NAICS Codes for Construction Contractors: Complete 2026 Guide

NAICS Codes for Construction Contractors: The Complete 2026 Reference

Every government construction bid starts with a six-digit number that determines whether you are eligible to compete. That number is your NAICS code — the North American Industry Classification System code that federal, state, and local agencies use to categorize your business, set contract size thresholds, and award small business set-asides.

Getting your NAICS codes right is not optional. Contractors who register incorrect or incomplete NAICS codes on SAM.gov miss 37% of the federal set-aside opportunities they qualify for, according to SBA procurement data from fiscal year 2025. That translates to billions in contract dollars flowing to competitors who simply classified their businesses correctly.

This guide covers every construction NAICS code, explains how agencies use them for procurement decisions, and walks through the registration process that positions your company for maximum contract eligibility.

What Are NAICS Codes and Why Do They Matter for Construction?

NAICS stands for the North American Industry Classification System. The U.S. Census Bureau, Statistics Canada, and Mexico's INEGI jointly maintain it. Every business in North America falls under a six-digit NAICS code that classifies the type of work it performs.

For construction contractors, NAICS codes serve four critical functions:

1. Federal procurement eligibility — Every federal solicitation designates a NAICS code. Your company must be registered under that code on SAM.gov to bid.
2. Small business size determination — The SBA assigns a revenue threshold (size standard) to each NAICS code. If your average annual receipts fall below the threshold, you qualify as a small business for contracts using that code.
3. Set-aside targeting — Contracting officers use NAICS codes to identify which businesses qualify for small business, 8(a), HUBZone, SDVOSB, and WOSB set-asides.
4. Bid matching and discovery — Procurement portals filter opportunities by NAICS code. Contractors who register the right codes receive relevant bid notifications automatically.

The Three Construction NAICS Series: 236, 237, and 238

All construction NAICS codes fall within Sector 23 (Construction), divided into three subsectors. Understanding these divisions determines which codes apply to your business.

236 — Construction of Buildings

This subsector covers companies that build residential and commercial structures as general contractors, operative builders, or design-build firms.

Who uses 236 codes: General contractors, design-builders, construction managers at risk, and operative builders. If your company holds the prime contract for constructing an entire building, you belong in the 236 series.

237 — Heavy and Civil Engineering Construction

This subsector covers contractors building infrastructure: highways, bridges, utilities, pipelines, and power plants.

Who uses 237 codes: Heavy civil contractors, DOT contractors, utility contractors, pipeline installers, and infrastructure builders. If you bid on FDOT lettings or state DOT projects, 237310 is your primary code.

238 — Specialty Trade Contractors

This is the largest subsector, covering every specialty trade from electrical and plumbing to demolition and site preparation.

Who uses 238 codes: Subcontractors and specialty trade contractors. Electrical contractors, HVAC contractors, plumbers, roofers, concrete contractors, and every other trade specialty. Most specialty contractors register 2-4 codes within the 238 series.

How to Look Up Your Construction NAICS Code

Finding the right NAICS code takes five minutes using one of three official methods:

Common NAICS Code Mistakes to Avoid

Contractors make three costly NAICS code errors:

Mistake 1: Registering only one code. The average federal construction contractor registers 4-6 NAICS codes. A general contractor who only registers 236220 misses set-aside opportunities under 238xxx codes for self-performed specialty work.

Mistake 2: Using outdated codes. NAICS codes are revised every five years. The 2022 revision updated descriptions and examples. Contractors using pre-2017 codes risk misclassification.

Mistake 3: Selecting codes based on aspirational work. Register codes for work you currently perform and can document with past performance references. Claiming a NAICS code for work you have never performed triggers prequalification challenges and potential fraud concerns.

How Federal Agencies Use NAICS Codes for Set-Asides

Understanding how contracting officers use NAICS codes gives you a strategic advantage in government construction bidding.

The Designation Process

For every federal solicitation, the contracting officer selects a single NAICS code that best describes the principal purpose of the contract. This designation determines:

• Size standard — The revenue threshold for small business eligibility
• Set-aside eligibility — Whether the contract can be reserved for small businesses
• Competition pool — Which registered contractors receive notifications

Small Business Set-Aside Thresholds

The SBA reviews all construction NAICS codes annually and adjusts size standards based on industry data. Current thresholds (effective March 2025):

Size standards use a five-year average of annual receipts. If your company's average annual revenue over the past five completed fiscal years falls below the size standard for a specific NAICS code, you qualify as a small business under that code.

