When to Use composite material duct corner？

Air duct aluminum foil is a widely used material in ventilation and air - conditioning systems. It is made of high - quality aluminum foil through special processing techniques. With its unique properties, this material plays an important role in various buildings and industrial places.

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Types and Structures

Air duct aluminum foil can be divided into various types according to material and function. Pure aluminum foil duct material takes high - purity aluminum foil as the core, usually adopting a single - layer structure. It has a smooth surface and metallic luster, and can be directly attached to the surface of the air duct to play the basic role of heat preservation and moisture proof, which is suitable for ordinary ventilation systems with low heat preservation requirements.

Aluminum foil composite duct material is more common, and its structure is mostly multi - layer composite. There is the aluminum foil + glass wool composite structure. Aluminum foil as the outer layer can block external moisture and heat, and the middle glass wool layer enhances the heat preservation effect. This structure is suitable for air - conditioning systems with large temperature differences. There is also the aluminum foil + polyethylene composite structure. The polyethylene layer is light and has certain elasticity, which can improve the impact resistance of the overall material, and is often used in air duct environments that need mild protection.

In addition, there is embossed aluminum foil duct material. The surface of the aluminum foil is embossed to form regular lines. This structure can enhance the tensile strength of the aluminum foil and reduce deformation caused by temperature changes, which is mostly used in parts such as air duct corners that are easy to be stressed.

Conventional Thickness Parameters

The thickness of air duct aluminum foil needs to be determined according to the use scenario and functional requirements. The conventional thickness range of pure aluminum foil is narrow, generally between 0.03mm and 0.1mm. Pure aluminum foil of 0.03mm - 0.05mm is often used in small air ducts that are sensitive to weight and have low heat preservation requirements; 0.06mm - 0.1mm is suitable for medium - sized ventilation systems, which can provide more stable protection.

The thickness of composite aluminum foil varies due to different composite layers. The total thickness of the aluminum foil + glass wool composite structure is usually 5mm - 20mm, among which the aluminum foil layer is 0.05mm - 0.1mm, and the glass wool layer is 4.95mm - 19.9mm. The greater the thickness, the stronger the heat preservation performance, which is suitable for air - conditioning systems in cold or hot areas. The total thickness of the aluminum foil + polyethylene composite structure is mostly 3mm - 10mm, the aluminum foil layer is 0.04mm - 0.08mm, and the polyethylene layer is 2.96mm - 9.92mm, which is suitable for ventilation pipes in normal temperature environments.

The thickness of embossed aluminum foil is slightly larger than that of pure aluminum foil of the same specification, generally 0.05mm - 0.12mm. The embossing process will not significantly increase the thickness, but it can improve the structural stability of the material.

Performance Characteristics

Air duct aluminum foil has excellent thermal insulation performance. Aluminum foil itself is a poor conductor of heat, which can effectively prevent the transfer of heat. When applied to the surface of air ducts, it can reduce the heat exchange between the air inside the ducts and the external environment. Thus, it minimizes the temperature loss of the cold or hot air delivered by the air - conditioning system during transmission, greatly improving the energy efficiency of the air - conditioning system and reducing energy consumption.

Meanwhile, air duct aluminum foil also has good moisture - proof and anti - corrosion properties. During ventilation, condensation water is easily generated inside the air ducts due to temperature changes. The moisture - proof characteristic of aluminum foil can effectively prevent water from penetrating into the insulation layer inside the ducts, avoiding the insulation layer from reducing its insulation effect or even being damaged due to moisture. In addition, the surface of aluminum foil is smooth and not easily corroded by harmful substances in the air, which prolongs the service life of the air ducts.

In terms of construction, air duct aluminum foil also shows significant advantages. It is light in weight, easy to cut and install, and can adapt to air ducts of different shapes and sizes. This greatly improves the construction efficiency and shortens the construction period. Moreover, aluminum foil material is clean and hygienic, does not produce harmful substances, and meets the requirements of modern buildings for environmental protection and health.

