Displaced Wall Insulation: Simple Solution

In the ever-evolving world of residential construction, we can use old-school techniques to help solve a modern insulation challenge – displaced wall cavity insulation.

This bonus room knee wall is a prime example of where netting the insulation will prevent displacement.

Two terms from bygone eras of construction – “sarking” and “scrim” – offer valuable insights into solving a common problem in today’s homes: compressed insulation.

Initially referring to the boards that support roof tiles, Sarking has evolved to mean any protective layer beneath roofing materials. On the other hand, Scrim is a term borrowed from the textile industry, describing a lightweight, open-weave fabric used for reinforcement. In construction, Scrim often refers to the facing on insulation batts or the mesh used to hold insulation in place.

These concepts from the past can inspire modern solutions to the persistent issue of compressed insulation, particularly in challenging areas like attics with tiered floors and knee walls.

Displaced and Compressed Insulation

A thermal bypass refers to any pathway that allows uncontrolled air movement within a building, typically leading to unwanted heat transfer. This can significantly reduce a structure’s energy efficiency, as conditioned air (heated or cooled) escapes through these bypasses while unconditioned air infiltrates. Common thermal bypasses include gaps and cracks around windows and doors, attic hatches, recessed lighting, and areas where different building materials meet. Addressing these bypasses through proper sealing and insulation is crucial for maintaining energy efficiency and indoor comfort.

A typical scenario is a tiered attic floor with a rough construction ladder leading to a higher elevated area. Over time, foot traffic and general usage can cause batt insulation to work loose or become compressed. This compression significantly reduces the insulation’s R-value, increasing heat loss in winter and heat gain in summer.

When insulation isn’t set firmly in place, gaps allow hot or cold attic air to bypass the insulation’s thermal barrier, compromising the home’s energy efficiency.

A Modern Solution with Old-School Roots

Drawing inspiration from the concepts of Sarking and Scrim, we can address this issue effectively using insulation netting. This method combines the protective aspect of Sarking with the reinforcing properties of Scrim.

Here’s how it works:

  1. Install plastic netting across the floor joists or wall studs before placing the insulation.
  2. Lay the batt insulation over or behind the netting, ensuring it fills the cavity.
  3. Secure the netting tightly, creating a barrier that holds the insulation in place.

This approach offers several advantages:

  1. Maintains Loft: Unlike rigid barriers like plywood or strips of wood, netting allows the insulation to maintain its full loft. This “fluffiness” is crucial for preserving the insulation’s R-value.
  2. Prevents Compression: The netting provides enough give and play to prevent pinching or compressing the insulation, a common issue when using rigid strapping methods.
  3. Allows Air Movement: The open weave of the netting permits some air movement, which can help prevent moisture buildup while still keeping the insulation in place.
  4. Easy Installation: Plastic netting is lightweight and easy to handle, making it ideal for DIY projects or professional installations in tight spaces.
  5. Cost-Effective: This solution is typically less expensive than wood and can be easily replaced or adjusted.

By implementing this netting technique, homeowners can ensure their insulation remains effective over time, even in high-traffic attic areas. It’s a prime example of how merging old-school wisdom with modern materials can solve persistent construction challenges.

Spray Foam Alternative

The video recommends using spray foam insulation in attics, especially for knee walls and other areas with uneven shapes.

Spray foam insulation can provide a more effective and long-lasting solution than traditional fiberglass batt insulation.

Remember, proper insulation is critical to maintaining your home’s energy efficiency. Whether tackling a new build or updating an existing space, consider enclosing the wall cavity, using spray foam, or for the least expensive method, netting your insulation to keep it fluffy, effective, and firmly in place for years.

Fully Enclosed Wall Cavity

Fully enclosing the wall cavity will help control displaced insulation and create an air barrier. Of all the methods discussed, this one will seal and prevent displacement and it meets the Energy Star best practice when meeting the Energy Star Thermal Bypass Checklist.

Always contact your local AHJ, the authority having jurisdiction, to maintain local code compliance. Learn More About the Energy Star Checklist. Use the energy rater Thermal Bypass Checklist.

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