Set-Aside Categories That Use NAICS Codes

Federal set-aside programs that reference NAICS codes include:

• Small Business Set-Asides — Available to any business below the NAICS size standard
• 8(a) Business Development — SBA-certified socially and economically disadvantaged firms
• HUBZone — Businesses in Historically Underutilized Business Zones
• SDVOSB — Service-Disabled Veteran-Owned Small Businesses
• WOSB/EDWOSB — Women-Owned and Economically Disadvantaged Women-Owned Small Businesses

Each program requires SAM.gov registration with accurate NAICS codes. The SBA verified 23,400 construction firms for set-aside eligibility in fiscal year 2025.

NAICS vs. SIC Codes: What Contractors Need to Know

The Standard Industrial Classification (SIC) system, created in 1937 and last updated in 1987, was the predecessor to NAICS. While NAICS officially replaced SIC in 1997, some state and local agencies, insurance companies, and financial institutions still reference SIC codes.

Key SIC-to-NAICS Mappings for Construction

If a solicitation or form requests an SIC code, use these common equivalencies:

• SIC 1521 (General Contractors — Residential) → NAICS 236115, 236116, 236117, 236118
• SIC 1522 (General Contractors — Residential, Other) → NAICS 236118
• SIC 1541 (General Contractors — Industrial) → NAICS 236210
• SIC 1542 (General Contractors — Commercial) → NAICS 236220
• SIC 1611 (Highway and Street Construction) → NAICS 237310
• SIC 1731 (Electrical Work) → NAICS 238210
• SIC 1711 (Plumbing, Heating, AC) → NAICS 238220

The Census Bureau maintains a complete concordance table at census.gov/naics that maps every SIC code to its NAICS equivalent.

Registering and Updating NAICS Codes on SAM.gov

SAM.gov (System for Award Management) is the mandatory federal registration for all government contractors. Your NAICS codes in SAM.gov directly determine which contract notifications you receive and which set-asides you qualify for.

How State and Local Agencies Use NAICS Codes

While NAICS codes originated as a federal classification system, state and local agencies increasingly use them for procurement:

State DOTs — Most state departments of transportation reference NAICS codes in their prequalification applications. FDOT, Caltrans, TxDOT, and NYSDOT all use NAICS 237310 (Highway, Street, and Bridge Construction) as a baseline classification.

Municipal procurement portals — Platforms like PlanetBids, BidNet, and DemandStar filter vendor searches by NAICS code. Registering the right codes ensures you appear in agency searches when they solicit construction services.

DBE certification — The Department of Transportation's Disadvantaged Business Enterprise program uses NAICS codes to define the specific types of work a DBE firm is certified to perform. Your DBE certification lists specific NAICS codes, and prime contractors must match subcontractor NAICS codes to contract line items.

State small business programs — Many states mirror the federal small business set-aside structure, using NAICS codes and SBA size standards (or state-specific thresholds) to determine eligibility.

NAICS Codes and Bonding: The Connection Contractors Miss

Your NAICS code selection affects bonding capacity in two ways that most contractors overlook:

Surety underwriting — Surety companies use NAICS codes to classify your work type and assess risk. A contractor registered under 237310 (Highway Construction) faces different underwriting criteria than one under 236220 (Commercial Building). Sureties evaluate your experience history against the NAICS codes you claim.

SBA Surety Bond Guarantee Program — The SBA guarantees bonds for small businesses that qualify under construction NAICS size standards. The program covers bonds up to $6.5 million per contract (individual) and $10 million (total outstanding). Your NAICS-based small business status determines eligibility.

Advanced NAICS Strategy: Maximizing Contract Eligibility

Sophisticated contractors treat NAICS code selection as a strategic business decision, not just an administrative task. Here is how to optimize your NAICS profile:

Register Your Full Capability Scope

A general contractor who self-performs concrete, electrical, and site work should register:

• 236220 — Commercial Building Construction (primary)
• 238110 — Poured Concrete Foundation and Structure Contractors
• 238210 — Electrical Contractors
• 238910 — Site Preparation Contractors

This four-code registration makes you visible for prime contracts (236220) and subcontracting opportunities (238xxx codes). Prime contractors searching SAM.gov for qualified subcontractors filter by specialty NAICS codes.

Monitor NAICS Code Designations on Target Contracts

Track how your target agencies designate NAICS codes on construction solicitations. Some agencies consistently use 236220 for projects that other agencies designate under specialty codes. This affects:

• Which competitors you face (higher size standards attract larger firms)
• Whether the contract qualifies for small business set-asides
• Your eligibility based on past performance under that specific NAICS code

Challenge Incorrect NAICS Designations

If an agency designates a NAICS code that does not match the solicitation's principal purpose, any interested party can file a NAICS code appeal with the SBA Office of Hearings and Appeals within 10 calendar days of the solicitation issuance. This is a legitimate and commonly used process — the SBA processes approximately 150 NAICS code appeals annually, overturning the agency's designation in roughly 30% of cases.

