Evaluation of Air Leakage Properties of Seam-Fastened Mechanically Attached Single-Ply and Polymer-Modified Bitumen Roof Membrane Assemblies

Abstract

The National Research Council of Canada (NRCC) in collaboration with the Canadian Roofing Contractors Association (CRCA), National Roofing Contractors Association (NRCA), Roofing Industry Alliance for Progress, and the Single-Ply Roofing Institute (SPRI) addressed the issue of air movement in roof assemblies through a research and development project designated air movement impacts on roof Systems (AIR). The AIR steering committee developed goals for a two-phase testing program: Phase 1, quantify air permeances of single-ply and polymer-modified bitumen membrane materials; and Phase 2, quantify air leakage rates of seam-fastened mechanically attached single-ply and polymer-modified bitumen roof membrane assemblies. In Phase 1, four roof membrane materials were tested using ASTM E2178 test protocol to measure the air permeability rates. The tested materials meet the air permeability criterion of ASHRAE 189.1, ASHRAE 90.1, and the International Energy Conservation Code (IECC) for effective air barrier materials. In Phase 2, a test method for measuring air leakage rates across membrane roof assemblies was developed. Test assemblies were constructed with seam-fastened mechanically attached Phase 1 roof membrane materials, rigid board roof insulation, and steel roof decks. Each test assembly also included five common roof penetrations flashed in accordance with the manufacturers' installation instructions. The results demonstrated that the tested assemblies comply with ASHRAE 189.1, ASHRAE 90.1, and the IECC air leakage requirement for effective air barrier assemblies. An ASTM work item under the D08 committee is underway on the developed test method for measuring air leakage rates across membrane roof assemblies.

Eliminating Fastener Thermal Bridging in Low Slope Roofs: Energy Efficiency Savings versus Installation Costs

“…However, there are other benefits to adhered systems, including the following:  Adhered systems do not flutter or billow during high wind events, thereby eliminating the drawing up of interior conditioned air up into the roof assembly (e.g., infiltration). This latter phenomenon would naturally further reduce energy efficiency (see Pallin, Kehrer, and Desjarlais [19] and Molleti et al [20] for examples).…”

Optimizing Single-Ply Low-Slope Roofing Assemblies for Insulation Value

“…This latter phenomenon would naturally further reduce energy efficiency (see Molleti et al [23] for example). Also, fully adhered systems such as described by Case IV have higher wind uplift strengths.…”