When transporting hot gases with a temperature of more than 100 °C in ventilation systems, the thickness of the steel walls of the air ducts should be 1–2 mm. To transport air with an admixture of toxic gases and vapors, air ducts must be made of certain materials, depending on the composition of the gases (steel with a thickness of at least 0.7 mm, aluminum, vinyl, etc.).

In ventilation systems of residential, public and administrative buildings, as well as office and auxiliary premises of industrial enterprises, air ducts made of slag-alabaster, cinder-concrete, reinforced cement and plastic plates, bricks, concrete, etc

. are used for portable ventilation installations rubberized, as well as metal flexible hoses.

When laying rectangular vertical air ducts, they try to make the most of the internal walls, in which appropriate channels are left for this purpose. If this is not possible, side channels and shafts are mounted to the walls.

In addition, spiral-wound metal air ducts are used in construction practice, as well as plastic air ducts that resist corrosion (made of vinyl, polyisobutylene, etc.). Their disadvantage lies in the fact that they can only be used at a temperature of transported air no higher than 70 °C.

In addition to these modifications, the ducts can be flexible, semi-flexible, thermally insulated, and also acting as a muffler.

Most often, metal ducts are used in air conditioning systems, which have great strength and resistance to fire.

They are made of galvanized or stainless steel.

Spiral-lock round (with a folding connection). They are made of steel tape with an anti-corrosion coating 0.5–1 mm thick, about 130 mm wide. They have increased rigidity compared to straight-seam ducts, there is no length restriction, aesthetic appearance, high seam density. The disadvantages include the fact that the seam takes about 15% of the metal from which the duct is made.

Spiral-welded round. They are made of steel tape with an anti-corrosion coating 0.8–2.2 mm thick, about 400–750 mm wide. The joints are welded overlap. Spiral-wound air ducts have less metal consumption compared to spiral-lock air ducts, there is no length restriction, high seam density. However, they cannot be made from steel thinner than 0.8 mm.

Rectangular straight-folding air ducts. They are made of steel sheet, it is desirable to place the seam on the bend so that it serves as an additional stiffener. Such ducts are easier than round ones to place in a space with a limited height, they fit better into the interior of the building. Rectangular ducts have greater aerodynamic drag than circular ducts with similar performance.

Round straight-folding air ducts. According to the manufacturing method and material, they are similar to rectangular air ducts, they differ only in a circular cross section.

Metal-plastic air ducts consist of two layers of metal, between which foam plastic is laid. Usually such a construction is used: foamed plastic 2 cm thick, located between layers of corrugated aluminum 80 microns thick. They have a small mass with high strength. They have a smooth surface, aesthetic appearance, do not require additional thermal insulation.

Non-metallic air ducts are made of synthetic materials: polyethylene, fiberglass, etc.

Polyethylene air ducts: are usually used in supply ventilation systems. When the fan is turned on, the duct (in the form of a sleeve) is inflated with air.