Curtain Wall
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, we serve as the single-source leader in our industry. We partner directly with glaziers, contractors, architects, and building owners to solve complex design challenges. With innovative products, specialized design services, and integrated tools, we simplify construction processes and optimize performance for both interior and exterior applications—from sophisticated curtain walls to custom shower enclosures.
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 Apogee Architectural Metals. 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 | Forced Entry | Notes | ||||
| 0.30 | 0.24 | 0.20 | 0.12 | 0.075 | |||||||
| Reliance TC | 6" - 7 1/2" | 2 1/2" | - | 0.30 | - | NA | 0.19 | No | No | No | |
| Reliance HTC | 7 1/4" - 10 1/4" | 2 1/2" | NA | NA | NA | 0.20 | NA | No | No | No | |
| Reliance StormMax | 7 1/2" | 2 1/2" | - | 0.30 | - | NA | 0.19 | Yes | No | Yes | |
| ZS-HT | 3 3/4" | 2" | 0.45 | 0.42 | 0.38 | NA | - | No | No | No | Project-out vent |
* Based on NFRC 100 gateway size and configuration (78 3/4" x 78 3/4" fixed) 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 curtain wall assemblies shall be a maximum of 0.06 CFM/FT2 per NFRC 400 or ASTM E 283 at 1.57 psf (75Pa).
Code Requirements: (per IBC 2021 Section 1604.3.7)
The deflection of fenestration framing supporting glass subjected to 0.6 times the Component and Cladding design pressures shall not exceed the noted deflection based on the following length of span of the framing member:
13'-6" or Less = L/175
>13'-6" = L/240 + 1/4"
Additional Resources:
Whole Building Design Guide - Curtain Wall
National Fenestration Rating Council