Wall A/B/C, slab-to-slab construction, ceilings, floors, windows, utilities on perimeter walls, and vault construction under Tech Spec 3.C.5 and FED-STD 832.
The perimeter is the continuous envelope around the SCIF: every wall, the true floor, the true ceiling, every door and window, and every duct, pipe and conduit that passes through them. If any one of those elements is weaker than the rest, the perimeter is only as good as that element.
The governing definitions:
ICS 705-1 §G.1: "The perimeter of the SCIF includes all perimeter walls, windows and doors as well as the ceiling and floor" and "shall provide a physical barrier to forced, covert and surreptitious entry."
Tech Spec v1.5.1 §3.C.1: "SCIF perimeters include all walls that outline the SCIF confines, floors, ceilings, doors, windows and penetrations by ductwork, pipes, and conduit."
UFC 4-010-05 §3-3.2: the perimeter includes walls, ceiling, floor and all penetrations, and this "includes above the false ceilings and below raised floors."
ICS 705-1 §G.1: "Walls, floor and ceiling shall be permanently and solidly constructed and attached to each other," and construction shall "provide visual evidence of unauthorized penetration."
A compliant perimeter does four jobs at once:
Job
Driven by
Resist forced, covert and surreptitious entry
ICS 705-1 §G.1; Tech Spec 3.C
Show visual evidence of any penetration
ICS 705-1 §G.1; wall finish rules
Keep conversations from being understood outside
Sound Group 3 or 4 (Tech Spec Ch. 9)
Provide TEMPEST/RF protection
Only when the CTTA recommends it (Tech Spec 3.C.4)
These two ideas are often confused. They drive different construction details, and an inspector checks for both.
Concept
What it means in practice
Where it shows up
Visual evidence of surreptitious (covert) penetration
The perimeter must be built so any hole, cut, removed panel or re-finished patch is noticeable on inspection. Walls are hard-finished and painted slab to slab, penetrations are sealed and finished, and above-ceiling perimeter surfaces must be inspectable. This is about detection, not stopping an attacker.
ICS 705-1 §G.1; Tech Spec Wall A notes; UFC 3-4.5
Physical (forced-entry) protection
The perimeter must delay an intruder long enough for the IDS and response force to act. The Tech Spec gets this from enhanced walls (expanded metal or plywood), vault construction, steel bars or grilles in ducts, and hardened doors and hardware.
Conversations inside cannot be understood outside.
ICS 705-1 §G.1.a.5; Tech Spec Ch. 9
TEMPEST/RF protection
Applied only when the Certified TEMPEST Technical Authority (CTTA) recommends it.
Tech Spec 3.C.4; ICS 705-1
UFC 4-010-05 §3-4.5 ties them together: ceilings and floors must meet "same requirements as walls with regard to forced entry, covert entry, visual evidence of surreptitious penetration, and sound attenuation."
Every SCIF perimeter wall runs from the structural floor slab to the underside of the structural deck above. A wall that stops at a suspended ceiling is not a perimeter wall.
The requirement appears in two places:
Tech Spec wall figures: the "entire wall assembly shall be finished and painted from true floor to true ceiling."
UFC 4-010-05 §3-4.4: "Walls must go from floor slab (true floor) to underside of floor or roof deck (true ceiling)."
What that means at the top and bottom of the wall:
Track: 16-gauge continuous top and bottom track with anchors at 32 in. on center maximum, bedded in a continuous bead of acoustical sealant (Tech Spec Wall A).
Sealant: the top and bottom of each wall are sealed with acoustic sealant where the wall meets the slab.
Voids: remaining voids are filled with fire-safe grout or acoustic sealant.
Finish: the full height, including the portion above any drop ceiling, is finished and painted.
UFC 4-010-05 §4-7 calls for a photographic construction surveillance record documenting construction at critical areas, including wall assemblies and perimeter penetrations. Top-of-wall conditions are exactly what an inspector cannot see once the ceiling grid and board are installed.
Tech Spec §3.C and Figures 1–3 define three perimeter wall types. All three share the same framing, track, acoustic fill and finish rules. B and C add a hardening layer for forced-entry delay.
Element
Wall A: Standard
Wall B: Enhanced (expanded metal)
Wall C: Enhanced (plywood)
Gypsum wallboard
Three layers 5/8 in. GWB: one on the uncontrolled side, two on the controlled side
Same as Wall A
Three layers 5/8 in. GWB: two on the uncontrolled side, one over minimum 1/2 in. plywood on the controlled side
Studs
3-5/8 in. 16-gauge metal studs or wood 2x4 studs (see note)
Same as Wall A
16-gauge studs
Track
16-gauge continuous top and bottom, anchors 32 in. o.c. max, bedded in acoustical sealant
Same
Same
Hardening layer
None
3/4 in. mesh, #9 (10-gauge) expanded metal on the interior side of all perimeter studs, spot-welded every 6 in. along each stud and at ceiling and floor; hardened screws with 1 in. washers or hardened clips may replace welding
1/2 in. plywood, 8 ft vertical by 4 ft horizontal, fastened to studs with glue and #10 steel tapping screws at 12 in. o.c.
