What is Class 1 insulation?

Understanding Class 1 Insulation

Achieving a Class 1 insulation installation is vital for constructing a high-quality, energy-efficient residence. This classification signifies that the insulation is installed expertly, free of any moderate or significant flaws. Although Class 1 installation should be standard practice within the residential construction sector, there are times when it is unmet. Inadequate installation results in a home failing to reach its full potential, which negatively impacts builders, installers, and insulation manufacturers.

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RESNET's Grading Standards Explained

The Residential Energy Services Network (RESNET) has established specific criteria for grading insulation installation, which HERS raters use to assess the quality of installation. When evaluating insulation, HERS raters notably check for voids where insulation is absent, gaps, and compression issues.

Overview of RESNET Grading Levels:

Class 1 - Minor Defects

Occasional tiny gaps are permissible, but voids cannot span from the interior to the exterior (meaning they cannot cover the entire width of a wall cavity). The insulation should comply with manufacturer specifications and must fit correctly around electrical junction boxes, as well as being split around pipes and wires. A compression or an incomplete fill of 2% or less is acceptable, provided that the empty spaces account for less than 30% of the intended thickness.

Class 2 - Moderate Defects

This classification can include slight compression and missing insulation up to 2%. There may also be moderate to recurring gaps around wiring, plumbing, electrical outlets, and other obstructions. It's important to note that missing insulation is assessed differently than compressed insulation in this grading framework.

Class 3 - Substantial Defects

This level includes significant gaps and voids, where missing insulation exceeds 2% of the total area. Any installation failing to meet the minimum requirements for Class 1 or Class 2 is considered Class 3.

For a complete overview, click here to access the full RESNET Manual, specifically Appendix A, pages A-11 through A-16.

Tools for Achieving Class 1 Installation

This site provides extensive resources, including detailed instructions, video guides, and visual aids covering:

• Installation Preparation. Our section on installation considerations assists in prepping for insulation work, detailing the necessary pre-installation steps.
• Correct Installation Methods. Our mobile-optimized pages illustrate location-specific installation techniques in a clear, easy-to-follow format.
  • Attic and Ceiling Insulation
  • Wall and Knee Wall Insulation
  • Floor Insulation
• PDF Guides for Download. We also provide downloadable pictorial guides for those who prefer a printable format, including a Spanish version.
• Installation Video Series. Visit our YouTube channel for our three-part video series available in English and Spanish.
• Short video clips on installation tips. If concise information is what you need, this playlist targets specific aspects requiring extra attention.
• 25-Point Inspection Checklist. To ensure proper installation, this checklist can serve as a valuable reference.

In addition, the RESNET Manual suggests various NAIMA publications as references for achieving proper insulation installation:

• Mineral Fiber Insulation Installation Recommendations
• Loose Fill Fiberglass Installation Recommendations

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For more information regarding insulation, please refer to class 1 insulation rubber foam.

Spray foam is another method that excels in filling gaps around obstructions in wall cavities, providing both insulation and air sealing benefits. This type, made from various formulations including petroleum and soy, is available in open-cell and closed-cell types, the latter providing a vapor barrier. Alternatively, cellulose or mineral wool can be sprayed into open cavities with the help of adhesives and water before drying.

Consult the foam rubber supplier for guaranteed expert advice and consultative services!