There are many types of insulation available in South Africa, but they are not all designed for the same purpose.
Some insulation products are made primarily to reduce heat transfer through residential ceilings. Others are designed for thermal ceilings, cavity walls, acoustic applications, metal buildings or high-temperature industrial environments.
Choosing between the different types of insulation therefore requires more than comparing the price of one roll with another.
You need to consider the insulation material, thickness, R-value, intended application, fire performance, moisture resistance, acoustic properties and how the product will actually be installed.
For residential roof spaces, the most commonly considered types of insulation include glass wool, glass mineral wool and polyester insulation. Rigid XPS insulation boards are widely used where the insulation forms part of a finished ceiling system, while reflective foils have different applications within roofs and building envelopes.
Industrial and acoustic insulation products form another important group.
This guide explains the main types of insulation in South Africa, where each type is normally used and what you should consider before deciding which insulation is best for your home or building.
What Are the Main Types of Insulation?
The main types of insulation used in South African residential, commercial and industrial buildings can broadly be divided into:
- Glass wool insulation
- Glass mineral wool insulation
- Polyester insulation
- Extruded polystyrene or XPS insulation
- Mineral wool and acoustic insulation
- Reflective foil insulation
- Industrial glass wool insulation
- High-density industrial insulation
- Cavity insulation
There are also other insulation materials available internationally and in specialist South African applications, including cellulose, spray foam and various rigid insulation products.
However, not every insulation type is equally suitable for every roof or ceiling.
The important question is therefore not simply:
What are the different types of insulation?
It should be:
Which insulation type is best suited to this particular building and application?
1. Glass Wool Insulation
Glass wool is one of the most established types of insulation used in South African homes.
It consists of fine glass fibres formed into a lightweight insulation blanket or roll. The structure of the material traps air, creating resistance to heat transfer.
Two of the best-known residential products in this category are Aerolite and Knauf glass mineral wool insulation.
Glass wool is especially well suited to ceiling cavities because it can be cut to accommodate irregular timber spacing and roof structures.
Typical applications include:
- Residential ceiling insulation
- Roof insulation
- Timber roof spaces
- Retrofitting existing homes
- Thermal insulation
- Acoustic improvement
One of the main advantages of flexible glass wool is that installers can cut sections according to the actual spacing within the roof.
This is particularly useful in older South African homes where beam spacing is often not perfectly uniform.
Aerolite Insulation
Aerolite is one of South Africa’s best-known glass wool insulation products.
It is commonly installed above residential ceilings and is available in several thicknesses.
Popular residential options include:
- 50 mm
- 100 mm
- 135 mm
For residential roof insulation, the thicker products normally provide considerably stronger thermal resistance than thinner products.
Aerolite is flexible, lightweight and easy to cut, making it suitable for complicated roof structures.
When comparing types of insulation, Aerolite remains popular because it combines established thermal performance with relatively straightforward installation.
Correct installation is important.
Large gaps, excessive compression and areas left completely uncovered can reduce the performance of any bulk insulation product regardless of the quality of the insulation itself.
2. Glass Mineral Wool Insulation
Glass mineral wool belongs to the same broad insulation family as glass wool, but modern products can differ considerably in their binder technology, handling characteristics and specifications.
Knauf Insulation is a major example.
Knauf glass mineral wool manufactured using ECOSE Technology is widely used for thermal and acoustic applications.
Available products include several thicknesses suitable for residential ceilings as well as more specialised acoustic products.
When comparing residential types of insulation, Knauf and Aerolite frequently appear together because both are mineral-fibre-based flexible insulation systems.
The correct comparison should be made using:
- Product thickness
- Declared R-value
- Coverage per roll
- Cost per square metre
- Acoustic performance where relevant
- Fire performance
- Installation requirements
Do not compare insulation simply according to the selling price of an individual roll.
Roll dimensions and coverage can differ.
Where Glass Mineral Wool Works Well
Glass mineral wool is particularly suitable for:
- Ceiling insulation
- Timber roof structures
- Acoustic ceilings
- Internal partitioning
- Retrofit insulation
- New residential construction
- Commercial buildings
Because it can perform both a thermal and acoustic role, glass mineral wool is one of the more versatile types of insulation available.
3. Polyester Insulation
Polyester insulation is another commonly recognised ceiling-insulation material in South Africa.
Isotherm is the best-known example in this market.
Polyester insulation differs from glass wool because the blanket is manufactured from polyester fibres.
It is generally soft to handle and is often chosen by homeowners who prefer this type of material.
Typical thicknesses can include:
- 50 mm
- 75 mm
- 100 mm
- 135 mm
- 145 mm
Exact specifications should always be checked against the product being purchased.
