HVAC system duct insulation is often left unattended by homeowners and deteriorates over time. If your existing system is in poor condition, now is the time to understand what types of duct insulation are available and what is right for you.
Why Duct Insulation Is So Important?
It has been observed that a typical HVAC system loses up to 40% of treated air due to leaks, cracks and gaps in connections. Accordingly, properly insulated air ducts are better able to keep your home at a comfortable temperature and reduce your utility bills.
If it is a spot repair of a single location, you can get away with just patching the cracks. However, if your HVAC system is celebrating more than one anniversary, it is worth considering a complete replacement of its thermal insulation.
Sometimes improvements are also needed to non-old ductwork if you decide to raise the R-value. R-values vary from place to place depending on temperature and humidity. Refer to the climate zone map to determine the R-value that is right for you and to choose the proper insulation material.
Signs that things are wrong with duct insulation
If you’ve noticed that your electricity costs are steadily rising, it may be a matter of your home HVAC system’s decreasing energy efficiency. Uneven temperatures in different parts of the house are also a bad sign.
This means that uninsulated air ducts are causing warm or conditioned air to go where you don’t need it, so it’s not getting to where you expect it. And this all happens while your HVAC system is trying its best and working at overload.
Also a bad sign is a foul odor from the ventilation. There may be fungus or mold in the attic. Because of damaged insulation, harmful microorganisms can spread throughout your home, causing allergies and other health problems.
Sometimes an accidental rodent damages your network, and then you’re left wondering how to remove dead animal smell coming from air vents. Whether it’s time or an outside influence, here are 5 reasons to keep your duct insulation in good shape.
Reasons for insulating HVAC ductwork
Here are the top most important reasons why you should look into improving your air duct insulation:
- Lower utility bills
- Keep equipment from excessive wear and tear
- Improve indoor air quality (anti-dust, anti-mold, etc.)
- Reduce noise from venting
- Make the world a little greener by helping the environment.
All of these are worth it if you end up with the benefit of a comfortable home for the whole family.
Different Types of Duct Insulation for Attics
So, if replacing duct insulation is unavoidable, let’s look at what type is worth buying. If you are installing a new duct network, you should look at internal insulation. If you’re fixing up an existing network, you’ll want to focus on external one. If you’re comparing Air Duct Replacement Costs vs Repair so far, you have the opportunity to plan your ideal project.
Your choice will also be influenced by what type of ductwork you have. Some types of insulation materials can be universal, but there are some that are only used for flexible ducts or rigid ductwork.
Each technique has its own benefits. Very often, different insulations have to be applied within the same attic, even if the basic thermal material is the same. So, here are three types of duct insulation:
Duct wrap
Duct wrap is the most common type of duct insulation. Most often, this technique is used for circular ducts and always only on their external surface. Wrapping can be done either for a brand new duct network or to repair an existing one.
Insulation materials with different R-value characteristics can be used for wrapping, depending on the climate zone and the purpose of the ductwork. For example, in hot climates it is more important to insulate air conditioning ducts than return lines.
Insulating wrap is made from a variety of materials including fiberglass, rockwool, aluminum foil, bubble wrap, and nitrile rubber. The most common insulation material for wrapping ductwork is combinations of aluminum foil and mineral wool, or foil and fiberglass.
An important advantage of duct wrap is its convenience, which is very important for tight spaces. Wrapping allows you to work right off the roll, without additional marking or lengthy prep. Also, wrapping is a very cost-effective method of insulation, leaving almost no scraps or extra chunks.
Duct board
Insulating ducts with boards consists of cladding the outside of the duct with sheet insulation material. This technique is only used for rigid ducts, so it is widely used in commercial buildings with their rectangular ducts.
The use of sheet board is not very convenient in the narrow space of a home attic, but sometimes it is easier to make a square box of sheet material than to wrap an intricately shaped duct joint. Homeowners can always combine any insulating types in their attic to their liking.
Duct boards are most commonly made of mineral wool or fiberglass. In addition to the insulation itself, these materials can perfectly absorb noise from sheet metal ducts.
Duct liner
The duct lining solution is used to insulate rigid ductwork only. This insulation type is tried on the internal surface of the duct, not on the outside like the others.
Air duct lining is used in large HVAC systems to ensure that there is enough room inside the duct for both air passing and for insulating material in the right amount to provide proper R-values.
For duct lining, stone wool is most widely used, as perforated metal sheet rockwool is a common sound insulating material. But despite the many benefits of lining few homeowners want to see such wide ductwork in their home.
3 Types of Duct Insulation Materials
Fiberglass insulation
Fiberglass is widely used in insulating attics, heating and air conditioning ducts. Fiberglass insulation is available in a variety of formats – in fluffy fiber for spraying, in boards and rolls. It is convenient in tight attic spaces and any homeowner can take that thickness of fiberglass to get properly insulated air ducts.
In addition to an efficient HVAC system, fiberglass ducts give you some other benefits as well. Fiberglass insulation has a long lifespan, is fire resistant, and tolerant of weather changes.
Fiberglass insulated ducts are safe from insects and rodents, as well as mold and fungus. All these factors guarantee excellent indoor air quality in your home.
Rockwool insulation
To insulate HVAC ductwork for decades at a time, consider mineral wool as a duct lining. In addition to its many positive properties, rock wool is an excellent sound absorber. Also, rockwool is made of recycled materials, fireproof, invulnerable to insects, mold, and more.
It is worth mentioning that stone wool has insulation values of 3.0 to 3.3 per inch, which is higher than fiberglass (2.2 to 2.7 per inch). However, it is more expensive to insulate ductwork with rockwool.
In addition to the cost of the insulating material itself, consider that interior lining is more costly than exterior wrapping. Also, the air ducts need to be oversized, which requires a major remodel of the HVAC system in general.
Polyethylene insulation
If we consider exterior insulation without duct renovation, let’s focus on PE foam. This insulation type is completely invulnerable to moisture. Once wet, fiberglass and rockwool temporarily lose their energy efficiency. PE insulation is absolutely devoid of this disadvantage.
Polyethylene is widely used in private and commercial construction. It is a lightweight, strong and moisture resistant material.
Because of this, polyethylene insulation is used both inside and outside the house. Each homeowner can choose what they are more comfortable with – duct boards, large rolls, wraps, or PE pipes.
FAQs
What is insulation in duct system?
Duct insulation is needed to keep the air inside at the temperature you set. For this purpose, various materials are used that do not allow energy to pass through. To insulate ductwork, you can use boards, rolls, and wraps made of rock wool, fiberglass, polyethylene foam, and foil.
What are the three types of ducting in HVAC?
Talking about ductwork in HVAC system we can name rigid, semi-rigid and flexible ducts. Reliable insulation methods are available for each of them.
How thick should duct insulation be?
The thickness of the insulation layer will vary for different materials and various climates. Also supply and exhaust ventilation ducts may need different thicknesses, depending on whether heating or air conditioning is more important in your climate.
So, What Type of Insulation Is Best for Ducts?
The most common type of duct insulation is fiberglass wrap combined with foil or polyethylene. Rockwool is also popular in board sheets, rolls, and interior lining.
Each of these materials has its own advantages. To choose the one that is right for you, evaluate whether you want interior lining or exterior insulation. Duct lining is more expensive than using duct board or fiberglass, but it lasts longer.
Either way, duct insulation is something worth doing to get improved indoor air quality. Looking to expand your attic insulation project? Here’s Attic Insulation Removal and Replacement if that’s just what you need.