Application Range

Air duct aluminum foil has a very wide range of applications. It can be seen in commercial buildings such as large shopping malls, office buildings and hotels, as well as in industrial and public facilities such as factories, hospitals and schools. Pure aluminum foil is suitable for ordinary office buildings, small shopping malls, etc. Composite aluminum foil is mostly used in hotel central air - conditioning systems and large factory workshop ventilation pipes because of its strong heat preservation. Embossed aluminum foil plays an important role in air duct elbows, interfaces and other easily deformed parts. It provides a reliable guarantee for the ventilation and air - conditioning systems of various buildings, ensuring the comfort and stability of the indoor environment.

In the U.S., over 76 million homes rely on central HVAC systems, making the duct system a critical part of the nation’s energy infrastructure. With an average home using 300 feet of air ducts, residential installations alone exceed 800,000 miles—enough to wrap around the Earth more than 32 times.

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Given this scale, choosing the right type of ducting is essential. It directly affects airflow efficiency, insulation value, labor costs, and the comfort of building occupants. While sheet metal and flexible ducts remain common, fiberglass duct board is gaining traction—especially in residential and light commercial settings—due to its built-in insulation, ease of installation, and cost-effectiveness.

This guide will examine what fiberglass duct board is, how it compares to traditional ducting, and where it fits best in modern HVAC applications.

Duct board provides continuous thermal insulation across all duct surfaces, minimizing thermal bridging and leakage. Most formulations meet or exceed ASTM E84 and NFPA 90A/90B standards, ensuring compliance with U.S. building codes for flame spread and smoke development. The non-metallic structure inherently reduces vibration noise, while the sealed, foil-lined exterior offers moisture and condensation resistance, especially in humid environments. Additionally, the lightweight design eases handling and reduces the need for structural support in ceiling installations.

Compared to traditional ducting, duct board systems are quieter, lighter, easier to install, and more thermally efficient—making them a preferred solution in residential and light commercial duct systems, where energy codes, installation labor, and indoor air quality are closely scrutinized by both contractors and building occupants.

Duct boards are manufactured in several structural configurations to meet different installation and durability needs. Some panels are single-sided, with one laminated surface—typically used when the duct is mounted flush against structural elements or walls. Others are double-faced, where both sides are factory-laminated for full vapor barrier protection and enhanced mechanical strength, particularly important for suspended or exposed ductwork. High-performance duct boards may also feature multi-layer composite facings, combining aluminum foil, woven fabric, and polymer coatings to meet stringent requirements for hygiene, durability, or chemical resistance.

In terms of fabrication, most duct boards are supplied in flat panel form and cut on-site using the score-and-fold method, allowing installers to shape and seal ducts quickly with minimal tools. This approach offers excellent adaptability to on-site conditions and irregular spaces. Alternatively, some systems—particularly those using PIR or phenolic cores—are designed for modular prefabrication, where duct sections are fabricated in a controlled environment with pre-formed elbows, transitions, and joints. These pre-engineered systems are especially advantageous in large commercial projects or fast-track construction timelines.

Proper installation is essential to duct board system performance and code compliance. Most assemblies—particularly those using fiberglass duct board or phenolic foam—are fabricated using the score-and-fold method. Panels are cut with grooving tools or slot cutters to create V-grooves, allowing clean folding without damaging the facing. Joints are sealed using UL 181-approved foil tape, mastic, or mechanical fasteners, depending on system pressure and project requirements.

Different core materials require tailored handling. Phenolic boards need precise scoring to avoid cracking, while MgO-based boards require dust control and carbide tools due to their density. Fiberglass cores are the most installer-friendly but still demand proper sealing, especially in humid environments. All seams, corners, and take-offs must be sealed tightly to ensure airtightness and energy efficiency, with vapor-barrier reinforcement recommended for rooftop or high-humidity areas.

Duct board is best suited for low to medium pressure systems (up to 2″ WG). For long runs or higher pressure zones, supports like hangers or saddles must be added at regular intervals. Installation should follow SMACNA’s guidelines for fibrous glass ducts for joint construction, reinforcement, and layout best practices.

Compared to sheet metal, duct board reduces labor and eliminates external insulation. It is ideal for retrofits, confined plenums, and projects where acoustic performance and installation speed are key. Common mistakes—like under-sealed corners or over-bent joints—can lead to leakage or structural failure and should be verified through pressure or smoke testing.

When installed correctly and in accordance with ASHRAE 90.1, IECC, and local codes, duct board systems offer reliable thermal insulation, air control, and indoor air quality performance.

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