Advantages of Polyester Insulation
Potential advantages include:
- Soft handling characteristics
- Flexible installation
- Can be cut for irregular roof spaces
- Thermal insulation
- Some acoustic benefit
- Suitable for residential ceilings
Like other bulk types of insulation, polyester relies heavily on correct thickness and good installation.
A poorly fitted polyester blanket with large gaps will not perform simply because it is a recognised insulation product.
Polyester vs Glass Wool Insulation
This is one of the most common insulation comparisons made by South African homeowners.
Neither material should be judged purely on whether it feels softer or whether one roll looks thicker than another.
Compare:
- Declared R-value
- Actual thickness
- Installed coverage
- Cost per square metre
- Fire classification
- Acoustic performance
- Product consistency
- Application
- Installation quality
For many customers, the decision eventually comes down to comparing Aerolite, Knauf and Isotherm.
These are three of the most familiar residential types of insulation, but their construction and specifications differ.
4. XPS Rigid Board Insulation
Extruded polystyrene, usually referred to as XPS, is quite different from flexible ceiling insulation.
XPS is a rigid closed-cell insulation board.
Products such as Isoboard and Summit XPS can form both the insulation layer and the visible finished ceiling.
This makes XPS one of the most useful types of insulation where homeowners want a thermal ceiling rather than insulation hidden above conventional ceiling boards.
Where XPS Insulation Is Used
Common applications include:
- Exposed-beam ceilings
- New thermal ceilings
- Garages
- Patios
- Entertainment areas
- Residential homes
- Selected commercial applications
- Areas where insulation and ceiling finish are combined
XPS boards are available in various thicknesses.
Common options include:
- 30 mm
- 40 mm
- 50 mm
- 80 mm
The appropriate thickness depends on the required thermal performance and building design.
Isoboard Ceiling Insulation
Isoboard is one of the best-known XPS thermal ceiling products in South Africa.
Unlike conventional bulk insulation that is hidden above Rhinoboard or another ceiling board, Isoboard can create a finished ceiling surface.
This makes it particularly attractive for exposed-roof structures.
It also differs substantially from glass wool and polyester insulation, which is why comparing Isoboard directly with a roll of ceiling insulation purely by thickness can be misleading.
Summit XPS Ceiling Boards
Summit XPS performs a similar broad function.
It is a rigid thermal insulation board available in multiple thicknesses and board lengths.
It can be used where a clean thermal ceiling is required and can be particularly effective in buildings where conventional ceiling insulation above plasterboard is not practical or desirable.
Among the different types of insulation, XPS should therefore be viewed as a separate insulation and ceiling system rather than simply another alternative roll.
5. Acoustic Insulation
Thermal insulation and acoustic insulation are closely related but are not identical objectives.
Thermal insulation is primarily intended to resist heat transfer.
Acoustic insulation is designed to absorb or reduce sound transmission.
Some insulation products perform both functions particularly well.
This is why glass mineral wool and other fibrous products are frequently used inside:
- Drywall partitions
- Acoustic ceilings
- Office partitions
- Studios
- Bedrooms
- Entertainment rooms
- Commercial buildings
When comparing types of insulation for acoustic purposes, density, thickness, construction and the complete wall or ceiling system all matter.
Simply placing insulation in a wall does not automatically make the wall soundproof.
Acoustic Insulation for Drywall Partitions
Drywall systems normally consist of:
- Steel or timber framing
- Insulation within the cavity
- Gypsum boards
- Appropriate fixing and finishing
Acoustic insulation placed inside the wall cavity can improve the overall sound performance of the partition.
Specialist products such as acoustic rolls or cavity batts can be selected according to the desired result.
The final acoustic performance depends on the complete wall construction rather than the insulation alone.
6. Cavity Insulation
Cavity insulation is designed for enclosed spaces within wall or building systems.
Products in this category may be supplied in batt form rather than long rolls.
The firmer format can make installation easier where the insulation needs to remain positioned vertically inside a framed cavity.
Cavity insulation can provide:
- Thermal resistance
- Acoustic absorption
- Improved performance of drywall systems
- Insulation between framed wall elements
This is one of the types of insulation where choosing the correct density and product specification is especially important.
A ceiling insulation roll should not automatically be substituted for a specialist cavity product without considering the required performance.
7. Reflective Foil Insulation
Reflective insulation works differently from conventional bulk insulation.
Products such as Sisalation, Radenshield and Alububble use reflective surfaces to reduce radiant heat transfer when installed as part of an appropriate roof or building system.
