Aerolite vs Isotherm product comparison in south africa

Aerolite vs Isotherm: A Comprehensive Comparison

When comparing Aerolite vs Isotherm, it’s essential to look at key factors like thermal performance (R-value), density, fire safety, noise control, and cost.

Both products are popular ceiling insulation options in South Africa — but Aerolite consistently outperforms Isotherm for thermal resistance, fire resistance, noise dampening, and price, while Isotherm stands out for its itch-free properties.

Aerolite vs Isotherm Comparison Table

Feature	Aerolite	Isotherm
Thermal Performance	★★★★★	★★★★☆
Noise Control	★★★★★	★★★☆☆
Fire Safety	★★★★★ (A1 rating)	★★★☆☆ (B-class)
Density	★★★★★	★★★☆☆
Non-itch	★★☆☆☆	★★★★★
Eco-Friendliness	★★★★☆	★★★★☆
Typical Lifespan	30–50+ years	30–40 years
Cost Efficiency	★★★★★ (more budget-friendly)	★★★☆☆ (higher price)

Thermal Performance: R-Value Comparison

One of the most important measures of insulation is its R-value, indicating how well it resists heat flow.

Aerolite insulation, made from glasswool, offers a higher R-value than Isotherm, meaning you get better thermal performance with less thickness. Your home stays warmer in winter and cooler in summer, reducing the load on your heating and cooling systems.
Isotherm insulation, made from thermally bonded polyester, also provides effective insulation but generally requires thicker material to match Aerolite’s thermal resistance.

Explore our full range of glasswool insulation and polyester insulation products to find the perfect solution for your home.

Density and Effectiveness

While Aerolite and Isotherm can have similar thicknesses, Aerolite is heavier by weight and has a much denser internal structure. Made from millions of tightly packed glass fibers, Aerolite’s mass allows it to trap more air, block heat flow more effectively, and absorb sound waves far better.

Isotherm, on the other hand, is made from larger, soft polyester fibers. This makes it lighter by weight and less dense overall, which means it doesn’t slow down heat or noise as effectively as Aerolite. However, its non-itch during installation, stays resilient, and maintains shape over time.

Fire Safety Ratings

Fire safety is crucial for any building material.

Aerolite carries an A1 fire rating, making it non-combustible. It doesn’t contribute to the spread of flames, giving you peace of mind in high-risk areas.
Isotherm holds a B-class rating, meaning it’s somewhat flame-retardant but not completely non-combustible. If fire resistance is a top concern, Aerolite is clearly the safer choice.

Learn more about fire ratings →

Soundproofing and Noise Control

Aerolite’s higher density also makes it significantly more effective at reducing noise. It absorbs sound waves and keeps rooms quieter — ideal if you live near busy roads or have a tiled roof that amplifies rain noise.

Isotherm, being a lightweight polyester, provides basic acoustic insulation but allows a lot more sound to pass through.

Learn more about soundproofing →

Price Comparison

Despite Aerolite’s superior thermal, acoustic, and fire safety ratings, it often comes in at a lower price point than Isotherm.

Aerolite’s glasswool manufacturing process is more cost-effective, giving you better performance at a lower cost per m².
Isotherm tends to be more expensive, even though it offers lower R-values and density. If you’re after maximum value for money, Aerolite is usually the clear winner.

SABS Approval Rating

When it comes to local approvals, Aerolite remains fully SABS approved, meeting strict South African standards for safety, thermal performance and fire compliance.

Isotherm, however, has lost its SABS certification, which raises concerns about whether it still meets all local compliance benchmarks. For many homeowners, this makes Aerolite the more trusted choice, backed by both proven performance and current approval from South Africa’s Bureau of Standards.

Which Insulation is More Eco-Friendly?

Both Aerolite and Isotherm are eco-friendly:

Aerolite is made from recycled glass and sand, helping reduce waste while delivering exceptional insulation.
Isotherm is manufactured from recycled PET plastic bottles, diverting plastic waste from landfills.

Either way, you’re making a sustainable choice.

Which Product is Easier to Install?

Isotherm is loved by installers for being itch-free during installation, making it comfortable to handle. However, it’s often harder to cut to precise sizes, which can slow down installation.

Aerolite, like most glasswool, can be slightly itchy (protective gear recommended) — but it’s much easier to cut and fit around trusses, pipes, and downlights. This often results in a faster installation.

Aerolite vs Isotherm: Final Verdict

If you’re looking for higher thermal resistance, better noise control, top fire safety and a lower price, Aerolite comes out ahead for South African homes.

If itch-free handling is your top priority — Isotherm is still a solid, eco-friendly choice.

Get Expert Help Choosing Between Aerolite and Isotherm

Still unsure which insulation suits your ceilings best? We supply and install both Aerolite and Isotherm across Johannesburg, Pretoria, Cape Town, and Durban.