Elevating Thermal Performance in Below-Grade Construction

Energy-efficient homes are built from the ground up. In the pursuit of building excellence, optimal thermal performance stands paramount—especially in below-grade environments, which are prone to temperature fluctuations and moisture-related concerns. With builders now focusing on more than just aesthetics—considering factors such as energy efficiency and cost-effectiveness—understanding the appropriate products and techniques becomes imperative, aligning with the industry's move towards net-zero mandates. 

Here, we’ll explore strategies that enhance both thermal efficiency and moisture management—a dual approach that promises long-lasting, energy-efficient foundations.

Integrating Control Layers and Embracing Sustainability

Control layers form the foundation of a building's efficiency, minimizing heat transfer and maximizing energy conservation. Integrating air barriers, thermal insulation, and water-resistant barriers creates a comprehensive system control layer design. Meticulously selecting high-performance insulation materials, like DuPont™ Styrofoam™ Brand XPS continuous insulation (ci) enables builders to create a robust thermal envelope that resists thermal bridging and mitigates condensation potential, enabling a stable indoor climate year-round.

The industry’s transformative shift towards sustainability aligns with DuPont's commitment to eco-conscious practices. With a growing awareness of environmental impact, builders leverage innovative materials like low GWP Styrofoam™ Brand ST-100 XPS insulation for a greener future.

Continuous Insulation for a Sustainable Approach

In below-grade construction, where foundations directly contact the ground, maintaining stable indoor climates is vital. Such constructions commonly encounter thermal bridging issues, leading to inefficiencies in maintaining ideal temperatures. Styrofoam™ Brand XPS insulation products offer a crucial solution to minimize heat transfer through foundation walls.

This intervention significantly enhances overall thermal efficiency, a critical step in minimizing energy consumption and fostering a sustainable, environmentally conscious construction approach, considering that buildings account for approximately 40 percent of our energy use.

Harmonizing Components for Optimal Results

Achieving peak performance requires a synergistic approach, which is why DuPont Performance Building Solutions provides durable, innovative solutions for the whole house, including improving the thermal performance of residential foundations and slabs. These products are designed to work in harmony, combining Styrofoam™ insulation below-grade, with industry-leading solutions like DuPont™ Tyvek®  water-resistive barriers to fortify the envelope against water and air above-grade. Additionally, sealing and flashing above-grade wall penetrations with products such as DuPont™ FlexWrap™ EZ, provides an extra layer of defense against potential water intrusion, reinforcing building resilience and longevity.

Practical Strategies for Residential Applications

1. Exterior insulation for thermal performance: Apply DuPont™ Styrofoam™ Brand XPS insulation on foundation walls' exteriors to create a thermal barrier, significantly reducing heat loss and minimizing condensation risk, acting as a moisture deterrent.

2. Interior insulation as a complementary strategy: Insulate the interior side of foundation walls, complementing exterior insulation for a comprehensive thermal envelope. Styrofoam™ insulation offers customizable options, addressing energy efficiency and mitigating condensation potential in residential buildings.

Elevating thermal performance in below-grade construction is crucial for a resilient, energy-efficient foundation. Highlighting industry-leading insulation materials and strategic approaches underscores their pivotal roles in achieving superior thermal performance and moisture resistance. By adopting these strategies and utilizing recommended products, builders can confidently embark on below-grade projects, prioritizing energy efficiency and quality. 

For more information, check out the webinar “Below Grade Foundations: How to Do It Right the First Time & Why.” This webinar also offers attendees the opportunity to claim 1 AIA Learning Unit (1 LU).