Aerolite vs Isotherm Insulation

Aerolite vs Isotherm – Understanding The Differences

When South African homeowners start researching ceiling insulation, one comparison appears repeatedly: Aerolite versus Isotherm.

Both products are widely used throughout South Africa and both help reduce heat transfer, improve comfort and lower electricity consumption. However, they are manufactured from completely different materials and each has its own advantages.

Aerolite is manufactured from glasswool, while Isotherm is manufactured from polyester fibres.

The question is not which product is “good” and which product is “bad.” Both products perform well when correctly installed. The real question is which insulation product best suits your home, budget and personal preferences.

What Is Aerolite Insulation?

Aerolite Roof insulation is one of South Africa’s most established insulation brands.

Manufactured from glasswool, it has been installed in homes, offices, schools and commercial buildings for decades.

Aerolite is known for:

Many contractors and architects continue to specify Aerolite because of its extensive track record.

What Is Isotherm Insulation?

Isotherm is a polyester insulation product developed specifically for South African conditions.

Unlike traditional glasswool insulation, Isotherm contains no glass fibres.

Key characteristics include:

These features have made Isotherm particularly popular among homeowners seeking a polyester insulation solution.

Aerolite vs Isotherm At A Glance

FeatureAeroliteIsotherm
MaterialGlasswoolPolyester
Thermal PerformanceExcellentExcellent
Acoustic PerformanceExcellentGood to Excellent
Fire PerformanceExcellentGood
Moisture ResistanceGoodVery Good
Fibre-FreeNoYes
Dust-FreeNoYes
Residential UseYesYes
Commercial UseYesYes

Thermal Performance Comparison

The primary purpose of ceiling insulation is to reduce heat transfer.

Both Aerolite and Isotherm provide excellent thermal resistance and can significantly improve indoor comfort.

Benefits include:

For most homeowners, the thickness selected has a greater impact on performance than the brand selected.

Available Thicknesses

Aerolite

ThicknessRoll Size
50mm10m x 1.2m
100mm6m x 1.2m
135mm5m x 1.2m

Isotherm

Thickness
50mm
75mm
100mm
135mm
145mm

Isotherm offers a wider range of thickness options, including 145mm for homeowners seeking maximum thermal performance.

Acoustic Performance Comparison

One of the biggest secondary benefits of ceiling insulation is noise reduction.

Both products help absorb airborne sound and improve room acoustics.

Applications include:

Aerolite generally enjoys a slight advantage in acoustic absorption due to the structure of glasswool fibres, although both products perform well in residential applications.

Fire Performance Comparison

Fire performance is often overlooked when selecting insulation.

Aerolite is manufactured from glasswool and offers excellent fire resistance.

Isotherm roof insulation provides good fire performance but, as with all insulation products, should always be installed according to manufacturer specifications and local building regulations.

For applications where fire performance is a primary consideration, many professionals continue to favour glasswool insulation products.

Moisture Resistance Comparison

Moisture can affect the long-term performance of any insulation system.

Aerolite

Isotherm

For coastal applications, moisture resistance is often considered one of Isotherm’s strengths.

Installation Comparison

One of the biggest differences between the two products is handling.

Aerolite

Advantages:

Considerations:

Isotherm

Advantages:

Many homeowners choose Isotherm specifically because of its polyester construction and ease of handling.

Lifespan Comparison

Both products are designed to provide many years of service when correctly installed.

Key factors affecting lifespan include:

When protected from moisture and physical damage, both products can perform effectively for decades.

Which Product Offers Better Value?

The answer depends on your priorities.

Choose Aerolite If:

Choose Isotherm If:

Best Applications For Aerolite

Aerolite is ideal for:

Best Applications For Isotherm

Isotherm is ideal for:

Frequently Asked Questions

Is Isotherm Better Than Aerolite?

Neither product is universally better. Each has advantages depending on the application and homeowner preferences.

Which Insulation Lasts Longer?

Both products can provide decades of effective thermal performance when correctly installed.

Is Isotherm Warmer Than Aerolite?

Thermal performance depends largely on thickness and R-value rather than brand.

Which Product Is Better For Soundproofing?

Aerolite Insulation generally provides slightly stronger acoustic performance, although both products help reduce sound transmission.

Which Product Is Better For Coastal Areas?

Both products are widely used in coastal regions, although Isotherm’s moisture-resistant polyester construction is often viewed as an advantage.

Final Verdict – Aerolite vs Isotherm

Aerolite and Isotherm are two of South Africa’s leading insulation products.

Choose Aerolite For:

Choose Isotherm For:

For most homeowners, both products will deliver excellent thermal performance when the correct thickness is selected.

The best insulation is the one that matches your budget, performance expectations and personal preferences while being installed correctly.