8(a) Federal Construction Services: NAICS 236220 vs. 332311, Explained

The NAICS code on a modular requirement decides which 8(a) federal construction services can be bought sole-source, and at what ceiling. Get it right and the award moves in weeks. Get it wrong and the package bounces between the contracting office and SBA. This post compares the two codes that govern most federal modular buys, using Specialized Testing and Construction (STC), an 8(a) certified contractor that carries both, as the reference vendor.

Why the NAICS Choice Matters More Than It Looks

Under FAR 19.804-2, the 8(a) sole-source ceiling is $4.5 million for services and supplies and $7 million for manufacturing. NAICS 332311 (Prefabricated Metal Buildings and Components) is a manufacturing code, so a requirement classified under it carries the $7 million ceiling. NAICS 236220 (Commercial and Institutional Building Construction) is a construction code and carries the $4.5 million ceiling.

That difference is not academic. A $5.8 million modular requirement is over the sole-source line as a construction buy and comfortably under it as a manufacturing buy. The classification has to be honest, the code must describe the principal nature of the work, but many modular requirements legitimately fit either, and the choice belongs to the contracting officer.

The code also follows the project after award: it drives the size standard, the subcontracting rules, and how the award reports against the agency’s small disadvantaged business goals. Five minutes of classification discipline up front buys a clean file all the way to close-out.

Eligibility mechanics live at 13 CFR 124.503, and STC’s full award walkthrough is on the /sba-8a page.

What NAICS 236220 Covers

The construction code fits requirements where the dominant work happens at the site. Think of a modular building with significant site development: demolition, excavation, grading, foundations, utility tie-ins, ramps, decks, and commissioning. The modules are an input; the deliverable is a constructed facility on federal land.

236220 is the default for permanent modular construction on pier-and-beam or slab foundations, for renovation-plus-addition scopes, and for any project where the agency wants a general contractor responsible for everything inside the fence line. It is STC’s primary NAICS.

What NAICS 332311 Covers

The manufacturing code fits requirements where the deliverable is the building itself as a manufactured product: steel-framed modular units fabricated in a factory, shipped, and set. Site work is incidental, and the value sits in fabrication, factory-installed electrical and mechanical packages, and specialized enclosure work such as hardened or SCIF-grade construction.

332311 is the natural fit for relocatable buildings, for multi-unit fleet buys, and for requirements where the agency separately handles site preparation. It also carries the higher $7 million sole-source ceiling, which matters for larger fabrication-heavy scopes.

Factory-installed, UL-listed electrical assemblies and mechanical packages are the signature of this classification: the more of the building that leaves the factory finished, the stronger the manufacturing logic.

The Threshold Math, with Worked Examples

Three quick scenarios show how the classification plays out.

• A $3.2 million administrative building with full site development: under both ceilings, so classify on the merits. The work is site-dominant, 236220, and the sole-source path is open either way.
• A $5.8 million three-unit secure facility buy, factory-fabricated and set on an existing lot: over the construction ceiling, under the manufacturing ceiling. If the value sits mainly in fabrication, 332311 keeps the direct award available; as a 236220 buy the requirement must compete among 8(a) firms.
• A $9 million campus with buildings, utilities, and roads: over both ceilings. The requirement competes, though restricting competition to 8(a) firms keeps the award inside the program.

The pattern: the classification question only becomes decisive in the band between $4.5 million and $7 million, but in that band it is the whole ballgame.

How to Decide: Three Questions

• Where does the money go? If most of the contract value is factory fabrication, the requirement reads as manufacturing under 332311. If most of it is site development, foundations, and installation labor, it reads as construction under 236220.
• What is the deliverable on paper? A facility accepted on site after commissioning leans 236220. Manufactured units accepted at delivery lean 332311.
• Does the ceiling bind? Run the government estimate against both thresholds before drafting the offer letter. If the estimate clears $4.5 million but not $7 million, confirm with counsel and SBA that a manufacturing classification honestly describes the work.

When the answer is unclear, ask. SBA’s district staff resolve NAICS questions on 8(a) offers routinely, and getting the answer in writing before the offer letter moves is cheaper than a returned package.

One more practical note: the NAICS on the offer letter also sets the small business size standard the participant must meet, so a code change late in drafting is not cosmetic. Settle it before the package routes.

Where STC’s Additional NAICS Codes Fit

Modular requirements rarely arrive clean. A building buy often carries site utilities, electrical distribution, or demolition that could justify its own code. STC carries seven additional NAICS beyond the two primary codes, including 237310 (Highway, Street, and Bridge Construction) and 238110 (Poured Concrete Foundation and Structure Contractors), with 238190, 238290, 238990, 321992, and 531120 on file, which lets a contracting officer keep mixed scopes under one award instead of splitting the requirement into multiple procurements.

The rule of thumb: classify by the principal purpose of the requirement, then confirm the vendor carries that code plus the incidental ones. STC’s full code list is in the vendor record above and on the capabilities page.

One Vendor, Both Codes

The cleanest way to neutralize the NAICS question is a contractor certified under both codes, so the requirement can be classified on its merits rather than around the vendor. STC’s record:

• Legal name: Specialized Testing and Construction · DBA STC
• UEI: E5KCB1AL71J7 · CAGE: 97SC3
• Primary NAICS: 236220 · Secondary NAICS: 332311
• Additional NAICS on file: 237310, 238110, 238190, 238290, 238990, 321992, 531120
• SBA 8(a) status: certified May 27, 2022 · program exit May 27, 2031
• SAM.gov: active · federal contractor in good standing
• Bonding capacity: $5 million single project · $10 million aggregate
• Headquarters: Crowley, Texas · service in all 50 states and U.S. territories

What This Looks Like in Practice

STC’s federal work spans both classifications. The Tinker AFB facility, a 5,680 square foot ICD/ICS 705 compliant building with full site work, decks, and ramps, is the shape of a 236220 project. A multi-building fabrication scope like STC’s three-unit Department of Energy delivery in Las Vegas shows where 332311 logic applies, with three factory-built ICD/ICS 705 compliant units set on an existing parking lot.

Either classification ends at the same place: a commissioned building, a complete close-out file, and a warranty obligation that survives the award. The code question is about how the award begins, not how the building performs.

For a contracting officer, the takeaway is short: classify the requirement by where the work actually happens, check the estimate against the matching ceiling, and verify the contractor carries the code before the offer letter moves. A companion post in this series covers what the design-build model adds once the classification is set.

Need a NAICS Answer for a Live Requirement?

Submit a briefing request. STC responds within one business day with preliminary scope, the classification logic, and a schedule range.