Acoustic fill
3-1/2 in. sound attenuation material, fastened to prevent sliding
Same
Same
Joints
Interior layers staggered so seams do not align; top and bottom sealed
Wall selection follows the SCIF's operating mode and whether the AO accepts Security-in-Depth (SID). Tech Spec §3.C.2–3.C.3 assigns the wall types; §3.H sets the matching alarm response times for U.S. facilities.
SCIF profile (inside the U.S.)
Perimeter wall
Initial alarm response (Tech Spec 3.H)
Closed storage (all SCI in GSA-approved containers)
Wall A
15 minutes
Secure Working Area (no SCI storage)
Wall A
15 minutes
Continuous operation (staffed 24/7)
Wall A
Not separately stated in 3.H
Open storage with AO-accepted SID
Wall A
15 minutes
Open storage without SID
Wall B or Wall C
5 minutes
How SID enters the decision:
Tech Spec 2.B.1: SID "describes the factors that enhance the probability of detection before actual penetration to the SCIF occurs," and SID "may alter construction requirements with AO approval."
SID is documented, not assumed. The Fixed Facility Checklist has a Security-in-Depth section, and the Construction Security Plan template has a SID documentation block.
Tech Spec 2.B.2: SID is mandatory for SCIFs outside the U.S.
Not every perimeter is new stud framing. Three situations come up on most tenant improvements.
Existing substantial walls.
Tech Spec §3.C.1: "When an existing wall is constructed with substantial material (e.g., brick, concrete, cinderblock, etc.) equal to meet the perimeter wall construction standards, the existing wall may be utilized," pending AO approval. UFC 4-010-05 §3-4.4 repeats this for brick, concrete and masonry. The wall still has to be slab to slab, finished, and acoustically adequate, and every existing penetration through it has to be found and treated.
Fire-retardant plywood and building code.
UFC 4-010-05 §3-4.1: plywood "must be Fire Retardant Treated (FRT) in buildings required to be of noncombustible construction."
UFC also tells designers to "ensure that details used from IC Tech Spec … comply with UFC 1-200-01," the DoD building code.
The Tech Spec wall figures are security details, not listed fire-rated assemblies. Where a perimeter wall is also a rated wall, the designer must reconcile both.
Walls for Sound Group 4.
UFC 4-010-05 §3-4.4.2 notes that the standard STC 45 wall has three layers of 5/8 in. GWB and associates STC 50 with four layers (two on each side).
UFC §3-4.4.3 allows "one layer of factory laminated GWB meeting ASTM C1766" to enhance attenuation.
RF shielding is a CTTA-driven countermeasure. It is not a default ICD 705 requirement.
The public requirements:
Tech Spec §3.C.4: "RF protection shall be installed at the direction of the CTTA when a SCIF utilizes electronic processing and does not provide adequate RF attenuation at the inspectable space boundary." Installation follows "either the drawings or Best Practices Guidelines for Architectural Radio Frequency Shielding."
Tech Spec wall construction (3.C.3): CTTA-recommended countermeasures may include foil-backed gypsum wallboard or a layer of approved radiant-barrier foil, installed per the RF best-practices guidelines.
ICS 705-1 §G.1.a(4): "When RF shielding is required by Certified TEMPEST Technical Authority (CTTA) evaluation, it should be planned for installation during initial construction."
Tech Spec §3.G.5: utility distribution on the interior of a perimeter wall treated for acoustics or RF must be surface mounted, in a raceway, or behind an additional wall, so the treatment is not penetrated.
UFC 4-010-05: the TEMPEST Addendum is submitted during planning so the CTTA can produce a TEMPEST Countermeasures Review (TCR).
What this means for the build team:
Do not self-specify shielding or claim a room is "TEMPEST compliant." The CTTA's documented recommendations govern.
Get the TCR before walls are detailed, because shielding changes wall sequencing, door selection and every penetration.
Protect installed shielding from later trades. Screws, back boxes and cable holes through foil defeat it.
The true ceiling and true floor are perimeter surfaces. They are held to the same standard as the walls.
Tech Spec §3.D: "Floors and ceilings shall be constructed to meet the same standards for force protection and acoustic protection as walls." "All floor and ceiling penetrations shall be kept to a minimum."
UFC 4-010-05 §3-4.5: ceilings and floors must meet the same requirements as walls for forced entry, covert entry, visual evidence of surreptitious penetration, and sound attenuation.
Practical implications:
Condition
Question to answer early
Concrete slab above and below
Are there existing core drills, abandoned sleeves, or floor boxes that open to the floor below?
