Many people think they can save some money by making the ductwork for their HVAC system out of wood. This thought is valid since wood is cheaper than aluminum and stainless steel, the most commonly used materials for ductwork. However, before going that route, you must know some crucial facts about wood.
You can’t make ductwork out of wood for safety reasons. Wood is not a fire-resistant material, meaning it can catch fire and spread flames throughout your house. Moreover, wood cannot withstand high temperatures and can easily warp or crack under heat, leading to air leaks and inefficiency.
In the rest of this article, I’ll discuss the essential facts of why you should avoid making ductwork out of wood. The focus is to ensure your ductwork works efficiently while keeping your home and family members safe. Let’s get started!
7 Important Facts You Need To Know About Wood and Ductwork
Ductwork is essential to your HVAC system since it carries and distributes cool or warm air throughout your house.
The material you use for the ductwork is essential as it determines the system’s efficiency. An efficient ductwork material must meet the following qualities:
- Fire-resistant: The circulated air can get too dry, posing a fire risk. Therefore, the material should not be combustible.
- Able to withstand high temperatures: HVAC systems can generate air with temperatures exceeding 78°F (25.56°C). As a result, the material must withstand such high temperatures without warping.
- Durable: You want the ductwork to serve you for as long as your house exists. This benefit can only happen if you go for a durable material.
- Efficient in air distribution: The material should not have cracks or holes that can cause air leaks, leading to inefficiency.
Wood does not meet any of the above qualities, making it unsuitable for ductwork. The following are the essential facts that make wood unsafe for ductwork:
1. Wood Is Highly Combustible
Wood is a combustible material since it has cellulose. When exposed to high temperatures, wood can catch fire and spread flames throughout your HVAC system, posing a threat to your home and family.
It’s worth noting that HVAC systems use fuel to warm the air as it moves through the ductwork. The fuel used is highly flammable, making it even more crucial to use a fire-resistant material for the ductwork.
Using wood in the presence of this fuel poses a high fire risk for your home. If the fuel catches fire, the wood will exacerbate the condition by spreading the flames. Therefore, avoiding wood in your HVAC system’s ductwork is best.
Since wood is highly flammable, you may wonder if wooden ceilings are a fire hazard. Check out the article I’ve written on this issue for points to consider before choosing your wooden ceiling. [Are Wooden Ceilings a Fire Hazard? What You Need to Know]
2. Wood Cannot Withstand High Temperatures
The air circulated through your HVAC system can reach high temperatures, exceeding 78°F (25.56°C). Subjecting wood to such temperatures can cause warping. When this happens, you expose the wood to thermal expansion, which can cause swelling and shrinking.
A swollen or shrunk ductwork distorts the connection between the furnace and the plenum. Since the plenum connects to the main trunk line that runs throughout the home, this distortion reduces airflow. Therefore, some rooms may not receive conditioned air due to insufficient airflow in the ductwork.
Thermal expansion exposes the wood to thermal shock as different sections expand and contract differently. When this happens, the wood is most likely to crack, exposing your HVAC system to the worst nightmare, air leaks.
Leaking air ducts channels the conditioned air to unwanted areas like the attic and basement. Consequently, your home won’t receive sufficient conditioned air due to the loss. When this happens, the HVAC system tends to work harder to make up for the loss, leading to higher energy bills and quicker wear and tear of the system.
Not only does this decrease the efficiency of your HVAC system, but it also poses a safety threat. Air leaks can expose you and your family members to toxic gases like carbon monoxide in the air circulated by the HVAC system.
3. Wood Is Not a Durable Material
When properly installed and maintained, metal ductwork can last for decades. However, wood cannot match the durability of metal.
Wood is not durable enough to withstand constant air pressure and movement. The constant movement can lead to cracks in wood, exposing your HVAC system to air leaks.
Apart from the system’s pressure, wood has low natural durability. The life expectancy of untreated wood ranges from eight to ten years. Therefore, if you use wood for your ductwork, you must be prepared to change it every eight to ten years.
