Look Up Your Correct NAICS Code

Selecting the right NAICS code requires matching your primary revenue activity to the census definitions. Follow this process:

The primary code matters most because contracting officers use it to determine your firm's principal business activity. However, secondary codes expand your bid notification coverage significantly -- each additional code generates matching opportunity alerts through SAM.gov.

SAM.gov Registration and NAICS Codes

SAM.gov (System for Award Management) is the mandatory registration portal for any contractor pursuing federal work. Your NAICS codes are a required field in the registration and directly control which bid opportunities appear in your notifications.

Registration Requirements

Every SAM.gov entity registration includes:

• Unique Entity Identifier (UEI) -- Assigned by SAM.gov, replacing the former DUNS number
• Primary NAICS code -- The single code representing your dominant revenue activity
• Additional NAICS codes -- Every secondary trade you perform
• Business size -- Self-certification as small or other-than-small under each registered code
• Socioeconomic certifications -- 8(a), HUBZone, SDVOSB, WOSB if applicable

For a detailed walkthrough of the full SAM.gov registration process beyond NAICS codes, see the federal construction bidding guide. If you are new to government contracting entirely, the first-time government contractor guide covers the complete onboarding sequence.

Annual Renewal

SAM.gov registrations expire annually. During renewal:

• Review and update NAICS codes to reflect current revenue mix
• Recalculate three-year average annual receipts for size standard compliance
• Add new codes for trades you have entered since last registration
• Remove codes for work you no longer perform

Failure to renew on time blocks your firm from receiving contract awards until the registration is reactivated.

Using NAICS Codes for Federal Bid Strategy

Strategic NAICS code selection directly impacts your bid pipeline volume and competitive positioning. Here is how experienced contractors leverage the system:

Match Codes to Solicitation Patterns

Federal contracting officers assign one NAICS code per solicitation. Before registering codes, search SAM.gov contract opportunities filtered by each potential code. Evaluate:

• Volume -- How many active solicitations use this code in your geography
• Set-aside frequency -- What percentage of solicitations under this code are small business set-asides
• Dollar range -- Whether the typical contract size matches your capacity and bonding limits
• Competition density -- How many firms register under this code in your area

Leverage Size Standard Differences

The gap between 236/237 codes ($45M threshold) and 238 codes ($19M threshold) creates strategic opportunities. A $25M electrical contractor:

• Qualifies as small under 236220 (Commercial Building, $45M threshold) if they also perform GC work
• Does not qualify as small under 238210 (Electrical, $19M threshold) because they exceed $19M

This contractor benefits from pursuing general contracting set-aside bids under 236220 while bidding full-and-open competitions under 238210. Understanding these dynamics is essential for contractors approaching the small business threshold.

Combine Federal and State Opportunities

While NAICS codes are mandatory for federal work, many state and municipal procurement systems also use them for vendor classification. Platforms like government procurement portal, BidNet, and state procurement portals reference NAICS codes in bid matching algorithms. Consistent code registration across all platforms maximizes your opportunity coverage.

Common NAICS Code Mistakes Construction Contractors Make

After reviewing thousands of SAM.gov profiles, these errors appear repeatedly. Each one costs contractors real bid opportunities.

Mistake #1: Single-Code Registration

The most common error is registering with only one NAICS code. A mechanical contractor who registers only under 238220 (Plumbing/HVAC) misses notifications for 236220 (Commercial Building) solicitations that include significant mechanical scopes, 237110 (Water/Sewer) projects requiring mechanical expertise, and 238290 (Other Building Equipment) opportunities that overlap their capabilities.

Mistake #2: Misunderstanding Size Standard Calculation

SBA size standards use average annual receipts over three completed fiscal years, not current-year revenue. A contractor who earned $12M, $18M, and $24M across three years has a $18M average -- still qualifying as small under all 238 codes ($19M threshold). Contractors who calculate size incorrectly either miss set-aside opportunities they qualify for or bid on set-asides they do not qualify for (risking false certification penalties).

Mistake #3: Ignoring the Primary Code Distinction

Your primary NAICS code determines how agencies categorize your firm in market research. When a contracting officer searches for "small electrical contractors" and filters by 238210, only firms with 238210 as a registered code appear. The primary code also drives the SBA's industry-specific programs and counseling recommendations.

NAICS Codes and Small Business Set-Aside Programs

Federal agencies must award a percentage of contracts to small businesses. These set-aside programs use NAICS codes as the eligibility gateway:

The interaction between NAICS codes and set-aside programs creates significant competitive advantages for firms that plan their code registration strategically. A contractor who qualifies under both 236220 ($45M threshold) and 238220 ($19M threshold) accesses two separate pools of set-aside opportunities with different competitive landscapes.

NAICS Code Quick Reference by Trade

Use this table to find the correct code for your primary construction trade:

Automating NAICS-Based Bid Discovery

Manually searching SAM.gov, state portals, and municipal bid boards for opportunities matching your NAICS codes consumes 8-12 hours per week for the average estimating team. Each platform uses different search interfaces, different update schedules, and different notification systems.

Modern bid management platforms aggregate these sources and match opportunities to your registered NAICS codes automatically. The difference between manual and automated discovery:

ConstructionBids.ai uses your NAICS codes as one of 14 matching parameters to surface relevant opportunities from federal, state, county, and municipal sources. The AI scoring layer evaluates each opportunity against your win history, bonding capacity, geographic preference, and trade specialization -- not just the NAICS code match.

Updating NAICS Codes as Your Business Grows

Construction firms evolve. A specialty electrical contractor ($12M revenue) that starts self-performing general contracting work ($8M revenue) needs to add NAICS 236220 to capture building construction opportunities. A residential remodeler expanding into commercial work transitions from 236118 to 236220 as their primary code.

Review your NAICS code registration when:

• Annual revenue mix shifts by more than 20% between trades
• New service lines launch that fall under a different NAICS code
• Revenue approaches the size standard threshold for your primary code
• SAM.gov annual renewal comes due (set a calendar reminder 60 days in advance)
• Acquisitions or mergers change your firm's primary activity

Strategic code management becomes especially important as contractors grow toward SBA size standard thresholds. Losing small business status under a high-value NAICS code eliminates access to set-aside contracts that smaller competitors cannot win without your firm's capabilities.

NAICS Codes Beyond Federal Contracting

While federal procurement drives the most rigorous NAICS code requirements, the classification system appears across the construction industry:

• Insurance underwriting -- Carriers use NAICS codes to classify risk and set premiums for contractor policies
• Banking and lending -- SBA loans reference NAICS codes for industry-specific lending programs and size eligibility
• State procurement -- Most state DOTs and public works agencies use NAICS codes in their vendor databases
• Industry benchmarking -- Financial ratios, safety statistics, and market data publish by NAICS code
• Tax reporting -- IRS uses NAICS codes on business tax returns for industry classification

Maintaining accurate NAICS codes across all business registrations ensures consistency that strengthens your firm's credibility with agencies, lenders, and bonding companies. For contractors focused on pre-qualification requirements, accurate NAICS classification is a baseline expectation.

Key Takeaways for Construction NAICS Code Selection

Construction NAICS codes are not administrative paperwork -- they are strategic business assets that determine which contracts your firm competes for and whether you qualify for the set-aside programs that reduce competition. Every dollar of revenue traced to a government contract started with a NAICS code match.

Get your codes right. Register them everywhere. Update them annually. Then let automated bid matching handle the rest so your estimating team focuses on winning work instead of finding it.