What is High-Performance Building and How Does it Affect My Project?
High-performance building involves constructing homes that prioritize energy efficiency, indoor air quality, moisture management, durability, and overall comfort, often exceeding standard code requirements. It focuses on creating well-insulated, airtight structures with proper ventilation, effective HVAC systems, and sustainable materials that minimize energy consumption, reduce environmental impact, and enhance occupant well-being. In addition, high-performance homes are designed for resilience, with moisture control measures, durable finishes, and systems that optimize the building’s long-term performance. Contractors, however, sometimes cut corners on these factors to save costs, potentially compromising the home's energy efficiency, comfort, longevity, and overall health of its occupants.
1. Moisture Management and Control
Skipping Proper Flashing and Sealants
Contractors often neglect the importance of high-quality flashing around windows and doors to prevent water infiltration. When flashing is installed incorrectly or omitted, water can penetrate the building envelope, leading to rot, mold, and eventual structural damage, especially in humid environments like the Southeast.
Best Practice: Install durable flashing materials such as Huber’s “Zip Systems” advanced acrylic flashing tape and ensure correct installation, ensuring that flashing overlaps and directs water away from vulnerable areas.
Improper Moisture Barrier Installation
Vapor barriers are essential in managing moisture in humid climates. Contractors sometimes cut corners by using low-quality plastic sheeting or failing to install proper moisture barriers, which can lead to trapped moisture and condensation within wall cavities, resulting in mold and mildew growth.
Best Practice: Use advanced house wraps like ZipSystem sheathing that act as both air barriers and water-resistant barriers to improve moisture management and energy efficiency.
Neglecting Crawl Space or Basement Ventilation
In humid climates, it’s critical to properly manage the moisture levels in crawl spaces and basements. Contractors may not install the necessary vapor barriers or ventilation systems, which can allow moisture to accumulate, creating an environment conducive to mold, wood rot, and pest infestations.
Best Practice: Install heavy-duty vapor barriers and consider mechanical dehumidification systems or ventilation in crawl spaces to control humidity and improve indoor air quality. Either choose to make the crawl space apart of the condition space or completely seperate.
2. HVAC and Indoor Humidity Control
Incorrect HVAC Sizing
Oversized HVAC systems can cool a home too quickly, failing to properly dehumidify the air. Contractors may opt for oversized units to meet quick cooling needs, but this leads to humidity problems and inefficient energy use, particularly in the Southeast's humid climate.
Best Practice: Ensure HVAC systems are correctly sized based on a comprehensive load calculation that accounts for both temperature and humidity control. This ensures better comfort, energy efficiency, and proper humidity management. Using variable speed equipment for HVAC systems, instead of single-stage units, offers significant benefits in terms of energy efficiency, comfort, and system longevity. Variable speed units can adjust the airflow and cooling or heating output based on real-time demand, ensuring that the system runs at the optimal speed for the conditions in the home. Additionally, variable speed equipment operates more efficiently over time, extending the lifespan of the system and reducing wear and tear.
Failure to Seal Ductwork Properly
Leaky ducts can allow moist air to infiltrate unconditioned spaces, leading to increased humidity and mold growth. Contractors may not use the proper sealing methods or materials, wasting energy and exacerbating moisture-related issues.
Best Practice: Keeping ductwork within the conditioned space helps maintain consistent temperatures throughout the home, reducing the risk of energy loss and improving overall HVAC efficiency. It also prevents the ducts from becoming a conduit for humidity, which can lead to mold growth, rust, and increased moisture levels in unconditioned areas like attics or crawl spaces. Additionally, this practice extends the lifespan of the HVAC system by reducing strain caused by temperature fluctuations and preventing issues related to condensation or air leaks in unconditioned environments.
3. Storm Resilience and Hurricane Protection
Weak or Improper Roof-to-Wall Connections
In hurricane-prone regions, contractors sometimes skip or improperly install hurricane straps, clips, or anchors that secure the roof to the walls and foundation. This oversight can lead to catastrophic structural damage during extreme wind events.
Best Practice: Follow Fortified Home standards by using high-strength, code-compliant hurricane straps, clips, and anchors at all critical roof-to-wall and roof-to-foundation connections. These Fortified practices ensure that the structure is resilient against extreme wind forces and meets enhanced building codes designed for hurricane protection. Additionally, insurance companies are increasingly recognizing the benefits of Fortified certified homes, offering potential savings on premiums for properties that meet these rigorous standards.
Neglecting Impact-Resistant Windows and Doors
Contractors may use standard windows and doors instead of impact-resistant versions, leaving the building vulnerable to flying debris and wind-driven rain during hurricanes or severe storms.
Best Practice: Install impact-resistant windows and doors or provide storm shutters to protect openings from high winds and debris during severe weather events.
4. Roofing and Attic Ventilation
Vented vs unvented attic spaces
Proper attic ventilation is crucial for managing heat and moisture, particularly in hot, humid climates. Traditionally, ventilated attics rely on soffit and ridge vents to create airflow that helps remove excess heat and moisture, protecting roofing materials and reducing energy costs. However, Joseph Lstiburek, one of the leading experts in building science, highlights a key downside of the traditional vented attic approach: builders often rely on the ceiling as the air barrier, which is problematic because the ceiling contains numerous penetrations (for lighting, plumbing, electrical wiring, etc.) that allow air to leak into the attic. These gaps can lead to uncontrolled airflow, moisture problems, and a significant loss of energy efficiency.
