What other insulation products should I consider?

Other polyester options include Fabufill; glasswool alternatives include Knauf and Aerolite.

Isotherm Insulation - 145mm / 135mm / 100mm / 75mm / 50mm

Q: Why is Isotherm no longer SABS approved?

Isotherm voluntarily withdrew SABS certification; while still safe and compliant with SANS standards, it no longer holds the SABS stamp.

Q: Is Isotherm fireproof?

Isotherm carries a B/B1/2 fire rating, making it non-combustible under normal residential conditions.

Q: How effective is Isotherm?

Isotherm delivers strong thermal and acoustic performance depending on thickness, offering year-round energy savings.

Q: What is Isotherm insulation made of?

Isotherm is made entirely from 100% recycled PET plastic bottles and is fully recyclable.

Isotherm Insulation – Polyester Ceiling Insulation

Isotherm insulation is a soft, non-irritant polyester ceiling insulation made from 100% recycled PET plastic bottles. Available in 40mm, 50mm, 75mm, 100mm, 135mm, and 145mm Isotherm thickness options, it provides an eco-friendly alternative to traditional insulation. Isotherm helps improve indoor comfort, reduce energy costs, and support healthier living environments, while remaining safe to handle and free from formaldehyde or chemical binders.

At Home Insulations, we supply and install Isotherm insulation across Johannesburg, Pretoria, Centurion, Cape Town, and Durban, with reliable delivery and professional installation services.

Isotherm Prices in South Africa – 2026 Cost Guide

Isotherm insulation prices vary depending on thickness and roll coverage. Thicker products such as 135mm and 145mm Isotherm cost more because of their higher R-values, while 40mm, 50mm, and 75mm options offer budget-friendly solutions for non-critical applications.

145mm Isotherm price – R699 per roll
135mm Isotherm price – R680 per roll
100mm Isotherm price – R599 per roll
75mm Isotherm price – R613 per roll
50mm Isotherm price – R516 per roll
40mm Isotherm price – R499 per roll

If you’re comparing Isotherm cost per m², each roll is labelled with coverage to help you calculate installation requirements accurately.

Which Isotherm Thickness Do You Need?

Use this simple guide:

145mm Isotherm – Cold climates (Johannesburg, Pretoria, Cape Town)
135mm Isotherm – Standard ceiling insulation for inland regions
100mm Isotherm – Warm climates (Durban, coastal areas)
75mm Isotherm – Internal walls and basic thermal applications
50mm Isotherm – Top-up insulation, between-floors, internal walls
40mm Isotherm – Light-duty insulation, DIY projects, partitions

Why Choose Isotherm Insulation?

Isotherm stands out in both environmental and functional performance:

Eco-Conscious – Crafted from 100% recycled PET bottles and fully recyclable
Safe & Skin-Friendly – Non-allergenic, non-irritant polyester feels like soft fabric
Thermal Efficiency – Typical R-values range from 0.82 to 3.37 depending on thickness
Moisture-Resistant – Absorbs less than 2% moisture and dries quickly
Fire Safety – Classified B/B1/2 under SANS – (B-class)
Low VOC & Chemical-Free – No added formaldehyde or harmful emissions
Maintenance-Free – Retains shape and loft for the life of your building
Easy to Handle – Lightweight rolls that are easy to cut and install without protective gear
Not SABS Approved – Lost its SABS approval rating

Where Can Isotherm Be Installed?

Residential homes
Townhouses and housing developments
Office ceilings
Light commercial buildings
Between floors for basic acoustic comfort
Retrofit and new construction projects

Isotherm insulation is a great fit for projects focused on comfort, sustainability, and health-conscious living. Its soft, non-irritant polyester fibres make it easy to install in spaces where traditional insulation for roofs might pose handling or skin sensitivity issues.

While not fire-rated for high-risk or regulated environments, Isotherm performs well in typical residential and low-demand commercial applications where natural materials and energy savings are key goals.

