Get matched with top doorbell installation pros in Sidney, IL

You do not always need to remove old insulation before adding new. If the existing insulation is in good condition—not wet, physically damaged, moldy, or infested with pests—you can add new insulation directly on top of it for a compounding effect. You can also mix different types, such as adding blown-in insulation around existing fiberglass batts.

However, removal is recommended if the old insulation is compromised by water damage or pests. You should also remove it if you plan to install a different type of insulation, like switching from roll or batt insulation to spray foam. If the existing insulation is very old or damaged, you will likely get more benefit from removing it and starting fresh.

If you’re a savvy DIYer around the house, own the basic tools, and have enough time on your hands, you can definitely install fiberglass insulation yourself. Doing the work yourself will certainly keep overall insulation costs down. However, if you’re not confident in your handy skills around the house, call in a professional.

Air duct insulation typically lasts for 10 to 15 years or even longer, depending on the material and maintenance. It's important to conduct periodic inspections to check for signs of deterioration, such as water damage, tears, or general wear. If you find any of these issues, it may be time for repairs or a full replacement. You might also consider upgrading your insulation even if it's in good shape to improve your home's energy efficiency and enhance your HVAC system's performance with newer, more effective materials.

The most affordable way to insulate behind unfinished walls is to install fiberglass batts or rolls. These total around $0.75 per linear foot, with the width matching the gaps between standard studs perfectly. However, it’s important to consider the R-value of your insulation and the climate in your area, as fiberglass insulation isn’t the best in terms of preventing heat transfer. Plus, the most affordable option may cost more on electricity bills over time. The most affordable way to insulate behind finished walls is to leave them up and use blown-in insulation to avoid drywall replacement.