Metal deck with concrete topping
Are deck flutes at the wall line infilled and sealed?
Roof deck (top floor)
Are roof drains, curbs, or rooftop equipment supports penetrating the SCIF area?
Floor above or below is another tenant
Are there plumbing, conduit or duct penetrations through the slab serving that tenant? (Tech Spec 3.G.3 bars utilities for other areas from transiting the SCIF unless mitigated with AO approval.)
The Fixed Facility Checklist asks separately for the true ceiling (material and thickness), false ceiling, true floor (material and thickness), and false floor. Answer those from as-built conditions, not from the base-building drawings.
A drop ceiling or raised access floor is a finish, not the perimeter. The perimeter is the true slab and deck. The space above a drop ceiling and below a raised floor is inside the perimeter analysis (UFC 4-010-05 §3-3.2).
Inspectability.
UFC 4-010-05 §3-4.1.1: "The design should facilitate future inspections by minimizing the above ceiling obstructions on the controlled and uncontrolled side of the secure perimeter." Coordinate above-ceiling inspection methods with the SSM or SSO. That affects:
Ceiling grid layout (removable tiles along the perimeter wall line).
Duct, cable tray and sprinkler routing that could hide the top of the wall.
Access to duct bars and inspection ports.
UFC §3-4.2 also warns that acoustic Z-ducts "can increase the above ceiling space requirement." Check plenum depth before committing to a space.
Motion sensors above ceilings and below floors.
UFC 4-010-05 §3-4.17.3: motion sensors are "not normally required above false ceilings or below false floors; however, these detectors may be required by the AO for critical and high threat facilities outside the U.S."
Tech Spec 7.A.3.a(5): motion above false ceilings or below false floors may be required at overseas Category I and II locations.
Anything recessed into a perimeter wall cuts through the acoustic and physical layers. The rules push utilities onto the surface or onto a separate furred wall.
Rule
Source
On perimeter walls treated for acoustics or RF, interior distribution must be "surface mounted, contained in a raceway, or an additional wall"
Tech Spec §3.G.5
"Do not mount utilities in a manner that will affect the acoustic or RF shielding performance"; use surface mounting or a furred-out wall faced with gypsum board
UFC 4-010-05 §3-4.4.7
"Recessed fire extinguisher cabinets are prohibited on perimeter or sound rated compartmented area walls"
UFC 4-010-05 §3-4.4.8
Recessed PED (portable electronic device) cabinets are prohibited on perimeter walls; PED cabinets cannot be within 10 ft of equipment processing unencrypted national security information
UFC 4-010-05 §3-4.7
Spare conduit through the perimeter must be filled with acoustic fill and capped
Tech Spec §3.G.6
Surface mount vs. furring:
The Tech Spec permits either.
One end-user practitioner recommends surface mount because a furred wall makes the true perimeter harder to inspect. Some AOs share that preference.
Windows are the weakest part of most perimeters for forced entry, visual observation and sound. The Tech Spec starts from "avoid them."
Requirement
Source and wording
Minimize
"Every effort should be made to minimize or eliminate windows in the SCIF, especially on the ground floor." (Tech Spec §3.F.1)
Non-opening
"Windows shall be non-opening." (§3.F.2)
Visual and acoustic protection
Windows shall "provide visual and acoustic protection." (§3.F.2)
RF
"Windows shall be treated to provide RF protection when recommended by the CTTA." (§3.F.4)
Visual protection methods (DoD)
"full surface acid etching, sand blasting, or an obscure polyvinyl butyral interlayer" with "maximum of 75% diffuse transmittance and a minimum haze of 90%" per ASTM D1003 (UFC 4-010-05 §3-4.10)
The Fixed Facility Checklist asks three window questions: Are they acoustically protected? Are they secured against forced entry? Are they protected against visual surveillance?
Visual protection covers more than people walking by. It includes observation of screens, whiteboards and keypads from neighboring buildings.
Height above grade changes what a window must do. Low windows are treated as part of the physical perimeter and must be alarmed.
Window location
Requirement
Source
Within 18 ft of the ground or an accessible platform
Must have "protection against forced entry" and "meet the standard for the perimeter"
Tech Spec §3.F.3
Within 18 ft of the ground or an accessible platform
Must be "protected by security alarms in accordance with Chapter 7"
Tech Spec §3.F.5
Less than 18 ft (5.5 m) (DoD)
Must meet perimeter standards and be monitored by IDS
UFC 4-010-05 §3-4.8.1
Any height
Non-opening; visual and acoustic protection; RF treatment if the CTTA recommends
Tech Spec §3.F.2, 3.F.4
Skylights and clerestories.
UFC 4-010-05 §3-4.9 applies the same logic to daylighting elements: non-opening, visual and acoustic protection, TEMPEST countermeasures when recommended by the TEMPEST Countermeasures Review, and, below 18 ft, perimeter-standard construction with IDS monitoring.
