Trifab® 451UT

Thermal simulations showing temperature variations from exterior/cold side to interior/warm side.

Trifab® 451UT


Trifab® VG framing systems offer designers a choice of front-, center-, back- or multi-plane glass applications. Structural silicone glazing (SSG) and Weatherseal glazing options further expand the designers’ choices, allowing for a greater range of design possibilities for specific project requirements and architectural styles. All systems have a 4-1/2" frame depth – Trifab® VG 450 has 1-3/4" sightlines, while Trifab® VG 451/451T and Trifab® 451UT have 2" sightlines.

With seamless incorporation of Kawneer entrances or windows, including GLASSvent® visually frameless ventilators, Trifab® VG can be used on almost any project. These framing systems can also be packaged with Kawneer curtain walls and overhead glazing, thereby providing a full range of proven, and tested, quality products for the owner, architect and installer from a single source supplier.


Trifab® VG 450, 451 and 451T framing systems offer four fabrication choices to suit your project (Trifab® 451UT available as screw spline fabrication only):

  • Screw Spline – for economical continuous runs utilizing two piece vertical members that provide the option to pre-assemble units with controlled shop labor costs and smaller field crews for handling and installation.
  • Shear Block – for punched openings or continuous runs using tubular moldings with shear block clips that provide tight joints for transporting large pre-assembled multi-lite units.
  • Stick – for fast, easy field fabrication. Field measurements and material cuts can be done when metal is on the job.
  • Type B – Same fabrication benefits as shear block except head and sill run through.

All systems can be flush glazed from either the inside or outside. The Weatherseal option provides an alternative to SSG vertical mullions for Trifab® VG 450, 451 and 451T. This ABS/ASA rigid polymer extrusion allows complete inside glazing and creates a flush glass appearance on the building exterior without the added labor of scaffolding or swing stages. Additionally, High-Performance (HP) Flashing options are engineered to eliminate perimeter sill fasteners and associated blind seals.


Architectural Class I anodized aluminum finishes are available in clear and Permanodic® color choices.

Painted finishes, including fluoropolymer that meet or exceed AAMA 2605, are offered in many standard choices and an unlimited number of specially-designed colors.

Solvent-free powder coatings add the “green” element with high performance, durability and scratch resistance that meet the standards of AAMA 2604.


Kawneer’s Isolock® Thermal Break process creates a composite section, prevents dry shrinkage and is available on Trifab® VG 451T. For even greater thermal performance, a “dual” Isolock® Thermal Break is used on Trifab® 451UT.

U-factor, CRF values and STC ratings for Trifab® VGvary depending upon the glass plane application. Project specific U-factors can be determined for each individual project. (See the Kawneer Architectural Manual or for additional information).

Performance Test Standards

Air Performance ASTM E 283
Water AAMA 501 and ASTM E 331
Structural ASTM E 330
Thermal AAMA 1503
Thermal Break AAMA 505 and AAMA TIR-A8
Acoustical AAMA 1801 and ASTM E 1425

Trifab® VG 450, 451 and 451T glazing options
(note: Trifab® 451UT available as center set glass plane only).