NAICS 321918

Overview

The North American Industry Classification System (NAICS) is the federal standard for classifying U.S. business establishments to support statistical collection, analysis, and publication. Developed by the Office of Management and Budget in cooperation with Canada and Mexico, NAICS replaced SIC in 1997 and is currently published on the 2022 vintage. ¹

NAICS 321918 — Other Millwork (including Flooring) — covers establishments primarily engaged in manufacturing millwork other than wood windows, wood doors, and cut stock. Illustrative products include wood moldings, trim, stairwork, wood shutters, planing‑mill millwork, and wood flooring. It is a six‑digit U.S. national industry within 32191 (Millwork). ²

• See also on G2X:
  • NAICS 321918
  • NAICS 321911 (Wood Window and Door Manufacturing)
  • PSC 5520 (Millwork)

What this NAICS covers

• Manufacturing clear and finger‑jointed wood moldings (e.g., base, chair rail, crown, shoe). ²
• Producing decorative wood trim and ornamental woodwork (cornices, mantels). ²
• Fabricating wood stairwork and railings, including newel posts and stair components. ²
• Operating planing mills that produce millwork from purchased lumber. ²
• Manufacturing wood shutters and similar architectural millwork. ²
• Manufacturing wood flooring (strip, plank, parquet). ²

Related NAICS and PSC codes

Type	Code	Descriptor
NAICS	321911	Wood Window and Door Manufacturing
NAICS	321912	Cut Stock, Resawing Lumber, and Planing
PSC	5520	Millwork
PSC	5510	Lumber and Related Basic Wood Materials

Small business size standard

For NAICS 321918, SBA’s small business size standard is 500 employees (employee‑based), effective March 17, 2023. ³

Common exclusions and cross‑references

• Wood windows and wood doors are classified under NAICS 321911. ²
• Cut stock, resawing, and planing purchased lumber are classified under NAICS 321912. ²
• Flooring installation services are construction activities classified under NAICS 238330 (Flooring Contractors), not manufacturing under NAICS 321918. ⁴

Frequently asked questions

• What products are included in NAICS 321918?

  • Census includes millwork such as wood moldings, trim, stairwork, shutters, planing‑mill millwork, and wood flooring. Wood windows, wood doors, and cut stock are excluded and covered by other industries. ²

• How does NAICS 321918 differ from NAICS 321911 and NAICS 321912?

  • 321918 covers “other” millwork (e.g., moldings, stairwork, flooring). 321911 covers wood windows and doors, and 321912 covers cut stock, resawing, and planing purchased lumber. ²

• What is the SBA small business size standard for NAICS 321918?

  • SBA’s table lists 500 employees as the size standard for this manufacturing industry; the current thresholds became effective March 17, 2023. ³

• Are flooring installation services included in NAICS 321918?

  • No. Installation of hardwood and other flooring is construction under NAICS 238330 (Flooring Contractors). NAICS 321918 covers manufacturing of wood flooring and other millwork. ⁴

• Where can official economic statistics for this industry be found?

  • The 2022 Economic Census publishes manufacturing statistics using 2022 NAICS, including industries in Sector 31–33 such as NAICS 321918. ⁵

Useful resources

• G2X — NAICS 321918
• U.S. Census Bureau NAICS industry definition for 321918 (Other Millwork including Flooring). ²
• 2022 Economic Census — Sector 31–33 Manufacturing tables and documentation. ⁵
• SBA Table of Small Business Size Standards (effective March 17, 2023). ³
• NAICS overview and 2022 vintage guidance. ¹

References

1. U.S. Census Bureau. NAICS — North American Industry Classification System (2022 vintage overview). https://www.census.gov/naics/
2. U.S. Census Bureau. 2022 NAICS Code 321918 — Other Millwork (including Flooring) (industry definition). https://www.census.gov/naics/?input=321918&year=2022&details=321918
3. U.S. Small Business Administration. Table of Small Business Size Standards. https://www.sba.gov/document/support--table-size-standards
4. U.S. Census Bureau. 2022 NAICS Code 238330 — Flooring Contractors (industry definition). https://www.census.gov/naics/?input=238330&year=2022&details=238330
5. U.S. Census Bureau. Economic Census — Official program site. https://www.census.gov/programs-surveys/economic-census.html