Extended Plate & Beam Wall System
Published Thursday, March 15, 2018
Extended Plate and Beam (EP&B) is an advanced wall system developed by Home Innovation Research Labs (HI). The New York State Energy Research & Development Authority, Forest Products Labs and DOW Chemical have partnered with HI to test and optimize the system, and now bring you this guide with all the information you need to build a high-performing wall at reasonable cost and effort that meets or exceeds Energy Code prescriptive insulation requirements for all U.S. climate zones.
EP&B is based on tried-and-true lumber construction methodologies, integrating rigid foam sheathing with standard framing practices into a system that preserves many conventional construction features and minimizes builder risk. The EP&B wall system is composed of familiar wall materials but in a different configuration:
- 2x4 studs, with top and bottom plate extensions of 2x6
- 2-in. continuous insulation (c.i.) exterior to the wall cavity, interior to the wood structure panel (WSP)
- More than 95% of the wall area free of thermal bridging
- Common methods and materials for framing, air-sealing, insulation, drainage plane and siding attachment
- Double rim board (beam) that is also a header and is inset to provide space for a c.i. thermal break
The construction guide contains all the information you need to build a high-performing wall at reasonable cost and effort that meets or exceeds energy code prescriptive insulation requirements for all U.S. climate zones.
Introduction - Extended Plate & Beam Wall System
Basic Builder's Guide
Complete Construction Guide
System Development
Any large-scale builder transition to a higher performing wall system will require construction details and methods that are based on common and accepted industry practices. This is understood based on the minimal diffusion of alternative wall systems such as Structural Insulated Panels (SIPs) or Insulated Concrete Forms (ICF) wall technologies that have a long history in the building industry. The transition time for builders to make significant changes to construction practices is known to extend over decades. The EP&B wall system was developed as an opportunity to bridge this long transition timeframe by maintaining industry accepted construction practices while employing wall design features that increase the thermal performance of the wall by over 50%.
Initial Research Assessment
An Extended Plate and Beam (EP&B) demonstration home was built in Cazenovia, NY in 2015 using panelized wall sections produced at a nearby manufacturing plant. Positive results from the 2014/2015 evaluation as well as moisture monitoring of the EP&B wall done in a parallel study in partnership with the Forest Products Research Lab indicated that a test home project was an appropriate next step in the development of the EP&B system.
Demonstration Home
Home Innovation Research Labs studied the extended plate and beam (EP&B) wall system during a two-year period from mid-2015 to mid-2017 to determine the wall’s structural performance, moisture durability, constructability, and cost effectiveness for use as a high-R enclosure system for energy code minimum and above-code performance in climate zones 4–8.
This research was intended to explore the structural, thermal, and moisture performance of a wall that can be readily adopted by the large cohort of traditional builders who have previously resisted the switch to a high-R wall. Despite many years of development, structural insulated panels, insulated concrete forms, and double wall construction command a small market share of residential wall systems, which is largely because of atypical materials, methods, and details that require retooling and retraining. Use of 2x6 framing provides deeper stud cavities for more insulation, but the maximum thermal performance of the wall is effectively limited to 2015 International Energy Conservation Code (IECC) targets for climate zones 3–5, and the temperature profile across the wall subjects the cavity to moisture condensation risk in colder climates.
Full Field Research Report