Thickness	R-value	Roll Length	Roll Width	Density	Climate Zone
145mm	3.37	5m	1.2m	11.5kg	Johannesburg
135mm	3.14	5m	1.2m	11.5kg	Johannesburg
100mm	2.33	6m	1.2m	10kg	Durban
75mm	1.53	8m	1.2m	10kg	Top Up Layer
50mm	1.02	10m	1.2m	10kg	Top Up Layer
40mm	0.82	10m	1.2m	10kg	Top Up Layer

145mm Isotherm Insulation

145mm Isotherm Insulation is the highest-performing polyester insulation in the Isotherm range and is best suited for colder South African regions such as Johannesburg, Pretoria, and Cape Town. With an R-value of 3.37, it delivers stronger thermal performance than the thinner Isotherm options, making it the top choice for homeowners wanting maximum warmth and improved energy efficiency.

Lightweight, non-irritant, and manufactured from 100% recycled PET plastic, 145mm Isotherm is easy to install and safe to handle without protective gear. While it is not SABS approved, it remains a popular eco-friendly ceiling insulation for homeowners prioritizing safety, comfort, and sustainability.

145mm Isotherm Specifications

Product: 145mm Isotherm Insulation
R-Value: 3.37
Roll Dimensions: 5m × 1.2m
Coverage: 6m² per roll
Density: 11.5kg/m³
Fire Rating: B/B1/2 (Polyester – not non-combustible)
Material: 100% recycled PET
Moisture Absorption: <2%
SABS Approved: No

Where 145mm Isotherm Works Best

Ceilings in cold inland regions
Pitched roofs and loft spaces
Homes needing higher thermal performance
Customers preferring non-irritant polyester insulation

For 145mm Isotherm price, installation, or delivery across South Africa, request a fast custom quote.

135mm Isotherm Insulation

135mm Isotherm Insulation is a high-performance polyester ceiling insulation designed for colder regions of South Africa, including Johannesburg, Pretoria, and Cape Town. With an R-value of 3.14, it provides dependable thermal resistance, helping homes stay warmer in winter and cooler in summer while reducing energy usage throughout the year.

Manufactured from 100% recycled PET plastic, this insulation is soft, non-irritant, and completely free from glass fibres or chemical binders. It’s ideal for homeowners who prefer a skin-safe, environmentally conscious product that’s easy to handle and install. While 135mm Isotherm is not SABS approved, it is suitable for general residential ceiling applications where polyester insulation is preferred.

135mm Isotherm Specifications

Product: 135mm Isotherm Insulation
R-Value: 3.14
Roll Size: 5m × 1.2m
Coverage: 6m² per roll
Weight: ±10.15kg
Material: Recycled polyester (PET)
Moisture Absorption: <2%
Fire Rating: B/B1/2 (Polyester classification)
SABS Approved: No
Handling: Soft, non-irritant, no protective gear required

Best Uses for 135mm Isotherm

Standard ceiling insulation for inland climates
Pitched roofs and attic spaces
Homes requiring improved thermal efficiency
Installations where a non-irritant, chemical-free product is preferred
Eco-conscious households seeking a sustainable insulation option

Choose 135mm Isotherm Insulation if you want an environmentally friendly product that delivers solid thermal performance without the itch or irritation of traditional fiberglass materials. Request a quote or place an order for fast installation and delivery across South Africa.

100mm Isotherm Insulation

100mm Isotherm Insulation is a medium-thickness polyester insulation ideal for warmer and coastal regions such as Durban, East London, Gqeberha, and other humid areas of South Africa. With an R-value of 2.33, this product offers reliable thermal performance for homes that do not require high levels of winter heating, helping to stabilise indoor temperatures and reduce cooling costs in summer.

Made from 100% recycled PET bottles, 100mm Isotherm is soft, non-irritant, and completely free from hazardous fibres or chemical binders. It is safe to handle, easy to install, and dries quickly if exposed to moisture. While not SABS approved, this thickness is suitable for standard residential applications in mild climates.

