Windows
Oldcastle BuildingEnvelope® is North America's leading vertically integrated manufacturer, fabricator, and distributor of architectural glass, glazing systems, and hardware and supplies. With over 80 locations across the U.S. and Canada, OBE serves as the single-source leader in our industry. OBE partners directly with glaziers, contractors, architects, and building owners to solve complex design challenges. With innovative products, specialized design services, and integrated tools, OBE simplifies construction processes and optimize performance for both interior and exterior applications—from sophisticated curtain walls to custom shower enclosures.
Graham Architectural Products provides custom-engineered windows, doors, and window wall systems for complex architectural applications. With decades of experience, Graham delivers durable, attractive, and energy-efficient solutions for historic renovations and new construction—including hurricane-, blast-, and impact-resistant systems.
Product Recommendations
Developed to be IBC 2021 & IECC 2021 Compliant for Climate Zones 5 & 6 and MA Stretch Energy Code
The following product recommendations have been developed to assist owners, architects and contractors in the selection and specification of Apogee Architectural Metals commercial fenestration solutions that meet the requirements of the IBC 2021, IECC 2021 for the Northeast (i.e., Climate Zones 5 & 6) and MA Stretch Energy Code. Appropriate use and application of these recommendations will vary based on performance considerations and environmental conditions unique to each project and, therefore, do not represent the final opinion or recommendation of PACE Representatives or Oldcastle BuildingEnvelope or Graham Architectural Products. Contact PACE Representatives to develop a custom fenestration basis of design (BOD) package to meet your project specific performance requirements and design conditions.
| Series | Depth | Sightline | Thermal Performance* (center of glass U-Factor) | Impact | Ballistic | Blast | Notes | ||||
| 0.30 | 0.24 | 0.20 | 0.12 | 0.10 | |||||||
| Fixed | |||||||||||
| GT6800 | 3 3/8" | 2 1/8" | 0.35 | 0.30 | 0.26 | 0.23 | - | No | No | No | |
| SR6700 | 3 1/4" | 1 9/16" | 0.36 | 0.33 | 0.28 | - | - | No | No | No | Historic Steel Replica |
| HIGT6700 | 3" | 1 5/8" | 0.38 | 0.36 | 0.32 | - | - | No | No | No | |
| Projected | |||||||||||
| GT6800 | 3 3/8" | 3 5/16" | 0.42 | 0.39 | 0.36 | 0.30 | - | No | No | No | |
| GX6800 | 3 9/16" | 3 5/16" | - | 0.36 | 0.33 | 0.27 | - | No | No | No | |
| SR6700 | 3 1/4" | 2 1/16" | 0.50 | 0.47 | 0.43 | - | - | No | No | No | Historic Steel Replica |
| HIGT6700 | 3" | 1 5/8" | 0.44 | 0.42 | 0.38 | - | - | Yes | No | No | |
| ZS-HT | 3 3/4" | 2" | 0.45 | 0.42 | 0.38 | - | - | No | No | No | |
| Hung | |||||||||||
| GT2200 | 4" | 3 5/16" | - | 0.39 | 0.36 | - | - | No | No | No | Double Hung |
| HIGT2200 | 4" | 3 5/16" | - | 0.39 | 0.36 | - | - | Yes | No | No | Single Hung |
* Based on NFRC 100 gateway size and configuration for operation shown. Center of Glass (COG) Summary: | |||||||||||
Industry Insights
Code Requirements: (per IECC 2021 & MA Stretch Energy Code)
The prescriptive thermal performance requirements (i.e., U-Factor) for vertical fenestration systems are indicated in Table C402.4 of the IECC 2021. Frame material is no longer taken into account and the requirement is based on your climate zone and fenestration type. (e.g., Fixed, Operable or Entrance Doors)
| Climate Zone | 5 and Marine 4 | 6 | MA Stretch Code |
| Vertical Fenestration | |||
| U-Factor | |||
| Fixed Fenestration | 0.36 | 0.34 | 0.30 |
| Operable Fenestration | 0.45 | 0.42 | 0.32 |
| Glazed Wall System | NA | NA | 0.25 |
Prescriptive compliance is only allowed with a vertical fenestration area less than or equal to 30% of the gross above-grade wall area. Prescriptive compliance is allowed up to not more than 40% of the gross above-grade wall area if certain minimum floor areas are in the daylight zone and daylight responsive controls are incorporated.
U-Factors of fenestration systems (e.g., windows) shall be determined by an accredited, independant laboratory in accordance with either NFRC 100 or ANSI/DASMA 105 AND labeled by the manufacturer. Products lacking a U-Factor label shall be assigned a default U-Factor per IECC 2021 Tables C303.1.3(1)-(3).
The air leakage of window assemblies shall be a maximum of 0.20 CFM/FT2 per AAMA/WDMA/CSA101/I.S.2/A440 or NFRC 400. The maximum rate of 0.30 CFM/FT2 shall be permitted when tested in accordance with AAMA/WDMA/CSA101/I.S.2/A440 at 6.24 psf (300Pa).
Additional Resources:
Whole Building Design Guide - Windows
National Fenestration Rating Council