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When Is Insulation Required on Air Ducts?

When Is Insulation Required on Air Ducts?

When Is Insulation Required on Air Ducts?

People often ask if duct insulation is required. Since air ducts are prone to leakage and heat loss, insulation helps them work more efficiently; it can even lower your electric bill. However, your ducts may not need insulation if you live in a mild climate and your building has a strong thermal envelope. And if the ductwork you install is pre-insulated, you don’t need to insulate it further.

When Is Duct Insulation Required?

Duct insulation isn’t required by national law. It’s governed by codes in individual states. In California, air ducts enclosed in conditioned spaces aren’t required to be insulated. The ductwork in unconditioned spaces must have insulating materials rated at either R-6 or R-8 (in the typical climate zones of the Central Valley), according to Title 24 requirements. Some insulation requirements vary from one jurisdiction to another.

The R-value of insulation indicates its ability to resist the flow of heat from warm to cool areas. Therefore, it compares how well insulation keeps heat out of your home in summer and indoors during winter. The higher the R-value, the more efficient the insulating material.

Here are some reasons why duct insulation may be required:

  • Air Ducts Are Prone to Leakage: Joints connecting sections of sheet metal or fiberglass ducts are prone to air leakage, which reduces HVAC efficiency. Insulating the joints can provide a seal that prevents leakage.
  • The Duct Material Has Poor Efficiency: Sheet metal ducts are among the most energy-efficient. However, flexible air ducts tend to lose energy due to tears and other types of damage. Insulation can compensate for the lower efficiency rating of thin, flexible ducts.
  • In Unconditioned Areas: Ducts in unconditioned areas like basements, ceiling spaces, and other locations should be insulated to avoid condensation that can increase humidity and allow mold growth. Insulation can also block noise from ducts and other parts of your home.
  • To Help Keep Ductwork Sanitary: Dust particles and bacteria don’t settle on insulated ductwork as easily as uninsulated ducts. Therefore, insulation can help improve indoor air quality and avoid airborne illnesses associated with poorly insulated and maintained ducts.
  • Old Ducts: If your older ductwork is in relatively good condition but not highly efficient, you can choose to insulate it. This can avoid having to replace ducts immediately and improve your HVAC system’s performance.

International Energy Conservation Code (IECC) Requirements

Except for factory-installed ducts, plenums, and casings or exhaust air ducts where the temperature difference between the inside and outside of the duct is less than 15℉, the IECC calls for insulation to be installed in supply and return ducts:

  • In attics vented to the outside
  • Within unventilated attics
  • Exposed on building exteriors

The IECC also requires insulation for:

  • Return ducts in indirectly conditioned ceiling spaces
  • Exterior walls of return plenums that double as ceiling space
  • Supply outlets in return plenums
  • Supply runouts of return plenums
  • Supply/return ducts in a vented crawl space
  • Below-grade supply and return ducts

Can I Install Duct Insulation Myself?

We recommend having a professional insulate your ductwork. It requires a bit of patience and attention to your safety, especially when installing fiberglass insulation. A professional has all the knowledge and tools needed to choose the best type of insulation and install it with precision.

However, if you decide to go the DIY route, make sure to wear protective gear like goggles, gloves, and a dust mask. The project will take a couple of days; it requires waiting for the sealant to dry. But first, old insulation must be removed and leaks must be repaired. The new insulating material must then be precisely measured, cut, and wrapped/secured around the duct. Safe to say, it isn’t the easiest home improvement project.

How Long Does Duct Insulation Last?

It can be 10 to 15 years before you need to replace or upgrade your duct insulation. However, it’s wise to check for signs of wear or damage. Any insulation that’s torn or water-damaged should be replaced. Also, consider upgrading it if you think your HVAC system can be more energy efficient.

How Thick Should Duct Insulation Be?

Fiberglass foil-faced R-6 duct insulation is 2 3/16 inches thick and is available as 75-foot x 4-foot wide rolls. Meanwhile, R-8 insulation is 3 inches thick and available in 50-foot x 4-foot rolls. But a standard R-4.2 insulating material is only 1½ inches thick. It comes in 100-foot-long x 4-foot-wide rolls.

Contact Monarch Home Services for Help with Duct Insulation

Properly insulating your ductwork requires a few technical skills, so it’s best to hire a professional. Replacing insulation takes a lot of effort. Our skilled team is efficient and can determine the best type of insulation and where to install it. Proper insulation can lower your electric bill and have many other benefits. For help with duct insulation and other HVAC services, contact us online or call (661) 215-6745.

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