100mm Isotherm Specifications

Product: 100mm Isotherm Insulation
R-Value: 2.33
Roll Size: 6m × 1.2m
Coverage: 7.2m² per roll
Weight: ±10kg
Material: Recycled polyester (PET)
Moisture Absorption: <2%
Fire Rating: B/B1/2 (Polyester classification)
SABS Approved: No
Handling: Non-irritant, safe to install without gloves or masks

Best Uses for 100mm Isotherm

Ceilings in moderate and coastal climates
Homes focusing on summer cooling efficiency
Retrofit upgrades where thicker insulation won’t fit
Installations requiring a soft, non-irritant material
Eco-friendly households preferring recycled materials

Choose 100mm Isotherm Insulation for dependable thermal comfort in warmer regions. It’s lightweight, safe to install, and delivers long-term energy savings without the irritation of fiberglass insulation. Contact us for pricing, installation options, or fast delivery anywhere in South Africa.

75mm Isotherm Insulation

75mm Isotherm Insulation is a lightweight polyester insulation designed for applications where moderate thermal performance is required. With an R-value of 1.53, it is ideal for internal walls, between-floor sound insulation, mild climates, or as a top-up layer over older insulation. This thickness is not intended for primary ceiling insulation in colder regions but serves well in non-critical areas where comfort and noise reduction are the main goals.

Made from 100% recycled PET plastic, 75mm Isotherm is soft, non-irritant, and completely free of fiberglass or chemical binders. It installs easily without protective clothing and provides a clean, eco-friendly option for homeowners wanting a safer alternative to traditional insulation. Please note that this thickness is not SABS approved and not SANS compliant for regulated ceiling installations.

75mm Isotherm Specifications

Product: 75mm Isotherm Insulation
Material: Recycled polyester (PET)
R-Value: 1.53
Roll Length: 8,000mm
Roll Width: 1,200mm
Coverage: 9.6m² per roll
Weight: ±7.85kg
Moisture Absorption: <2%
Fire Rating: B/B1/2 (Polyester classification)
SABS Approved: No
SANS Compliant: No
Handling: Soft, non-irritant, safe to install by hand

Best Uses for 75mm Isotherm

Internal partition walls
Sound insulation between floors
Mild climates requiring minimal thermal resistance
DIY projects and renovations
Top-up insulation over old ceiling insulation
Projects prioritizing skin-safe, chemical-free materials

Choose 75mm Isotherm Insulation for light-duty thermal performance, added acoustic comfort, and eco-friendly materials. It’s perfect for spaces where a full-compliance ceiling insulation is not required. Contact us for pricing, delivery, or installation across South Africa.

50mm Isotherm Insulation

50mm Isotherm Insulation is a light-duty polyester insulation ideal for internal walls, between-floor sound absorption, ceiling overlays, and other non-critical thermal applications. With an R-value of 1.02, this thickness provides basic insulation performance, making it suitable for projects where moderate comfort improvement is needed but full SANS compliance is not required.

Manufactured from 100% recycled PET plastic, 50mm Isotherm is soft, flexible, and completely free from glass fibres or added chemicals. It is safe to handle without gloves or masks, making it a popular choice for DIY installations, renovations, and homes prioritising eco-friendly, non-irritant materials. Please note that this thickness is not SABS approved and not SANS compliant for regulated ceiling installations.

50mm Isotherm Specifications

Product: 50mm Isotherm Insulation
Material: Recycled polyester (PET)
Thickness: 50mm
R-Value: 1.02
Roll Length: 10,000mm
Roll Width: 1,200mm
Coverage: 12m² per roll
Weight: ±6.55kg
Moisture Absorption: <2%
Fire Rating: B/B1/2 (Polyester classification)
SABS Approved: No
SANS Compliant: No
Handling: Non-irritant, safe to install by hand

Best Uses for 50mm Isotherm

Top-up insulation over existing ceiling insulation
Internal partition walls
Between floors for moderate sound control
DIY home improvements and retrofit upgrades
Areas with limited roof height or tight installation spaces
Projects prioritising soft, skin-safe, eco-friendly insulation

Choose 50mm Isotherm Insulation for affordable, environmentally friendly comfort enhancements in non-critical spaces. Order online or request a free quote for delivery and professional installation anywhere in South Africa.