Applying the rule.
Measure from the ground and from any accessible platform. A second-floor window can fall inside the rule.
A window inside the 18-ft zone needs a forced-entry solution equivalent to the adjacent wall and an IDS sensor.
A window above 18 ft still needs non-opening, visual, acoustic and (if directed) RF treatment.
Most U.S. commercial SCIFs never build a vault. They use Wall A with IDS and GSA-approved containers (closed storage), or enhanced walls for open storage without SID. A vault is a deliberate choice for higher-risk storage.
What the public texts say:
Tech Spec §3.C.5, "Vault Construction Criteria," sits under the perimeter wall criteria and is written as an option: "GSA-approved modular vaults meeting Federal Specification AA-V-2737 or one of the following construction methods may be used."
The Tech Spec chapters reviewed do not set a blanket rule that requires a vault for a U.S. SCIF.
32 CFR 2001.43 and 32 CFR 117.15(c) describe vaults as storage built to Federal Standard 832 for collateral classified storage.
Tech Spec §3.I: when a Secure Working Area is unoccupied, SCI is stored in GSA-approved containers within a SCIF, in a vault, or destroyed.
Typical drivers for vault construction:
Driver
Why it points to a vault
Large volumes of open-stored material
Container storage becomes impractical
Agency or program requirement
Some sponsors specify vault storage
Overseas threat Category
Higher threat drives more physical delay
AO risk management decision (Tech Spec Ch. 2)
Site-specific threat or response limitations
Two door rules follow a vault everywhere:
Tech Spec §3.E.6: a vault door cannot serve as day-access control. A vestibule with an access control device may be constructed in front of it.
UFC 4-010-05 §3-4.6.11: specify a "GSA-approved Class 5 vault door equipped to meet Architectural Barriers Act (ABA) Standards."
Tech Spec §3.C.5 offers three construction methods. All three require a GSA-approved Class 5 vault door.
Method
Tech Spec requirement (as extracted)
Modular vault
GSA-approved modular vault meeting Federal Specification AA-V-2737
Reinforced concrete
"a minimum thickness of eight inches of reinforced concrete"
Compressive strength "of at least 2,500 pounds per square inch (psi)"
"steel reinforcing rods, a minimum of 5/8 inches in diameter, positioned centralized in the concrete pour and spaced horizontally and vertically six inches on center"
Walls "anchored into the ceiling and floor to a minimum depth of one-half the thickness of the adjoining member"
Steel-lined
"1/4 inch-thick steel alloy-type plates having characteristics of high-yield and high-tensile strength"
Plates "continuously welded to load-bearing steel members of a thickness equal to that of the plates"
"firmly affixed to a depth of one-half the thickness of the floor and ceiling"
Door (all methods)
"All vaults shall be equipped with a GSA-approved Class 5 vault door"
What the build team has to coordinate:
Structure. An 8-inch reinforced concrete room is a structural element. Floor loading, embedment into slabs, and rebar placement need a structural engineer.
Vault door procurement. A GSA-approved vault door is a specialized procurement item. Confirm the door class and opening size with the AO before the rough opening is formed or poured.
Penetrations. Every penetration through a vault wall still follows the perimeter penetration rules for bars, grilles, acoustic treatment and CTTA-directed countermeasures.
Accessibility. Specify the vault door equipped to meet ABA standards (UFC 4-010-05 §3-4.6.11).
Day access. Plan a vestibule or separate day-access door. The vault door cannot serve as day-access control (Tech Spec §3.E.6).
Federal Standard 832, Construction Methods and Materials for Vaults (GSA, 1 Sep 2002), defines three vault classes. It is the standard usually referenced for collateral classified vaults. The Tech Spec uses similar but not identical numbers.
FED-STD 832 class
Protection statement
Construction (as extracted)
Door
Class A
"offer the maximum protection against tool and torch attack"
Walls, floor and ceiling of 8 in. reinforced concrete; 5/8 in. rebar, 6 in. on center each way, staggered each frame; concrete minimum 28-day compressive strength of 3,000 psi; monolithic reinforced concrete ceiling
AA-D-600 Class 5 vault door
Class B
"offer less than maximum protection"
Conforms to AA-V-2737 (modular vault)
Class 5 vault door
Class C
Less than maximum; for "unique structural circumstances" that do not permit concrete
Steel-lined with 3/8 in. steel alloy continuously welded to load-bearing steel members; where concrete floor or ceiling is less than 6 in., the steel liner is built the same as the walls
Class 5 vault door
FED-STD 832 also covers openings: those exceeding 96 square inches and over 6 in. in the smallest dimension require 9-gauge expanded metal mesh or rigid steel bars at least 1/2 in. in diameter, welded 6 in. on center.
