Insulation Types & Quality: Good Insulation vs. Bad Insulation

EXAMPLES OF GOOD INSULATION

Attic space with exposed wooden beams and a thick layer of white insulation on the floor.
Empty attic room with pink insulation on the floor, wooden wall paneling, and a small arched window.

Cellulose (Blown-In) Insulation

This is cellulose insulation, also known as blown-in insulation. It is one of the most common insulation types found in homes, especially in attics. When properly installed, it fills cavities evenly and helps reduce heat loss, improve comfort, and increase overall energy efficiency.

Fiberglass Loose-Fill Insulation

This is fiberglass loose-fill insulation. It is less common than cellulose but serves a similar purpose. Fiberglass loose-fill is typically found in attics. In walls, fiberglass is more commonly installed in batt form. (Fiberglass insulation can appear pink or yellow.)

Fiberglass Batt Insulation

These are fiberglass batts. This type of insulation is commonly found in interior walls, knee walls, attic ceilings, basement walls, basement ceilings, and crawl spaces. When installed correctly, batts help slow heat transfer and improve indoor comfort.

Interior of a room under construction with pink insulation on the wall and exposed wooden framing.

EXAMPLES OF POOR / INADEQUATE INSULATION

View inside an attic showing wooden beams, insulation, and debris.
Insulation installed in an attic with exposed wooden beams and a floor covered with blown-in insulation.
Attic with exposed wooden beams, insulation on the floor, and a small skylight window in the roof.

Old or Degraded Fiberglass Insulation
 This is an example of old fiberglass insulation. When insulation appears dirty, compacted, or no longer fills the cavity, it is no longer performing effectively. In these cases, new or additional insulation is typically recommended.

Little to No Attic Insulation

This attic has little to no insulation. Without adequate insulation, air can easily seep in and out of the home, leading to higher energy costs, uncomfortable indoor temperatures, and increased strain on heating and cooling systems.

Poor Wall Insulation

This is an example of poorly performing wall insulation. Visible discoloration, gaps, or insulation falling out of the wall cavity indicates reduced effectiveness and potential air leakage. These conditions can significantly impact comfort and energy efficiency.

Understanding R-Value

What Is R-Value?

R-value measures how well insulation resists heat flow. The higher the R-value, the better the insulation performs at keeping heat inside during the winter and outside during the summer. The thickness and type of insulation both affect R-value.

Attic R-Value

If an attic has less than R-18 (approximately 5–6 inches of insulation), additional or new insulation is recommended. The ideal attic insulation level is R-31 or higher for improved energy efficiency and comfort.

Floor R-Value

If floor insulation is less than R-11 (approximately 3–4 inches), additional or new insulation is recommended. The ideal floor insulation level is R-30 or higher, especially over unconditioned spaces.