Information · Key to NFRC Codes
Key to NFRC Codes
Every product in the NFRC Certified Products Directory (CPD) is described by a short string of codes: what kind of product it is, what the frame and sash are made of, the thermal break, the gas fill, the glass tint, the spacer and any grids. This page explains each code so you can read a CPD listing, an NFRC label certificate or a simulation report.
The codes below follow NFRC's current code listing (January 2026). NFRC periodically retires and adds codes; older listings and reports may still show retired codes, such as PRFX, CSTH or the AL frame code, which are noted at the end of this page. You can search certified products at the NFRC Certified Products Directory.
How to read a listing
A typical CPD entry for a window lists the product type, then the frame and sash material, thermal break and, for each glazing option, the number of glass layers, the Low-E coatings, the gas fill in each cavity, the spacer, the tint and the grid. For example:
| Field | Code | Meaning |
|---|---|---|
| Product type | DATT | Dual action (tilt-turn) window |
| Frame / sash | FG / FG | Fiber-reinforced (fiberglass) frame and sash |
| Thermal break | NA | No separate thermal break needed |
| Gas fill | ARG | Argon |
| Spacer | ZF-D | Silicone foam spacer, dual seal |
| Tint | CL | Clear glass |
| Grid | N | No grids |
Example for illustration only; it is not a specific certified listing.
Product type codes
| Code | Product | Configuration |
|---|---|---|
| CSDV | Casement | Dual vent |
| CSSV | Casement | Single vent |
| PRAW | Projected | Awning |
| PVHR | Pivoted | Horizontal pivot |
| DATT | Dual action | Tilt-turn |
| VSSH | Vertical slider | Single hung |
| VSDH | Vertical slider | Double hung |
| HSOX | Horizontal slider | Single slider (one sash operates) |
| HSXX | Horizontal slider | Double slider (both sashes operate) |
| FIXD | Fixed | Picture window |
| FXSL | Fixed | Sidelite |
| FXTR | Fixed | Transom |
| GWGH | Garden window | Garden / greenhouse window |
| DDSG | Door | Sliding glass door, including lift-and-slide |
| EDSL | Door | Swinging entrance door, single |
| DDFR | Door | Swinging entrance door, double (French) |
| DASD | Door attachment | Dynamic attachment for swinging doors |
| VAGD | Door | Garage / rolling door |
| SKFX | Skylight | Fixed |
| SKOP | Skylight | Operable |
| SKDM | Skylight | Domed |
| TDDY | Skylight | Tubular daylighting device |
| SKSL | Sloped glazing | Sloped glazing system |
| GWCW | Glazed wall system | Curtain wall |
| GWWW | Glazed wall system | Window wall |
| GWSP | Glazed wall system | Spandrel panel system |
Frame and sash codes
The frame and sash are coded separately, for example FG/FG for a fiberglass frame and fiberglass sash.
| Code | Material | Description |
|---|---|---|
| AN | Aluminum | No thermally broken members (or not covered by another aluminum code) |
| AT | Aluminum | All members thermally broken |
| AU | Aluminum | All members thermally improved |
| AS | Aluminum | Extrusions reinforced with steel |
| AV | Aluminum / vinyl | Aluminum combined with vinyl or other plastic members, cladding, inserts or caps |
| SN | Steel | No thermally broken members |
| ST | Steel | All members thermally broken |
| SU | Steel | All members thermally improved |
| BN | Bronze | No thermally broken members |
| BT | Bronze | All members thermally broken |
| BU | Bronze | All members thermally improved |
| WD | Wood | All members solid wood |
| WM | Clad wood | Roll-formed metal cladding over wood |
| WA | Wood / metal | Wood members combined with metal extrusions |
| WV | Wood / vinyl | Vinyl or other plastic members or cladding combined with wood |
| WF | Wood / fiberglass | Fiberglass members combined with wood |
| WC | Wood / composite | Composite members combined with wood |
| VY | Vinyl | Vinyl or other plastic, no reinforcement |
| VR | Vinyl | Vinyl or other plastic, with reinforcement |
| VF | Vinyl | Vinyl or other plastic, foam-filled |
| VC | Vinyl | Cellular PVC |
| FG | Fiberglass | Fiber-reinforced members |
| FR | Fiberglass | Fiber-reinforced members with reinforcement |
| FF | Fiberglass | Fiber-reinforced members, foam-filled |
| CO | Composite | Vinyl composite or wood composite members |
| CR | Composite | Composite members with reinforcement |
| CF | Composite | Composite members, foam-filled |
| NF | No frame | Frameless systems, such as point-supported glass |
| NA | Not applicable | Sash code for products without a sash, such as fixed windows |
Thermal break codes
The material that separates the inside and outside of a metal frame. Fiberglass, wood and vinyl frames normally need no thermal break.
