9:00 am - 10:00 am | Room: Owens Corning Room | Session Chair: Bomani Khemet

Evaluating Building Air Tightness

Air Leakage Performance Of A Silicone-Based Air Barrier System

Air barrier systems (ABS) are essential elements in the performance of building envelopes and they are specified in the National Building Code of Canada (NBC) to minimize the infiltration and exfiltration of air through the building envelope to control the risk of condensation. Although their primary function is to control the movement of air across the building envelope, when placed on the exterior side of the wall assembly, the barrier may also function as a water resistive membrane, thereby reducing the movement of moisture towards the inside of the assembly.
 
This research work is focused on air leakage performance of a liquid-applied silicone-based ABS. The ABS included an air-barrier membrane applied to the field of the wall, a liquid-flashing applied to concrete elements, window openings, corners and gaps, an elastomeric sealant for joints, and a prefabricated transition membrane to bridge different wall elements and large joints. This ABS was intended for application in commercial steel-frame construction.

We first report on the testing of the standalone membrane on the basis of ASTM E2178 for air permeance. The standard method requires some modification to allow for the testing of elastomeric silicone membranes. We also report on the air-leakage testing for the entire silicone system as per ASTM E1424, which requires testing at both 20 °C and −20 °C on three walls: Wall-1 had no penetrations, Wall-2 had a window and 12 penetrations, and Wall-3 had a junction with a concrete floor and 27 penetrations. 

For acceptable performance, the NBC requires an ABS air leakage rate below 0.2 L/s.m2 before and after wind aging, at both 20 °C and −20 °C. The air leakage test results showed that the air leakage rate of silicone ABS can be well below 0.2 L/s.m2, and at least an order of magnitude better. In this paper we describe the test methods and troubleshooting necessary to characterize the materials in accordance with the standard methods.

Itzel Lopez-Carreon, National Research Council Canada

Ms. Lopez-Carreon has a BSc in Chemistry from University of Ottawa and is a technical officer with the Construction Research Centre at the National Research Council of Canada (NRC).

Her works at NRC relate to the development of sustainable polymer-based building envelope materials, their performance evaluation, aging and durability assessment. Her work entails physical and chemical analysis of polymeric materials aged under various oxidative, non-oxidative, and alkaline conditions. The primary characterization techniques she employs for materials analysis are dynamic mechanical analysis (DMA), Fourier-transform infrared spectroscopy (FT-IR), and solid-state nuclear magnetic resonance (NMR) spectroscopy.

Currently, she is leading a multi-year research project on outdoor weathering of silicone and polyurethane construction sealants in order to investigate their natural aging, compare it with laboratory accelerated aging and validate  a previously-developed crack growth model.