Reflective products are commonly used:
- Under roof sheeting
- Under roof tiles
- In industrial buildings
- In agricultural buildings
- As vapour or moisture-control layers where specified
- In combination with other insulation systems
Reflective foil should not automatically be treated as a direct replacement for thick bulk ceiling insulation.
These types of insulation rely on the correct installation arrangement, including appropriate air spaces where required.
Their effectiveness therefore depends strongly on how the complete roof system is designed.
Bulk Insulation vs Reflective Insulation
Bulk insulation and reflective insulation work in different ways.
Bulk insulation
Examples include:
- Aerolite
- Knauf
- Isotherm
- Mineral wool
Bulk insulation primarily resists heat conduction through the trapped air within the material.
Reflective insulation
Examples include:
- Sisalation
- Radenshield
- Alububble
Reflective insulation is primarily used to reduce radiant heat transfer as part of an appropriate building assembly.
In some roofs, both types of insulation may form part of the overall thermal strategy.
8. Industrial Insulation
Residential ceiling insulation represents only one part of the insulation industry.
Industrial buildings may require very different types of insulation depending on the roof structure, operating temperatures, fire requirements and application.
Products can include:
- Factorylite
- Energylite
- EnergyBatt
- High-density insulation
- Industrial glass wool
- Mineral wool
- Insulation used around equipment and services
These products should not automatically be grouped with residential ceiling insulation.
Factorylite Insulation
Factorylite is primarily intended for larger commercial and industrial roof applications.
Typical uses include:
- Factories
- Warehouses
- Industrial buildings
- Large-span metal roofs
- Commercial structures
It is supplied in large rolls and is generally used as part of an industrial roof-insulation system.
Factorylite therefore has a different market from the Aerolite, Knauf and Isotherm products commonly used above residential ceilings.
This distinction is important when comparing different types of insulation.
9. High-Temperature Industrial Insulation
Some industrial applications involve considerably higher temperatures than normal building insulation.
Specialist products are available in different densities and thicknesses for applications involving:
- Industrial equipment
- Ducting
- Pipework
- Process environments
- High-temperature systems
Energylite and EnergyBatt are examples of specialist industrial insulation products.
These should be selected according to the operating temperature, density, thermal performance and system requirements.
Residential ceiling insulation should never simply be substituted into a specialist industrial application.
10. Other Types of Insulation
A complete discussion of types of insulation should acknowledge other materials available in the building industry.
These may include:
Cellulose insulation
Cellulose is a loose-fill or blown insulation manufactured primarily from processed paper fibres.
Installation normally requires specialised blowing equipment.
It is available in South Africa, although Roof Insulations currently focuses on other insulation systems.
Spray foam insulation
Spray-applied foam creates an expanding insulation layer that can adhere to roof and wall surfaces.
It can be useful in specialist situations but requires careful product selection and professional application.
Fire performance, compatibility with the building and long-term accessibility should all be considered.
Expanded polystyrene
Expanded polystyrene, or EPS, is another rigid foam product used in a variety of construction applications.
It is different from XPS in its manufacturing process and physical properties.
These less frequently supplied types of insulation may suit particular building systems, but they should not automatically be assumed to outperform the more established ceiling-insulation options.
Comparing the Different Types of Insulation
The following provides a simple overview.
| Insulation Type | Typical Application | Form | Main Benefit |
|---|---|---|---|
| Glass wool | Residential ceilings | Roll | Strong thermal performance |
| Glass mineral wool | Ceilings and acoustic applications | Roll/batt | Thermal + acoustic |
| Polyester | Residential ceilings | Roll | Flexible and soft handling |
| XPS | Thermal ceilings | Rigid board | Insulation + finished ceiling |
| Acoustic insulation | Walls/ceilings | Roll/batt | Sound absorption |
| Cavity insulation | Drywall/walls | Batt | Thermal + acoustic |
| Reflective foil | Roof systems | Roll/foil | Radiant heat control |
| Industrial insulation | Factories/warehouses | Roll/batt | Large-scale thermal insulation |
| High-temperature insulation | Industrial equipment | Batt/board | Specialist thermal performance |
This table is a useful starting point, but it should not replace checking the actual product specifications.
Which Type of Insulation Has the Best R-Value?
There is no useful answer based purely on material name.
R-value depends on:
- Material
- Thickness
- Density where relevant
- Thermal conductivity
- Product construction
A 50 mm product should not automatically be compared with a 135 mm product and then used to decide which insulation material performs best.
Always compare products at appropriate thicknesses.
When evaluating different types of insulation, the declared R-value is considerably more useful than simply looking at how thick or heavy the product appears.
What Is R-Value?
R-value measures resistance to heat flow.
The higher the R-value, the greater the material’s resistance to heat transfer.
For roof and ceiling insulation, the complete roof assembly is important.