Ventilated Attic
In this method, soffit and ridge vents work together to allow natural air circulation, removing moisture and heat from the attic. While this is a standard approach for unconditioned attics, relying on the ceiling as the air barrier can compromise its effectiveness, as any leaks or penetrations in the ceiling can undermine the ventilation system.
Unvented (Conditioned) Attic
In a conditioned attic, the space is sealed and insulated to maintain the same temperature as the living areas, eliminating the need for traditional attic ventilation. This approach, as noted by Lstiburek, avoids the complications of air leaks through the ceiling and helps prevent moisture accumulation while increasing energy efficiency.
Best Practice: For ventilated attics, it’s essential to ensure a properly sealed ceiling to reduce air leakage, which may involve using advanced air barriers like spray foam or other high- performance materials. For conditioned attics, focus on air sealing, high-quality insulation, and proper HVAC design to eliminate the need for traditional ventilation while enhancing the home's overall energy efficiency.
Skipping Roof Underlayment or Using Cheap Materials
Roof underlayment is a key defense against water infiltration, especially in climates with high humidity and frequent rainfall. Contractors may use low-cost or subpar underlayment materials, reducing the roof’s ability to shed water and manage moisture effectively.
Best Practice: Use high-performance synthetic underlayment with a high moisture barrier rating (e.g., Ice and Water Shield) for enhanced waterproofing and protection against water infiltration.
5. Insulation and Energy Efficiency
Using Low-Quality Insulation or Skimping on R-Value
In the Southeast, proper insulation is essential for both energy efficiency and moisture control. Contractors may use cheaper insulation materials or opt for lower R-values to save on costs, leading to poor thermal performance and compromised comfort, particularly during hot, humid summers.
Best Practice: Install high-quality insulation materials such as spray foam, dense-pack cellulose, or fiberglass batt insulation with an adequate R-value to provide effective thermal resistance and prevent moisture migration through the walls and roof. Additionally, incorporate systems that provide thermal breaks, like Zip R Sheathing, which combines insulation with a continuous air and moisture barrier, helping to further enhance energy efficiency, reduce air leaks, and improve moisture control.
Improperly Sealing the Building Envelope
Air leaks significantly contribute to energy inefficiency, humidity problems, and long term rot and degradation of the walls assemblies. Contractors may not fully seal the building envelope, leaving gaps around windows, doors, and penetrations for plumbing or electrical systems.
Best Practice: Focus on air sealing by using high-performance caulks, foams, and gaskets to seal all gaps, ensuring that no humid outdoor air infiltrates the conditioned spaces. Proper air sealing reduces the chance of moisture-laden air infiltrating the structure, protecting insulation and maintaining the integrity of the building materials.
6. Termite and Pest Protection
Skipping Termite Barriers and Treatments
Given the prevalence of termites in the Southeast, contractors may skip installing proper termite barriers or neglect to treat wood framing with pest-resistant chemicals. This oversight can lead to serious structural damage over time.
Best Practice: Use pre-construction termite treatments, such as liquid soil treatments or baiting systems, and consider installing physical barriers (such as Pango’s Termite Barrier) or using pressure-treated lumber in vulnerable areas.
7. Site Drainage and Foundation Protection
Improper Grading and Drainage Around Foundations
Contractors often neglect the importance of proper grading and drainage systems around foundations. Without correct grading, water can pool around the foundation, leading to moisture infiltration and long-term damage to the structure.
Best Practice: Ensure the site is graded to direct water away from the foundation, and install a French drain or a similar drainage system to prevent water accumulation around the base of the house.
Failure to Install Proper Foundation Moisture Barriers
Without a vapor barrier beneath the foundation slab, moisture from the soil can rise into the structure, creating potential issues with mold, flooring damage, and poor indoor air quality.
Best Practice: Install a high-quality vapor barrier under the slab before pouring concrete, and consider moisture-resistant flooring materials to protect against water-related problems in the future.
8. Roof and Wall Intersection Detailing
Inadequate Roof and Wall Intersection Sealing
The junction between the roof and walls is a common entry point for water, particularly in high-rainfall regions. Contractors may cut corners by not properly sealing this intersection, leading to water infiltration and potential damage to both the roof and walls.
Best Practice: Use high-quality sealants and flashing around roof-wall intersections to ensure that water is directed away from critical areas and does not penetrate the building envelope.
9. Energy-Efficient Windows and Doors
Using Low-Quality Windows and Doors
Contractors may opt for cheaper, less energy-efficient windows and doors to reduce upfront costs, resulting in poor thermal performance and air leaks. This can lead to high energy bills and discomfort inside the home, especially in the hot, humid Southeast climate.
Best Practice: Install high-performance windows and doors with proper air sealing, Low-E coatings, and insulating properties to improve energy efficiency and comfort while reducing HVAC load.
Conclusion:
By cutting corners on these essential building science principles, contractors may deliver a lower-cost project initially, but they expose homeowners to long-term problems such as moisture damage, mold growth, energy inefficiency, and structural failure. By adhering to best practices in moisture management, HVAC design, storm resilience, and insulation, builders can create homes that are durable, energy-efficient, and comfortable—especially in the challenging climate of the Southeast U.S.