On the other hand, metal ductwork can serve you for decades before any replacement or repair is necessary. Therefore, choosing a more durable material like metal is best for your HVAC system’s ductwork.
4. Wood Is Harder To Maintain and Clean
Maintaining and cleaning wood ductwork is much harder compared to metal ductwork.
Wood is more susceptible to debris buildup, leading to clogs and reduced airflow in the system. Inadequate airflow can cause your HVAC system to work harder, reducing efficiency and shortening its lifespan.
Moreover, wood attracts dust and pollen due to its porous nature. This accumulation can trigger respiratory issues and worsen allergies for your family members.
On the other hand, you can easily clean metal ductwork using a brush or vacuum attachment. Its smooth surface also reduces the buildup of debris, making it easier to maintain.
5. Wood Is Prone to Pests
Due to its organic nature, wood is susceptible to pests. Pests such as termites, beetles, and carpenter ants are the worst in dry wood. These pests affect the wood in the following ways:
- Tunneling and burrowing which leads to a weakened structure
- Contamination from their excrement
- Spreading of diseases
What do you think happens to the ductwork when pests burrow through the wood? Air leaks.
Some signs of air leaks in your ductwork include:
- Increase in utility bills
- An excessively dusty home
- Reduced indoor air quality
- Uneven home temperatures
Pests can also enter your HVAC system through the wooden ductwork and infest other areas in your home. Therefore, opting for a material that is not as attractive to pests, like steel, can protect your HVAC system and home.
6. Wood Is Prone to Mold Growth
According to USDA, wood is a hygroscopic material. This designation means that wood absorbs moisture depending on the environmental humidity level; the higher the humidity, the more moisture it absorbs.
Excessive moisture in your ductwork, especially in areas with high humidity, creates a suitable environment for mold growth. Mold in the ductwork reduces the system’s efficiency in spreading conditioned air throughout the home.
Moreover, mold can cause various health problems for you and your family.
Some mold health risks include:
- Watery eyes
- Runny nose
- Difficulty breathing
You may wonder how the mold will travel from the ductwork to affect your family. It’s simple; the HVAC system circulates air throughout the home. Thus, mold spores can travel with that air to your house.
In contrast, metal ductwork is not as prone to mold growth because it does not absorb moisture like wood. These features make it the best option for your family’s safety.
7. Wood Joints Are Prone to Leaks
Ductwork involves many joints. You’ll have to bend the system in different locations to fit around your home’s layout.
Bending metallic or silicone-based ductwork creates a tight seal, reducing the risk of air leaks. However, bending wood to make joints can cause cracks and gaps in the material, leading to air leaks.
These leaks can result in higher utility bills and reduced indoor air quality for your family.
Best Materials for Ductwork
Since the air ducts provide thermal comfort for your home, you must use materials that enhance their efficiency. Such materials include:
- Sheet metal: This is the most common material used for air ducts. It’s a preferred option since it’s easy to clean, durable, and doesn’t accumulate dust. This material is mainly made from galvanized steel, giving it a soft surface and reducing the risk of air leaks.
- Fiberglass: This material comprises glass fibers coated with a resin binder, making it durable and non-porous. The smooth surface also reduces dust accumulation and makes it easier to clean—so this is your go-to material to reduce the air conditioner’s noise.
- Silicone: This material has a higher temperature tolerance than metal or fiberglass. It’s also highly flexible and durable, making it suitable for tight spaces.
- Flexible ducts: These ducts comprise plastic polymer and wire. These ducts make the best option for people on a tight budget as they are cheaper and easier to install.
While wood may seem like a cost-effective option for your ductwork, there are better choices regarding air quality, energy efficiency, and overall durability. Wood is prone to thermal expansion, air leaks, pest infestation, and reduced durability. These factors will reduce your HVAC system’s efficiency.
Investing in materials like sheet metal, fiberglass, silicone, or flexible ducts is best for your HVAC system’s long-term success. Although these materials may seem expensive initially, they are worth it for an efficient system.