40mm Isotherm Insulation

40mm Isotherm Insulation is the thinnest and most flexible option in the Isotherm polyester range, ideal for interior partitioning, ceiling overlays, between-floor applications, and other non-critical insulation tasks. With an R-value of 0.82, it provides minimal thermal resistance, making it best suited for projects where the goal is improved comfort, basic heat reduction, or acoustic softening rather than full compliance with building regulations.

Manufactured from 100% recycled PET, 40mm Isotherm is soft, lightweight, and completely non-irritant, offering a clean, chemical-free alternative to traditional insulation. This thickness is easy to cut, shape, and install, making it popular for DIY upgrades, home renovations, and interior spaces where only a light insulation layer is required. Please note that 40mm Isotherm is not SABS approved and not SANS compliant, and should not be used as primary ceiling insulation in regulated environments.

40mm Isotherm Specifications

Product: 40mm Isotherm Insulation
Material: Recycled polyester (PET)
Thickness: 40mm
R-Value: 0.82
Roll Length: 10,000mm
Roll Width: 1,200mm
Coverage: 12m² per roll
Weight: ±5.35kg
Moisture Absorption: <2%
Fire Rating: B/B1/2 (Polyester classification)
SABS Approved: No
SANS Compliant: No
Handling: Soft, safe to install without protective gear

Best Uses for 40mm Isotherm

Light-duty thermal applications
Interior partition walls
Between floors for mild acoustic improvement
Ceiling overlays in non-critical areas
DIY home renovation projects
Spaces requiring a soft, skin-safe, recyclable insulation alternative

Choose 40mm Isotherm Insulation for simple, affordable comfort upgrades in internal or unregulated spaces. Contact us for pricing, delivery, or professional installation across South Africa.

Thermal Insulation cost for homes and buildings

Related Insulation Pages

Polyester Insulation – Explore similar insulation materials.
Ceiling Insulation – See how this product is used in real homes.
Isotherm vs Aerolite – Compare performance, pricing, and fire ratings.
Isotherm vs Knauf – See how two leading ceiling insulation products differ.
Isotherm vs Fabufill – Compare polyester vs glasswool insulation.
Materials – Explore insulation by material type.
Applications – See which insulation suits each part of your home.
Comparisons – View insulation materials side by side.
Insulation – Full breakdown of insulation types and uses.
Guides – Expert advice for installation and maintenance.

Frequently Asked Questions

Why is Isotherm no longer SABS approved?

Isotherm insulation no longer holds SABS approval because it failed to meet updated requirements set out by the South African Bureau of Standards. While it was previously certified, changes in either product composition, manufacturing standards, or testing compliance resulted in the loss of its SABS certification.

This means Isotherm does not meet the official criteria for safety, quality, or performance as defined by the SABS. For projects that require SABS-approved materials — such as government tenders or large-scale developments — alternative products like Aerolite or Knauf should be considered.

Is Isotherm fireproof?

No, Isotherm is not fireproof. It carries a B/B1/2 (B-class) fire rating under SANS standards, which means it is combustible but self-extinguishing. While it will not cause flames to spread rapidly, it can catch fire if exposed to direct flame or high heat. For applications requiring non-combustible insulation, consider alternatives like Aerolite or Knauf, which carry an A1 fire rating and are fully fire-resistant.

How effective is Isotherm?

Isotherm insulation is effective for general thermal performance, especially in residential ceilings and internal walls. However, it does not match the performance levels of glasswool products like Knauf or Aerolite, which offer higher R-values per millimeter, better fire resistance, and greater overall energy efficiency and soundproofing.

While Isotherm is a good option for eco-conscious buyers looking for a non-irritant, polyester-based product, it may not be the best choice for cold climates or areas where maximum insulation performance is needed.

What is Isotherm insulation made of?

Isotherm insulation is made from 100% recycled PET plastic, the same type of plastic used in water and cooldrink bottles. The plastic is melted down and spun into soft polyester fibres, creating a non-toxic, non-irritant insulation material.

Isotherm Insulation