Phenolic Foam Duct Insulation: Everything You Need to Know

Posted in: Ducting

Anyone who has ever dealt with insulating ducting will have heard of a variety of ways to do so. Examples include fibreglass, foam board, reflective/radiant barrier, spray foam and mineral wool insulation methods.

While each has its pros and cons, one method that emerges as a sound choice for a wide variety of applications is phenolic foam insulation.

In this comprehensive guide, you’ll discover the benefits and features of phenolic foam pipe insulation. From its thermal efficiency to fire safety, this article covers everything you need to know about using phenolic foam for effective and reliable insulation solutions.

What is phenolic foam?

Phenolic foam is an insulation material that is typically used in the construction and building services industry. It is known for its exceptional fire performance, low thermal conductivity, moisture resistance and structural strength.

What makes phenolic foam unique is that it has a closed cell structure that provides excellent thermal insulation. This makes it up to 50% more thermally efficient than other common insulation materials. It is also highly resistant to water vapour and has low water absorption.

Additionally, phenolic foam emits very low levels of smoke and toxic gases when exposed to fire, which enables it to meet various international fire safety standards.

What is phenolic foam made of?

Phenolic foam is made from phenolic resins, which are a type of synthetic polymer obtained by the reaction of phenol with formaldehyde. The foam is created by adding a foaming agent to the phenolic resin, which causes it to expand and form a rigid, closed-cell structure.

This structure is what gives phenolic foam its excellent thermal insulation properties as well as fire and moisture resistance.

What is phenolic foam used for?

Phenolic foam is used in a wide range of applications, including roofing, wall and floor insulation, duct supports and structural panels. As a highly versatile material, it can be used in:

Heating, ventilation and air conditioning (HVAC): In HVAC settings, the foam is cut to accurate tolerances on special computer-controlled cutting equipment with a variety of different parts available.
Pipe and duct supports: These typically use high-density foam for a variety of structural applications.
Building applications: Examples include roofing, cavity boards, external wall boards, plasterboard dry lining systems, wall and floor insulation and as a sarking board.
Factory engineered composite panels: These consist of a high-density structural phenolic foam core with steel facings on both sides alongside a jointing system. Examples of industries that use them include food processing factories, cold stores, semi-conductor clean rooms, hospitals, etc.
Process/petrochemical applications: Examples of usage include insulation of pipework, tanks, vessels, etc.
Other specialist applications: Walk-on ceilings, fire doors, highly fire-resistant panels, insulation in surface ships, off-shore installations and submarines, etc.

Therefore, it is highly suitable for a large range of applications where thermal performance, moisture resistance, fire performance and structural strength are key criteria.

What are the advantages of phenolic foam insulation?

Using phenolic foam insulation in your next project is a good idea because it offers a unique range of benefits. Among these include:

Strong thermal insulation to minimise heat loss or gain in HVAC systems to maintain energy efficiency and optimise temperature control in buildings.
Fire resistance in building applications due to a low flame spread index. It also generates less smoke, which makes it a safer choice for ducting in both commercial and residential properties.
Its lightweight nature makes it easier to handle and install, which makes construction processes simpler and its good density parameters ensure valuable space is saved.
It can also provide sound insulation by reducing noise transmitted through ducting systems, to ensure a quiet indoor environment.
Its moisture resistance helps prevent the growth and spread of mould and mildew in ducting systems, which is especially important in environments with high levels of humidity.
Phenolic foam is known for its structural strength/density relationship.
Phenolic foam is also recyclable, helping those with environmental concerns address such issues with more confidence.

What are the disadvantages of phenolic foam insulation?

Despite its significant advantages, a few of the downsides to phenolic foam insulation include the following:

It can be more expensive than other insulation materials, which may not suit those on tight project budgets.
It is somewhat more brittle than other insulation materials, which makes it susceptible to cracking or breaking under impact or during installation.
It may not be as readily available as other insulation types.
It has a small potential for toxicity as it involves the use of formaldehydes and other chemicals, which can be toxic. In turn, this requires following proper safety measures during installation.
If not properly sealed, it may absorb water under certain conditions.
It can lose its structural integrity at high temperatures.
It may require the use of skilled labour and careful handling during installation.