Use NAICS Codes for Market Research

Before entering a new market segment, research the competitive landscape by NAICS code:

1. Search USAspending.gov by NAICS code to see contract award amounts and winning contractors
2. Use FPDS.gov to analyze award patterns by NAICS code, agency, and business size
3. Review the SBA's dynamic small business search (dsbs.sba.gov) to count competitors registered under your target NAICS codes

This research reveals bid opportunities where competition is thin and your qualifications are strong.

NAICS Codes for Emerging Construction Specialties

The construction industry evolves faster than NAICS revisions. Contractors in emerging specialties need to map their work to existing codes until the next revision creates dedicated classifications.

Common Questions About Construction NAICS Codes by Trade

Different trades face unique NAICS code decisions. Here are the most frequent questions by specialty:

General Contractors

Primary code: 236220 (Commercial) or 236115 (Residential)

General contractors face the most complex NAICS decisions because they manage projects across multiple codes. The rule of thumb: use the 236 series for prime contracts where you manage the overall project, and add 238 series codes for any specialty work you self-perform.

Electrical Contractors

Primary code: 238210

Electrical contractors increasingly need secondary codes for solar (also 238210), low-voltage systems (238210), and fire alarm installation (238210). The 238210 code is broad enough to cover most electrical specialties, but contractors doing significant power line construction should add 237130.

HVAC Contractors

Primary code: 238220

HVAC contractors who also perform plumbing work fall under the same 238220 code. Contractors specializing in commercial refrigeration systems should also consider 238220, as the code description covers heating, ventilation, air-conditioning, and refrigeration work.

Concrete Contractors

Primary code: 238110

This covers poured concrete foundations, footings, walls, floors, and structural elements. Contractors who also perform site grading and excavation for foundations should add 238910 (Site Preparation Contractors).

Roofing Contractors

Primary code: 238160

Roofing contractors who also install siding, gutters, or building exterior waterproofing should add 238170 (Siding Contractors) and 238190 (Other Building Exterior Contractors).

NAICS Codes and Bid Matching: Finding the Right Opportunities

Your NAICS codes directly affect which bid opportunities appear in your searches across procurement portals. Here is how to leverage NAICS codes for more effective bid discovery:

Federal Opportunities (SAM.gov / Contract Opportunities)

The federal procurement portal (formerly FBO, now integrated into SAM.gov) allows filtering by NAICS code. Set up saved searches for each of your registered NAICS codes to receive email notifications when matching solicitations post.

State and Local Portals

Most state procurement portals support NAICS code filtering. When registering on state vendor portals, enter every applicable NAICS code — the registration systems use these codes to send automated bid notifications.

AI-Powered Bid Matching

Modern bid aggregation platforms like ConstructionBids.ai use NAICS codes as one input among many for AI-powered matching. The platform cross-references your NAICS codes with project descriptions, geographic preferences, contract size, and historical bid patterns to surface the most relevant opportunities.

Maintaining Your NAICS Codes: Annual Review Checklist

NAICS codes are not a set-and-forget decision. Treat your NAICS profile as a living document that evolves with your business:

1. Annual SAM.gov renewal — Review all registered codes during your mandatory annual renewal
2. Revenue composition check — Verify your primary NAICS code still reflects your highest-revenue activity
3. Size standard verification — SBA updates size standards annually; confirm you still qualify as small under each code
4. New capability addition — When you add a trade capability (e.g., a GC starts self-performing electrical work), add the corresponding NAICS code
5. Market expansion review — Entering new market segments (e.g., highway construction) requires adding the appropriate NAICS code before bidding
6. DBE certification alignment — If DBE-certified, ensure your DBE NAICS codes match your SAM.gov registration
7. Past performance documentation — Maintain contract references for each NAICS code you register; agencies verify experience by code

Final Takeaways for Construction Contractors

NAICS codes are the foundation of your government contracting eligibility. Here is what to do today:

• Audit your current NAICS codes on SAM.gov — verify they cover your full capability scope
• Add missing specialty codes for any trade work you self-perform
• Verify size standard eligibility using your five-year average annual receipts
• Register NAICS codes on state portals — not just SAM.gov
• Set up bid alerts by NAICS code on your primary procurement portals
• Consult your local PTAC for free guidance on code selection and set-aside eligibility

The difference between the right NAICS codes and incomplete registration is the difference between seeing every opportunity you qualify for and missing a third of them. Five minutes of registration work opens doors to billions in annual construction contract awards.

For contractors ready to move beyond manual portal searches, AI-powered bid matching platforms combine your NAICS codes with machine learning to deliver the most relevant opportunities — automatically, daily, across every government level. That is the future of construction bid discovery.