| Code | Material |
|---|---|
| NA | No thermal break |
| PN | Polyamide / reinforced nylon |
| UR | Urethane / polyurethane |
| FG | Fiberglass |
| FO | Foam |
| NE | Rigid neoprene / EPDM |
| VY | Vinyl or other plastic |
| AI | Air |
Gas fill codes
The gas in each space between panes. Vacuum insulating glass has its own codes.
| Code | Fill |
|---|---|
| AIR | Air |
| ARG | Argon / air |
| KRY | Krypton / air |
| AR3 | Argon / krypton / air mixture |
| XEN | Xenon / air |
| VIG | Vacuum insulating glass |
| VIC | Vacuum insulating glass, rated using NFRC's C* procedure |
Tint codes
The body tint of the glass. Low-E coatings are listed separately in the glazing description.
| Code | Tint |
|---|---|
| CL | Clear |
| GY | Gray |
| BZ | Bronze |
| GR | Green |
| BL | Blue |
| SR | Silver |
| GD | Gold |
| BK | Black |
| WH | White |
| RD | Red |
| OG | Orange |
| YL | Yellow |
| PR | Purple |
| SF | Suspended polyester film |
| NA | Not applicable (no glazing) |
Spacer codes
Each spacer code ends in -S (single seal) or -D (dual seal), for example ZF-D. A dual-seal unit has a primary seal, usually polyisobutylene, plus a secondary structural sealant, and generally offers better gas retention and durability.
| Code | Spacer |
|---|---|
| A1 | Aluminum |
| A2 | Thermally improved aluminum |
| A3 | Aluminum-reinforced polymer |
| A4 | Aluminum / wood composite |
| A5 | Aluminum-reinforced butyl |
| A6 | Aluminum / foam / aluminum |
| A7 | U-shaped aluminum embedded in sealant |
| A8 | Aluminum-butyl composite (exposed corrugated aluminum) |
| A9 | U-channel aluminum with thermal cap |
| CS | Coated steel |
| CU | U-shaped coated steel embedded in sealant |
| SS | Stainless steel |
| SU | U-shaped stainless steel embedded in sealant |
| S2 | Stainless steel with urethane thermal break |
| S3 | Steel / foam / steel |
| S5 | Stainless steel-reinforced butyl |
| S6 | U-channel steel with thermal cap |
| SP | Stainless steel / plastic substrate |
| SX | Thermally improved stainless steel, any shape (dual seal only) |
| TP | Thermoplastic |
| TS | Thermoplastic with stainless steel substrate |
| ZF | Silicone foam |
| ZE | Elastomeric silicone foam |
| ZS | Silicone foam combined with steel |
| PU | Polyurethane foam |
| OF | Organic foam |
| ER | EPDM-reinforced butyl |
| FG | Fiberglass |
| P2 | Polycarbonate-butyl composite (P1: earlier model, no new entries; P3: P1 with a 0.01 adder) |
| GL-S | Welded glass edge (single seal only) |
| WD-N | Wood spacer (no seal designation) |
| N | Not applicable |
Grid type codes
| Code | Grid type |
|---|---|
| (blank) | No grids |
| G | Grids between the glass |
| T | True divided lites |
Grid size codes
| Code | Grid size or style |
|---|---|
| (blank) | No grids |
| N | No grids |
| S | Simulated divided lites, without grid bars between the glass |
| W | Simulated divided lites, with grid bars between the glass |
| 0.75 | Grid bars less than 1 in wide |
| 1.5 | Grid bars 1 in wide or more |
Retired codes
These codes appear on older listings, reports and labels but are no longer used for new certifications.
| Category | Codes no longer used for new listings |
|---|---|
| Product types | CSOX, CSTH, CSUN, DAOT, FIGS, FIUN, FXEL, FXGS, FXHR, GWSL, HSUN, HTDD, OTBA, OTBO, PRFX, PROJ, PRUN, PVVT, SKUN, VSUN |
| Frame and sash | AL (now AN), AP, AI, AB, AW (now WM), CW, CP (now VC), PA, PC, PF, PH, PI, PL, PP, PV, PW, VA, VH, VI, VP, VV (now VR), VW, WP, OT |
| Thermal break | AB, F (now FO), FB (now FG), N (now NA), O, P and RN (now PN), U (now UR), V (now VY) |
| Gas fill | AR2, CO2, SF6, XE2, XE3, U, N |
| Tint | AZ, EV, OT, RC, RS, BG, RG, DV, DY |
Opaque doors and door components also use NFRC codes for door skin and core materials; see the full NFRC code listing. Source: NFRC Codes Listing, January 2026. See also NFRC & ENERGY STAR.