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Aluminum Foil As a Vapor Barrier

Aluminum Foil As a Vapor Barrier

Aug 2,2022
The question often arises whether a vapor retarder or vapor barrier is more suitable for renovation or new construction. Both of these alternatives can be used to seal insulated building components.

The advantage of a vapor barrier is that it won't let any moisture through so she's airtight.

On the other hand, when using a steam retarder, water vapor can escape in small amounts.

Standard deviation

In this context, people often talk about the SD value. The SD value is a diffusion-equivalent air layer thickness that represents the time it takes for water vapor to migrate through an airtight assembly. For example, if the value is 4m, this means that water vapor takes as long as it takes to pass through the airtight assembly by convection as it takes to pass through a 4 m thick layer of air. Vapor barriers typically have SD values in excess of 1,500m. All values below this value are within the range of steam retarders.

Aluminum foil is great for use as a vapor barrier to better protect the insulation from moisture penetration. For example, fiberglass insulation can be laminated with aluminum foil. This creates an optimal vapor barrier. Aluminum foil has been used as a moisture barrier since the 1970s.

How useful is it to use aluminum foil as a moisture barrier?

Aluminum foil for roof insulation

Even though aluminum foil ages faster than other materials, it makes sense to use aluminum foil. Vapor barriers can be produced inexpensively using aluminum foil. With aluminum foil, care should always be taken to ensure it is bonded over a large area.

Public swimming pools, saunas, and other wet areas are often sealed with aluminum foil. But aluminum foil should also be used for insulation on house roofs. The vapor barrier plays an important role here. It ensures that moist air does not get in

Vapor barrier made of aluminum foil

A moisture barrier made of aluminium foil should always be installed on the room side of the insulation. Otherwise, it won't work. To ensure foil is processed correctly, many foils have a label that must be pointed indoors during processing. One of the great advantages of high-quality aluminum foils as vapor barriers are that they are very durable and inexpensive.

Plastic and aluminum foil is the most commonly used vapor barriers of all materials. It is usually offered as a character. Conventional film rolls have a width of 1.50m. Many rolls are 50 or 100m in length. Aluminum foil is considered to be very durable, tear-resistant, and vapor-resistant. PE-aluminum laminated moisture barrier is particularly suitable for moisture-proof construction. Optimum thermal insulation is achieved if an aluminium foil vapor barrier is installed. This is 10% higher than without the foil.

What are the application scenarios of the steam control layer?

If a moisture barrier is not professionally installed, a lot of moisture damage can occur. This is mainly because structures with vapor barriers are difficult to seal with only aluminum foil. In most cases, however, it's not the foil that's to blame, but the craftsmanship.

If the foil is not applied correctly, the problem is usually in the joint area. However, in some cases, the membrane can also be damaged when connecting the socket. If you want to set up a moisture barrier in an attic, sauna, pool area, steam room, or cold room, you have to be very careful with aluminum foil.

It is also necessary to check in advance whether the insulation is still damp during installation. In this case, the insulation should not be allowed to dry until it is completely dry. Otherwise, the aluminum foil will prevent the water in the assembly from evaporating inside. Air-dried components also contain several liters of water per square meter due to the material's adsorption capacity. In this case, an expert should always be consulted before using aluminum foil as a vapor barrier. If everything is professionally laid, then aluminum foil can provide high quality.

These films are available in a variety of sizes and lengths and can be optimally adapted to any structure. Multilayer metalized films are particularly suitable. They reflect thermal energy and create an additional insulating effect.

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Simple processing

The biggest advantage of aluminum foil as a vapor barrier is that it is easy to process. It is very cheap compared to other materials. At the same time, the aluminium foil ensures increased thermal insulation in the presence of a vapor barrier.

Heat and radiation reflection

Aluminum foil vapor barrier shields up to 99% of electromagnetic radiation. In addition, it reflects 50% of the heat. A small disadvantage is that the foil must be laid down cleanly. Otherwise, they are not sealed.


You have to work very carefully as the foil will tear very quickly. However, once properly bonded, it provides the best vapor barrier. A moisture barrier made of aluminium foil can be used on all unventilated and ventilated roofs, i.e. cool and warm roofs. It is ideal for attic or facade-insulated apartments.

Many films are vapor resistant and also provide good wind protection. Using a vapor barrier can reduce your home's energy costs. A high-quality film prevents heat loss while protecting the insulation from moisture. Insulation mounted on the rafters is also very useful if needed. This is the case, for example, when the roof has been removed or is being renovated. The vapor control layer is then simply attached to the underside of the roof insulation.

The above describes the benefits of aluminum foil as a vapor barrier in detail, if you want to know more or want to buy aluminum foil, please contact us.

PENGYUAN is a professional custom aluminum foil manufacturer. Polarfoil supplies more than 360 million square meters (tons) annually to customers around the world. With wider and deeper cooperation, PENGYUAN will continue to focus on the development and manufacture of extrusion coating technology. We are committed to becoming an advanced energy-saving new material and solution provider.
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Learn more from our FAQ
Which to choose Aluminum foil coated PE or Metalized pet film coated PE ?

It depends on what product to be made in final procedure. Aluminum foil coated pe is with at least 97% reflectivity, it can be bonded to EPE foam but also most of time for laminated with bubble. Metalized pet film coated PE with lower reflectivity ,but it is with strong surface.

I am a insulated liner/bag manufacturer,what product do you suggest?

There maybe bubble lamination machines and heating pressure lamination machines in your factory, we suggest Aluminum foil 7mic+PE20mic, and Metalized PET film12mic+PE15mic.

If i would like to get a quote ,what information shall i need to know first?

You are request to telling application, material structure,thickness and roll width and quantity.

What is the MOQ and how is packaging?

MOQ is 1000kgs for each product, packaging depends on roll size, common width is 1200mm and 1500mm, length are 4000m to 5000m per roll. Rolls can be vertically packed on pallet also accept to do horizontal suspending packaging.

Is this product by wet lamination or by dry lamination?

Both wet lamination line(extrusion coating) and dry lamination line(glue coating) are equiped in our Pengyuan group.

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ZHEJIANG PENGYUAN is the leader of extrusion coating, the professional manufacturer & supplier of PolarFoil