If you are building a new dietary supplement manufacturing facility, the time to check it against GMP is while the walls, drains and air handling are still on paper. FDA does not approve facility plans. Its own consumer guidance says "the agency does not approve manufacturing facilities independently. The FDA inspects regulated facilities to verify they comply with applicable current good manufacturing practices." So the first time a regulator judges your building may be an inspection after you are already making product. A pre-construction GMP assessment reads your drawings against 21 CFR Part 111 while a change still costs a revision instead of a renovation.
What does 21 CFR 111 require of the building?
Part 111 describes what the physical plant must achieve, mostly in §111.20 (design and construction) and §111.15 (sanitation), with equipment requirements in Subpart D. These are the requirements a pre-construction review checks the drawings against.
| Requirement | Rule | What to check in the drawings |
|---|---|---|
| Size and layout that allow cleaning, with "adequate space for the orderly placement of equipment and holding of materials" | §111.20(a), (b) | Clearances around equipment, and staging space that does not spill into walkways |
| Separate or defined areas, or other control systems, for seven operations | §111.20(c) | Receiving and holding; material awaiting review, reprocessing or disposal; different product types; the lab; cleaning contact surfaces; packaging and labeling; holding |
| Floors, walls and ceilings "that can be adequately cleaned," and no contamination from fixtures, ducts and pipes "by dripping or other leakage, or condensate" | §111.20(d)(1)(i), (ii) | Finishes, and what runs overhead in production and packaging |
| Ventilation to minimize odors and vapors, and temperature and humidity control "when such equipment is necessary" | §111.20(d)(1)(iii), (iv) | Air handling for dusty or humid operations, and storage conditions |
| Aisles and working space wide enough to work without contaminating product | §111.20(d)(1)(v) | Room between equipment and walls |
| Adequate light, and safety-type bulbs and fixtures over exposed product | §111.20(e), (f) | Lighting in processing, cleaning, restroom and hand-washing areas |
| Pest protection "where necessary" | §111.20(h) | Screening, doors and dock seals |
| Water "safe and sanitary," and component water that meets applicable federal, state and local requirements, with records | §111.15(e), §111.23(c) | Water source, treatment, and sampling points |
| Floor drainage where floors get flood-type cleaning, and no backflow or cross connection | §111.15(f) | Drains, slopes and backflow prevention |
| "Adequate, readily accessible bathrooms" and adequate, convenient hand-washing | §111.15(h), (i) | Locations relative to production entries |
| Equipment installed so it and "all adjacent spaces" can be cleaned, and made of corrosion-resistant, nontoxic materials with smoothly bonded seams | §111.27(a)(3), (4) | Equipment layout and materials of construction |
| Cold storage with an automated temperature control or alarm | §111.27(a)(5) | Refrigerated and frozen storage |
| Compressed air or gases treated so they do not contaminate product | §111.27(a)(7) | Air compressors, filtration and drops |
| Holding "under appropriate conditions of temperature, humidity, and light" | §111.455 | Warehouse climate control and monitoring |
What Part 111 does not tell you
This surprises people who come from pharmaceuticals. Part 111 names no cleanroom class, air-change rate, HEPA requirement or pressure differential, and it sets no number for temperature, humidity or light. It does not name a water standard or a surface finish.
When FDA finalized the rule in 2007, it removed proposed language about "smooth and hard" surfaces. The preamble explains that "the final rule gives you the flexibility to determine how best to construct your facility." It also says you can make multiple products "in the same room or area instead of using a physically separate location, as long as you have systems in place to prevent contamination and mixups."
That flexibility cuts both ways. Nobody hands you a specification, so when an investigator asks why your layout prevents contamination and mixups, the answer has to come from you. In my view, the value of a pre-construction assessment is that you write that answer down before the concrete is poured rather than after.
What I would look at in a set of drawings
- How materials and people move. Trace incoming components from the dock through quarantine, release, production, packaging and finished-goods hold. Look for the places where released and unreleased material, or two product types, share space without a control that keeps them apart.
- Shared air handling. FDA's small entity compliance guide for Part 111 tells manufacturers to "consider possibilities for indirect contamination (e.g., whether contamination could spread to areas through common air handling units or ducts)." Dusty operations such as blending and encapsulation deserve a hard look at what air they share with packaging.
- Water at the point of use. FDA's preamble says the water requirement "applies to water at the point of use, i.e., after it has passed through your plumbing system." It adds that "a yearly municipal report is a good starting point... however, such a report cannot stand on its own." Plan where you will sample.
- Space for quality control. Part 111 lists laboratory work and holding samples among the operations that need a defined area. Quality control also has to approve changes to equipment controls, including software for computer-controlled processes (§111.30). Make room for both in the plan.
- Drains, ceilings and anything overhead. Pipes, ducts and light fixtures over open product are the easiest things to get right on paper and the most expensive to move later.
- Cold storage and alarms. If any component needs refrigeration, plan the automated temperature control or alarm that §111.27 requires.
Put FDA registration on the construction schedule
A dietary supplement plant is a food facility for FDA registration purposes. 21 CFR 1.230(a) says "you must register before your facility begins to manufacture, process, pack, or hold food for consumption in the United States." Registration is not approval, though. §1.242 says it "does not in any way convey FDA's approval or endorsement of a facility or its products."
As of September 2026, Part 111 has not been amended since it was finalized in 2007, so a design checked against it today is being checked against the rule investigators use.
How Certify Consulting Group helps
At Certify Consulting Group, I do pre-construction GMP assessments for dietary supplement manufacturers. I review the drawings and the planned process flow against 21 CFR 111 and mark what needs to change before construction is finished. Then I help with the quality system implementation the new plant needs on its first day of production: the procedures, records and specifications Part 111 expects. Start with our dietary supplement GMP services or the 21 CFR 111 compliance checklist, or book a call.
Jared Clark
Principal Consultant, Certify Consulting
Jared Clark is the founder of Certify Consulting, helping organizations achieve and maintain compliance with international standards and regulatory requirements.