What is the difference between phenolic and PIR insulation?

Phenolic insulation and PIR (Polyisocyanurate) insulation are both popular materials used for thermal insulation in construction and industrial applications.

Here are the key differences between the two:

Composition

Phenolic foam insulation is made from phenolic resin, which is a thermosetting polymer. It is created through a chemical reaction between phenol and formaldehyde, resulting in a rigid foam structure. Meanwhile, PIR insulation is made from polyisocyanurate, which is a type of polyurethane foam. It is produced from the reaction of isocyanates and polyols, leading to a rigid foam with specific properties.

Thermal performance

Whereas phenolic foam generally offers a lower thermal conductivity (around 0.020-0.025 W/m·K), which provides excellent thermal insulation and makes it highly efficient for maintaining temperature, PIR insulation also has good thermal performance, with thermal conductivity values typically ranging from 0.022 to 0.028 W/m·K. Although PIR is effective, it is slightly less efficient than phenolic insulation in some cases.

Fire Resistance

Known for its high fire resistance, phenolic foam has a low flame spread index and generates minimal smoke when exposed to fire, making it a safer choice for many applications. However, although PIR has good fire-resistant properties, it is generally not as fire-resistant as phenolic foam. It may require additional fireproofing measures in certain applications.

Moisture resistance

In terms of moisture resistance, phenolic insulation is a sound choice as it is less prone to water absorption compared to some other materials. However, if not properly sealed, it can absorb moisture over time. PIR insulation also provides good moisture resistance, but it can absorb water if damaged or improperly installed. Its closed-cell structure helps to minimise moisture infiltration.

Weight and density

Typically denser and heavier than PIR, phenolic foam can make handling and installation more challenging. PIR insulation, on the other hand, is generally lighter and easier to handle, which can simplify installation processes.

Cost

With regard to cost, phenolic insulation is often more expensive than PIR insulation due to its specialised manufacturing process and superior thermal properties.

Environmental Impact

And lastly, with regard to environmental impact, phenolic insulation production involves chemicals that may have environmental impacts, and disposal can be more complicated due to its non-biodegradable nature. With PIR insulation, it also has environmental considerations, particularly in its production and disposal, but advancements in manufacturing processes are improving its sustainability.

Is phenolic foam waterproof?

While it has excellent water resistance, phenolic foam is not fully waterproof. However, it is worth noting that it has a lower water vapour permeance and low water absorption. It is also non-wicking, which means that any moisture ingress is limited to the affected area only thus avoiding compromising the entire system.

Is phenolic foam fireproof?

Phenolic foam is not entirely fireproof, but it is highly fire-resistant. It has a zero to very low flame spread with negligible smoke emission. It also has a low level of toxic gas emission. The phenolic foam insulation fire rating in the UK is Class O.

Is phenolic foam hazardous?

In some circumstances, phenolic foam can pose certain health and safety hazards, largely owing to the chemicals involved in its production and installation. A few important points to consider regarding its hazards include:

Chemical exposure during the manufacturing process
Exposure to dust, particulates and fumes during cutting or handling the foam
Requires proper ventilation in the work area to reduce exposure to any off-gassing
It requires following local regulations for proper disposal of the material
It can burn under certain conditions, releasing potentially harmful smoke and fumes

Overall, proper storage and handling are essential to minimise risks.

Conclusion

Using phenolic foam comes with many advantages that exceed the disadvantages. It is a highly versatile material that has multiple applications and its water and fire resistance make it a particularly sturdy and useful insulation material.

If you are looking for a variety of phenolic foam flat strips, here at Ducting Express you can find them in a variety of sizes including:

Don’t hesitate to browse our extensive selection and always count on our expert team to help you if you have any questions or need sound advice.