PE-3(7): Physical Barriers

PE-3(7) requires you to limit access to facilities and protected areas by using physical barriers (walls, doors, cages, mantraps, turnstiles, locked racks) that prevent unauthorized entry and force access through controlled points. To operationalize it fast, define your restricted zones, install or validate barriers at every boundary, and keep inspection, access, and maintenance evidence ready for assessors. (NIST SP 800-53 Rev. 5 OSCAL JSON)

Key takeaways:

• Physical barriers must create real boundaries around defined restricted areas, not just signs or “policy-only” controls. (NIST SP 800-53 Rev. 5 OSCAL JSON)
• Your evidence burden is ongoing: diagrams, inventories, inspection logs, exception approvals, and work orders matter as much as the locks. (NIST SP 800-53 Rev. 5 OSCAL JSON)
• Treat third-party-managed sites (colos, MSP floors, offsite storage) as in-scope if they host your covered system components or sensitive media. (NIST SP 800-53 Rev. 5)

PE-3(7): Physical Barriers is a small line of text with a big operational footprint: “Limit access using physical barriers.” (NIST SP 800-53 Rev. 5 OSCAL JSON) For a CCO or GRC lead, the fastest path to compliance is to translate that sentence into three things an assessor can verify on-site or via evidence: (1) you defined the areas that require protection, (2) you installed barriers that actually restrict movement into those areas, and (3) you run the barriers as a managed control with inspections, maintenance, and documented exceptions.

This requirement typically lands in the middle of competing priorities: security wants “good enough” controls, facilities wants minimal disruption, and IT wants uptime. Your job is to establish a defensible baseline that matches your system boundary and data sensitivity, then prove it operates consistently. If you handle federal information or run a system assessed against NIST SP 800-53, assume assessors will test the physical path to your sensitive assets, not just read your policy. (NIST SP 800-53 Rev. 5)

This page gives you requirement-level guidance you can execute: scope, design decisions, step-by-step implementation, and the evidence package that reduces audit friction.

Regulatory text

Requirement (verbatim excerpt): “Limit access using physical barriers.” (NIST SP 800-53 Rev. 5 OSCAL JSON)

Operator interpretation (what you must do):

• Identify the facility spaces and sub-areas that contain covered system components, sensitive media, or security infrastructure.
• Put physical barriers at the boundaries of those spaces so people cannot enter without going through a controlled entry point.
• Operate barriers as a control: monitor condition, fix failures, and document exceptions. (NIST SP 800-53 Rev. 5 OSCAL JSON)

PE-3(7) is not satisfied by “employees know where they can go” or by cameras alone. Cameras detect; barriers prevent. You can pair barriers with monitoring, but the requirement is explicit about barriers. (NIST SP 800-53 Rev. 5 OSCAL JSON)

Plain-English requirement: pe-3(7): physical barriers requirement

You need hard, physical separations that stop casual or opportunistic access to areas where sensitive assets live. A closed, locked door is a barrier. A badge reader on an open doorway without a door is not a barrier. A locked rack or cage is a barrier when you can’t fully restrict the room. A front desk sign is not. (NIST SP 800-53 Rev. 5 OSCAL JSON)

A useful mental model for implementation: barriers create boundaries; access control governs the gates in those boundaries. PE-3(7) is about the boundaries.

Who it applies to (entity and operational context)

PE-3(7) applies when your organization is implementing NIST SP 800-53 controls for:

• Federal information systems, or
• Contractor systems handling federal data (including systems in commercial environments and third-party facilities). (NIST SP 800-53 Rev. 5)

Operationally, expect scope in any location that houses:

• Production infrastructure (servers, network gear, HSMs, backups).
• End-user device storage where devices contain regulated data.
• Security tooling or logs (SIEM storage, video retention appliances, access control servers).
• Sensitive media (paper records, removable media, backup tapes).
• Network demarcation points and building distribution frames. (NIST SP 800-53 Rev. 5)

Third parties matter because they often provide the most “physical” parts of your environment: colocation data centers, managed office spaces, offsite shredding, records storage, and logistics. If the third party hosts in-scope assets, your compliance posture depends on their barriers and your ability to evidence them. (NIST SP 800-53 Rev. 5)

What you actually need to do (step-by-step)

1) Define your protected areas (scope and boundaries)

Create a short list of restricted zones, such as:

• Data center / server room
• Network closet / MDF / IDF
• Secure media storage
• Security operations room (if it stores sensitive logs or incident material)

For each zone, document:

• Address and floor/room identifier
• What assets are inside (systems, racks, media types)
• Who needs access (role-based, not name-based)
• The physical boundary (door, cage, locked rack) (NIST SP 800-53 Rev. 5 OSCAL JSON)

2) Choose barrier types that match your environment

Use a simple decision matrix:

Environment constraint	Acceptable barrier pattern	Notes for assessors
Dedicated server room	Solid door + commercial-grade lock + controlled key/badge	Door must self-close; avoid “propped open” culture.
Shared room (multi-team)	Interior cages or locked cabinets/racks	Show how you prevent reach-in access to your gear.
Open office with sensitive media	Locking file cabinets in locked room	Prove both cabinet and room are controlled.
Third-party colo	Provider mantrap/turnstile + your locked cage	Your cage boundary is the barrier you can evidence consistently.

Your goal: a person cannot physically reach the protected assets without passing a barrier you control or can validate through third-party due diligence. (NIST SP 800-53 Rev. 5)

3) Validate “every boundary has a barrier”

Walk the site (or have facilities do a walkdown) and test:

• Doors fully close and latch
• Locks work and keys are controlled
• Hinges and frames are intact (no bypass gaps)
• Emergency exits have appropriate one-way egress and alarms where appropriate
• Server racks/cages are locked and keys/combos are controlled
• Temporary openings (construction, cabling) are sealed or compensating controls are documented (NIST SP 800-53 Rev. 5 OSCAL JSON)

Document failures as tickets and track to closure.

4) Tie barriers to access governance (so it’s operational, not one-time)

PE-3(7) does not stand alone. Make the barrier meaningful by connecting it to:

• Authorized roles (HR-driven joiner/mover/leaver)
• Visitor handling (escort rules for restricted zones)
• Key/badge issuance, retrieval, and periodic reconciliation
• Exception approvals (temporary access, broken door, construction) (NIST SP 800-53 Rev. 5)

You do not need to over-engineer the process, but you do need one that produces consistent evidence.

5) Establish inspections and maintenance as recurring work

Define:

• Who inspects barriers (facilities, security, or joint)
• What “pass/fail” means (door doesn’t latch = fail; cage lock missing = fail)
• How issues are prioritized and fixed (work orders, security tickets)
• How you review recurring issues (repeat “door propped open” events should trigger corrective action)

Assessors often accept reasonable operationalization if you can show a clean chain from inspection to remediation. (NIST SP 800-53 Rev. 5)

6) Third-party sites: bake barriers into due diligence

If a third party controls the premises:

• Contractually require physical barriers appropriate to the hosted assets (cages, controlled entry points).
• Obtain evidence: site security description, photos/diagrams if allowed, and audit reports provided by the third party.
• Document your review and any gaps plus remediation plan or risk acceptance. (NIST SP 800-53 Rev. 5)

If you use Daydream for third-party risk management, map PE-3(7) to the control owner, implementation procedure, and recurring evidence artifacts so your assessments produce the same artifacts every cycle without re-inventing the evidence list. (NIST SP 800-53 Rev. 5 OSCAL JSON)

Required evidence and artifacts to retain

Keep an “audit-ready” PE-3(7) packet with:

1. Physical security zoning list (restricted areas, purpose, asset classes).
2. Facility diagrams or annotated floor plans showing boundaries and controlled entry points.
3. Barrier inventory (doors, locks, cages, racks), owner, and location.
4. Inspection records (checklists, findings, dates, inspector).
5. Work orders/tickets for repairs and remediation, with closure proof.
6. Access governance artifacts tied to barriers (key/badge issuance records, retrieval on termination, visitor/escort logs as applicable).
7. Exceptions register (temporary barrier disablement, construction, emergency conditions) with approvals and compensating controls.
8. Third-party evidence for offsite locations (attestations, reports, or provider security documentation) plus your review notes. (NIST SP 800-53 Rev. 5)

Common exam/audit questions and hangups

Assessors and auditors usually press on these:

• “Show me your restricted areas.” They want a list plus a diagram, not a verbal description.
• “What stops someone from walking in?” Expect them to test doors, ask about propping, and look for bypass paths (shared ceilings, unlocked racks).
• “How do you know the barriers work today?” One-time installation proof is weak without inspections and work orders.
• “What about the colo?” If your system boundary includes hosted gear, they will ask for your evidence of the colo’s barriers and your own cage controls. (NIST SP 800-53 Rev. 5)

A frequent hangup: teams produce a strong policy but cannot produce repair tickets, inspection logs, or a current inventory of barriers. That reads as “designed but not operating.” (NIST SP 800-53 Rev. 5)

Frequent implementation mistakes (and how to avoid them)

1. Relying on badge readers without a door. If the opening is physically open, you did not build a barrier. Add a door, gate, or turnstile, or re-scope the restricted zone. (NIST SP 800-53 Rev. 5 OSCAL JSON)

2. No defined zone boundaries. “Server room” is not enough in mixed-use spaces. Define the boundary that actually separates the protected assets (cage line, locked rack row).

