Isotherm Insulation South Africa – Prices, Sizes & Installation

If you are looking for Isotherm Insulation in South Africa, choosing the correct thickness is one of the most important decisions you can make for your home or commercial building. Isotherm is a polyester ceiling insulation manufactured from recycled PET plastic bottles and is designed to improve indoor comfort by reducing heat transfer through the roof.

At Roof Insulation, we have more than 36 years of insulation experience, supplying and installing insulation throughout South Africa. Whether you need 145mm, 135mm, 100mm, 75mm or 50mm Isotherm insulation, we can help you choose the correct product for your application.

Unlike fibreglass insulation, Isotherm is manufactured from polyester fibres, making it comfortable to handle during installation while providing dependable thermal insulation for residential and commercial buildings.

What is Isotherm Insulation?

Isotherm is a polyester ceiling insulation manufactured from recycled plastic bottles. Instead of using glass fibres, the insulation consists of thousands of bonded polyester fibres that trap air and reduce the movement of heat through the ceiling.

The result is a ceiling insulation product that helps keep homes warmer during winter and cooler during summer while contributing towards lower energy consumption.

Isotherm is widely used in:

• Residential homes
• Townhouses
• Schools
• Offices
• Commercial buildings
• Government buildings
• New developments
• Renovation projects

 

 

Why Choose Isotherm Insulation?

Many customers choose Isotherm because of its unique polyester construction.

Benefits include:

✔ Manufactured from recycled PET plastic bottles

✔ Non-irritating during installation

✔ No loose glass fibres

✔ Excellent thermal insulation

✔ Lightweight

✔ Long service life

✔ Will not rot under normal conditions

✔ Environmentally responsible manufacturing

✔ Suitable for most residential ceiling applications

Available Isotherm Thicknesses

Your Isotherm insulation requirements will depend on your climate, roof construction and insulation objectives.

145mm Isotherm

The highest thermal performance available within the Isotherm range and recommended where maximum energy efficiency is required.

Suitable for:

• Premium homes
• New energy-efficient buildings
• Areas with very hot summers
• Colder inland regions

 

135mm Isotherm

One of the most popular residential options, offering excellent thermal performance while remaining cost effective.

Suitable for:

• Residential homes
• Renovations
• Offices
• New housing developments

 

100mm Isotherm

An economical option for improving ceiling insulation where moderate thermal performance is required.

Suitable for:

• Existing homes
• Offices
• Rental properties

 

75mm Isotherm

Ideal where roof cavity height is limited or budgets are restricted.

Suitable for:

• Garages
• Small extensions
• Budget projects

 

50mm Isotherm

The entry-level option within the range.

Suitable for:

• Limited insulation upgrades
• Mild climate areas
• Smaller applications

 

 

 

Which Thickness Should You Buy?

As insulation specialists, our recommendation is simple.

If your budget allows, we generally recommend selecting the highest practical R-value for your ceiling.

Technical Specifications

Typical product characteristics include:

• Polyester insulation
• Manufactured from recycled PET bottles
• Fire Rating: B/B1/2
• Lightweight construction
• Good thermal performance
• Long service life
• Resistant to normal ageing
• Easy to cut and install

Unlike fibreglass insulation products such as Knauf and Aerolite, Isotherm does not achieve a Class A/A fire rating and generally provides lower acoustic absorption (NRC). Customers whose priority is maximum fire performance or sound reduction should compare Isotherm with those alternatives before making a decision.

Fire Performance

One of the most common questions we receive concerns fire safety.

Isotherm has a B/B1/2 fire rating, which differs from the Class A/A fire rating achieved by certain fibreglass insulation products.

This does not mean Isotherm is unsuitable for residential ceilings, but if maximum fire resistance is your primary requirement, products such as Knauf Insulation or Aerolite may be a better choice.

Our approach is always to recommend the product that best suits the customer’s requirements rather than promoting one insulation type for every project.

Acoustic Performance

Isotherm provides some sound reduction, but its Noise Reduction Coefficient (NRC) is generally lower than high-performance fibreglass insulation.

If your main objective is:

• Home theatre sound reduction
• Office acoustics
• Recording studios
• Maximum noise control

then dedicated acoustic insulation or higher-density fibreglass products may provide better performance.

Isotherm vs Knauf Insulation

Both products have their place, depending on the customer’s priorities.

Isotherm vs Aerolite

Aerolite and Knauf remain one of South Africa’s most recognised fibreglass insulation brands and offers excellent fire and acoustic performance.

Isotherm is often selected by customers looking for a polyester insulation manufactured from recycled materials.

Our experienced team can help you compare both products before making a purchase.

Installation Advice

Correct installation is just as important as selecting the correct insulation.

Poorly installed insulation can leave gaps that reduce thermal performance.

Our installation team has more than 36 years of practical insulation experience, and we recommend:

• Installing insulation without compression.
• Covering the entire ceiling area.
• Avoiding gaps around services.
• Cutting neatly around roof trusses.
• Maintaining full thickness throughout the installation.

Professional installation helps ensure you achieve the full thermal benefit of your chosen insulation.

Technical Specifications Table

This is one of the first things buyers look for.

We’ll complete the official R-values once we have them.

Why Buy From Roof Insulation?

This helps conversions as well as EEAT (Experience, Expertise, Authoritativeness and Trustworthiness).

Why Buy Isotherm Insulation From Roof Insulation?

When purchasing ceiling insulation, choosing the right supplier is just as important as selecting the correct product.

With more than 36 years of practical insulation experience, we supply quality insulation products throughout South Africa while helping customers choose the most suitable solution for their application and budget.

Why customers choose us

• Over 36 years of insulation experience
• Expert technical advice
• Competitive pricing
• Fast nationwide delivery
• Professional installation available
• Assistance choosing the correct thickness
• Quality products from trusted manufacturers
• Friendly after-sales support

 

 

Comparison Table

Google loves comparison content because it’s genuinely useful.

This is balanced and fact-based.

Need Help Choosing the Right Isotherm Insulation?

Not sure whether you need 145mm, 135mm, 100mm, 75mm or 50mm Isotherm insulation?

Our experienced insulation specialists can recommend the correct thickness based on your location, roof design and energy-saving goals.

✔ Free product advice

✔ Fast quotations

✔ Nationwide delivery

✔ Professional installation available

Request a Quote today or contact us for expert assistance.

Frequently Asked Questions

Is Isotherm made from recycled plastic bottles?

Yes. Isotherm is manufactured from recycled PET plastic bottles.

Does Isotherm itch like fibreglass?

No. Polyester insulation is generally more comfortable to handle during installation.

Which thickness is best?

For most homes, 135mm or 145mm provides the best thermal performance.

Can Isotherm be installed in existing homes?

Yes. It can be installed in both new and existing residential ceilings.

Is Isotherm waterproof?

It should be kept dry in service. As with any ceiling insulation, roof leaks should be repaired promptly to maintain performance.

How long does Isotherm last?

When installed correctly and protected from moisture, it is designed to provide many years of thermal performance.

Can I install it myself?

Yes, but professional installation generally produces better coverage and avoids gaps that reduce effectiveness.