What Happens If You Compress Insulation?

Fiberglass batt insulation is an excellent choice for insulating your home. Proper installation is key, as failure to follow the manufacturer’s recommendations may lead to suboptimal results.

At REenergizeCO, we strongly recommend professional installation of fiberglass batt insulation. Our experts have the knowledge and experience to position batts for maximum performance.

Can Insulation Be Packed Too Tightly?

Yes, it can. It all comes down to the R-value, or the insulation’s resistance to heat.

Compressing fiberglass batts enhances the R-value per square inch because the material is packed tightly together. However, compression also reduces the R-value of the batt overall because you lose some inches of insulation when it is packed tightly.

Does It Matter If Insulation Is Compressed?

The North American Insulation Manufacturers Association (NAIMA) notes that, while the R-value listed on fiberglass batts assumes standard wall cavity dimensions, there are circumstances where compression may be needed. If it is necessary to compress batts to fit the space, obtaining full coverage is essential to avoid gaps and losing too much of the R-value.

Gaps in fiberglass insulation can lead to a number of problems:

• Higher utility bills due to air leaks
• Drafts and temperature inconsistencies inside the home
• Condensation in the walls and ceilings; this can lead to mold and mildew
• Formation of ice dams in the wintertime
• Decreased indoor air quality

NAIMA notes that fiberglass batt insulation must be compressed to the exact depth of the wall cavity. Insulation professionals can evaluate the wall cavity and make the precise adjustments needed to insulate the space without sacrificing performance.

It is also important to note that some fiberglass insulation products may be damaged if they are compressed. Damage to the insulation or sheathing can make it less effective, as well as reduce the longevity of the insulation.

What Happens If You Compress Blown-In Insulation?

Like batts, compressing blown-in fiberglass insulation improves the R-value per square inch while diminishing the overall R-value. Also like fiberglass batts, some amount of compression is OK if the cavity is completely filled.

Installing blown-in insulation by yourself can be tricky. Overfilling the cavity can damage the wall, as well as hamper airflow and seal in moisture. For best results, we recommend leaving blown-in insulation to a professional.

Read More: How Long Does Fiberglass Insulation Last?

How Much R-Value Is Lost When Compressing Insulation?

R-value is based on the labeled thickness of the insulation material. When fiberglass batts are compressed, both the thickness and the R-value go down. The deeper the cavity, the more the R-value is reduced.

We compared the recommended R-value for the areas of a home in Metro Denver against NAIMA’s estimate for how R-value is reduced following compression. Key takeaways include:

• Attic Insulation (R-49 recommended)
  • 14 inch R-49 insulation is reduced to R-44 when compressed to fit an 11 ⅞ inch space.
  • Further compression of 5/8 of an inch (11 ¼ inches) reduces the R-value to R-42.
• Crawl Space Insulation (R-19 recommended)
  • The labeled thickness for R-19 insulation is 6 ¼ inches. When compressed to fit a 5 ½-inch cavity, the R-value is reduced to R-18.
  • R-14 is the remaining value when compressed to fit a 4-inch space.
• Wall Insulation (R-13 recommended for walls above grade)
  • 3 ½ inch R-13 insulation has a value of R-10 when it is compressed to fit a cavity that is 2 ½ inches deep.

It would be nice if fiberglass batt insulation could just be installed without having to worry about making it fit. Unfortunately, the dimensions of framing cavities don’t always match the labeled thickness of home insulation. If this is the case, the fiberglass batts may need to be compressed.

Compressing home insulation doesn’t render it completely ineffective. And, depending on the circumstances, lost R-value can be restored by topping off the cavity with loose-fill insulation. The best way to make informed decisions about insulating your home is to consult an experienced professional.

Get Help with Your Home Insulation!

At REenergizeCO, our mission is to help customers in Denver, Fort Collins, and all over the Colorado Front Range make their homes more energy-efficient and affordable. Properly installed home insulation can make an enormous difference in how much energy you use, what you pay for electricity, and the comfort of your home.

Fiberglass batts are among the most common options for insulating a home. They are often used in new construction, and we frequently see them in older homes as well. Our efficiency crews understand the delicate balance involved in compressing fiberglass batt insulation to fit a wall cavity and maximizing the R-value. We evaluate your home’s insulation and make individualized recommendations for upgrades.

Reach Out to REenergizeCO Today

We realize you have many options for insulating your home. Both the choice of materials and the number of insulation contractors in Denver and Fort Collins can make it difficult to choose. Team members at REenergizeCO are committed to helping you make an informed decision and find the best solutions for your home, your family, and your bank account.

Contact REenergizeCO to discuss your insulation options!