Key Considerations When Installing Wall Insulation


Insulation plays a pivotal role in ensuring a building’s overall health, sustainability, and comfort. Due to continuing advancements in building science, a growing number of high-performance insulation products are available. When it comes to insulating walls, in particular, properly-installed insulation results in notable thermal and acoustic benefits.

Adding insulation beneath drywall in a typical interior wall assembly can significantly improve sound control and increase the Sound Transmission Class (STC) rating of the wall ceiling or floor assembly. In addition, well-insulated walls help to control  heat flow, contributing to more comfortable spaces while reducing energy costs.

Choosing the Right Product for the Job

Several commonly specified types of insulation can be used in wall cavities.

Fiberglass batt insulation, such as CertainTeed InsulPure™, is optimally suited for both residential and commercial applications. When installed in stud wall cavities, the batts deliver strong thermal performance and noise control.

InsulPure is GREENGUARD® Gold Certified and UL-validated to be formaldehyde-free, making this evolution of insulation a healthy choice for both installers and end users.

In some cases, fiberglass roll insulation may be a desirable option. Compression packaged and encapsulated for ease of handling, CertainTeed EasyTouch™ roll insulation provides outstanding thermal and acoustic attributes. While this insulation type is typically installed in attics and crawl spaces, above unheated garage spaces, and for fireplaces, it can be used to insulate walls, and anywhere a Class A fire rating is required. 

Blown-in insulation can be a good choice for areas that can’t accommodate other types of insulation, such as difficult-to-reach wall cavities and small nooks. Also known as fiberglass loose-fill, this insulation type is installed via a machine. Blowing machines vary in size, and some – for example, the Bolt™ 3 – are portable, making them easy to handle by even a small crew.

Installation Tips

To achieve the best result when installing insulation in wall cavities, it is important to follow recommended best practices, such as these guidelines from NAIMA (North American Insulation Manufacturers Association).

  • Cavity Fill – Batts or loose-fill should fill all standard and narrow cavities completely with no gaps at the top or bottom.
  • Electrical Wiring – Insulation should be split or cut to fit around wiring.
  • Electrical Boxes – Batts should be cut to fit around electrical boxes, with a piece placed behind each box.
  • Plumbing – Insulation should be placed between the outside wall and the pipes. If kraft facing is used, it should be in substantial contact with the gypsum board.
  • R-value – The R-value should be marked visibly on the insulation, whether faced or unfaced. The R-value should meet or exceed minimum code requirements.
  • Fitting – Batts should friction-fit snugly in the cavity. Faced batts can be inset- or faced-stapled, as needed. If inset-stapled, batts should not be overly compressed.
  •  Vapor Retarder Materials – When required, appropriate vapor retarder materials may include kraft facing, continuous polyethylene sheeting, vapor retarder paints, and “smart” vapor retarders. (Note: Polyethylene should only be used in very cold climates.)
  •  Vapor Retarder Placement – Vapor retarders should be oriented towards the “warm in winter” living area, except in extremely humid areas. (Note: Kraft facing should never be left exposed.)
  • Vapor Retarder Integrity – Taping vapor retarder facings is not standard practice. Small tears and gaps are not expected to cause moisture issues, but can be repaired, if desired.
  • Bay Window – The outside wall, extended floor, and ceiling should be insulated.
  • Window and Door Areas – Spaces around windows and doors should be filled with insulation, or caulked. Do not overstuff.
  • Band Joists – Insulation with a nonflammable facing should be used for band joists.

 Lasting Benefits

When properly installed, wall insulation enhances a structure’s mechanical heating and ventilation systems while helping to maintain desirable temperatures and dampening unwanted noise.

Specifying and correctly installing high-performance insulation in wall assemblies will contribute to a healthier, more energy-efficient structure and long-term comfort for occupants. 

If you have any questions, we’re always available to assist you. Don’t hesitate to reach out!

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