3. Propped doors become normal. Fix root causes: install auto-closers, adjust latches, add “no prop” signage, enforce through local leadership, and track repeat incidents through tickets.

4. Key control is informal. A locked door with uncontrolled master keys is a weak barrier in practice. Centralize issuance, require approvals, and document returns.

5. Construction and cabling changes punch holes in barriers. Require security review for facilities changes affecting restricted areas and document temporary compensating controls. (NIST SP 800-53 Rev. 5)

Enforcement context and risk implications

No public enforcement cases were provided for this requirement in the supplied sources, so this page does not cite enforcement actions. Operationally, weak physical barriers raise the likelihood of unauthorized physical access, which can bypass logical controls through device theft, rogue hardware insertion, or direct console access. Treat PE-3(7) as a prerequisite for credible system boundary claims under NIST SP 800-53. (NIST SP 800-53 Rev. 5)

Practical execution plan (30/60/90)

Use this as an operator’s cadence; adapt to your facility footprint and third-party dependencies.

First 30 days (stabilize and define)

• Name a control owner (security or facilities) and a backup.
• Publish the restricted zone list and get stakeholder sign-off (IT, facilities, security).
• Collect diagrams/floor plans and mark boundaries.
• Perform a walkdown and open remediation tickets for obvious gaps (doors, locks, racks).
• Stand up the PE-3(7) evidence folder structure and templates (inventory, inspections, exceptions). (NIST SP 800-53 Rev. 5 OSCAL JSON)

Days 31–60 (implement and evidence)

• Close priority remediation items; document before/after.
• Implement key/badge governance ties for restricted zones (approval path, retrieval process).
• Start recurring inspections and log results.
• For third-party sites, request physical security documentation and document your review. (NIST SP 800-53 Rev. 5)

Days 61–90 (operationalize and reduce audit friction)

• Run at least one full cycle of inspection → findings → repair → verification.
• Reconcile access lists/keys against authorized roles; clean up stale access.
• Formalize the exceptions register and require approvals for any barrier downtime.
• Load the control mapping (owner, procedure, recurring evidence artifacts) into your GRC system; Daydream is a practical place to keep third-party evidence and recurring artifact requests consistent across review cycles. (NIST SP 800-53 Rev. 5 OSCAL JSON)

Frequently Asked Questions

Does a security camera count as a physical barrier for PE-3(7)?

No. Cameras provide detection and deterrence, but the requirement calls for limiting access using physical barriers. Use cameras as a supporting control, not the primary means of restriction. (NIST SP 800-53 Rev. 5 OSCAL JSON)

If my office suite has a locked front door, is that enough?

Sometimes, but only if the locked door meaningfully restricts access to the specific protected assets. If sensitive systems are inside an open area past the suite door, you may still need internal doors, cages, or locked racks to create a true restricted zone. (NIST SP 800-53 Rev. 5)

We’re in a colocation data center. What barrier evidence should we keep?

Keep proof of your cage or cabinet locks and your access authorization records, plus the colo’s documentation describing controlled entry (for example, mantraps or guarded access) and your review notes. The goal is to show you validated the third party’s barriers and you control access to your footprint. (NIST SP 800-53 Rev. 5)

Are locked server racks acceptable if we can’t get a dedicated server room?

Yes, locked racks or cages are common compensating barrier patterns in shared spaces. Document why the room cannot be restricted and show that the rack/cage boundary prevents physical access to the equipment. (NIST SP 800-53 Rev. 5 OSCAL JSON)

How do we handle emergency exits without creating safety issues?

Keep life-safety egress compliant while controlling entry into restricted areas. Common patterns are one-way egress hardware and alarms on emergency exit doors; document the design and how you respond to alarms as part of your physical security operations. (NIST SP 800-53 Rev. 5)

What’s the fastest way to reduce audit friction for PE-3(7)?

Build a single evidence packet: zone definitions, diagrams, barrier inventory, inspection logs, and repair tickets. Then map the requirement to an owner and a recurring evidence schedule so you can reproduce the packet on demand, including for third-party sites tracked in Daydream. (NIST SP 800-53 Rev. 5 OSCAL JSON)