South African energy-efficiency requirements are addressed through SANS 10400-XA, which considers roof assemblies and energy zones.
The current 2021 edition should be used when regulatory compliance is being assessed.
This is important because choosing between types of insulation based solely on a commonly quoted thickness does not necessarily establish compliance for every building.
Which Types of Insulation Are Best for South African Ceilings?
For conventional residential ceilings, the three products most frequently considered are:
Aerolite
Glass wool Aerolite insulation with established residential use.
Knauf Insulation
Glass Knauf mineral wool suitable for both thermal and acoustic applications.
Isotherm
Polyester Isotherm insulation used above residential ceilings.
If the ceiling itself must provide the thermal insulation and finished surface, XPS products such as Isoboard and Summit XPS become more relevant.
There is therefore no single winner among all types of insulation.
The best choice depends on the building.
Which Insulation Is Best for an Existing House?
For an existing house with a conventional ceiling and accessible roof space, flexible bulk insulation is generally the most practical option.
Consider:
- Existing insulation
- Available roof space
- Beam spacing
- Access
- Required R-value
- Budget
- Installation difficulty
Aerolite, Knauf or polyester insulation can all be installed in retrofit applications.
Installation quality is critical.
A correctly specified product fitted neatly across the entire ceiling will generally be more useful than an expensive product installed badly.
Which Insulation Is Best for an Exposed-Beam Ceiling?
If the roof structure is exposed and there is no conventional ceiling cavity, rigid XPS thermal ceiling boards can be more suitable.
Isoboard and Summit XPS can provide:
- Thermal resistance
- A finished ceiling surface
- Clean appearance
- Multiple thickness options
This is why the best insulation cannot be selected without first understanding the roof construction.
Different types of insulation solve different building problems.
Which Insulation Is Best for Sound?
For sound control, fibrous acoustic insulation installed within an appropriate wall or ceiling system is generally the relevant category.
Products may include:
- Glass mineral wool
- Acoustic rolls
- Cavity batts
- Specialist mineral wool
Thickness and density matter, but so does the wall construction.
Sound can travel through:
- Doors
- Windows
- Ceiling voids
- Floors
- Structural connections
- Gaps around services
Acoustic insulation should therefore be designed as part of a complete system.
Which Types of Insulation Are Best for Factories?
Industrial buildings require a different approach from residential houses.
Factorylite and other industrial products may be appropriate for large-span roof structures.
High-temperature industrial systems may require Energylite, EnergyBatt or other specialist materials.
Consider:
- Operating temperature
- Roof construction
- Fire performance
- Condensation
- Required R-value
- Building use
- Product density
- Installation system
Using a residential product simply because it is cheaper is not necessarily appropriate.
How to Choose Between Different Types of Insulation
Before purchasing insulation, answer these questions.
1. What are you insulating?
Is it:
- A residential ceiling?
- Exposed beams?
- A drywall partition?
- A factory roof?
- An acoustic room?
- Industrial equipment?
This immediately eliminates many unsuitable products.
2. What thermal performance do you require?
Check the R-value rather than comparing thickness alone.
3. Is acoustic performance important?
If yes, consider products specifically suited to combined thermal and acoustic applications.
4. How will the insulation be installed?
Some products can be laid above ceilings.
Others become part of the ceiling itself.
Others are installed inside walls, below metal roof sheeting or around industrial equipment.
5. What is the cost per square metre?
Do not compare roll prices without checking roll coverage.
6. Is the product suitable for the building?
Check:
- Fire performance
- Thermal performance
- Moisture requirements
- Installation instructions
- Product certification
- Intended application
This approach makes comparing types of insulation far more meaningful than simply asking which product is cheapest.
Bulk Insulation or Thermal Ceiling Boards?
This is another important distinction.
Choose bulk insulation where:
- A conventional ceiling already exists
- Roof access is available
- The insulation will be hidden above the ceiling
- A retrofit solution is required
Consider XPS thermal ceiling boards where:
- There is no conventional ceiling
- Beams are exposed
- A finished thermal ceiling is required
- The ceiling surface and insulation need to form one system
Neither approach is automatically better.
They serve different building designs.
Insulation Installation Matters
The performance of all types of insulation depends partly on correct installation.
Common problems include:
- Gaps
- Poor cutting
- Uninsulated sections
- Excessive compression
- Incorrect fitting around roof members
- Displaced insulation
- Improper treatment around electrical equipment
The roof should be measured properly and the insulation fitted as consistently as possible.
High-quality insulation cannot compensate completely for a badly installed ceiling.
Frequently Asked Questions About Types of Insulation
What are the main types of insulation in South Africa?
The main types of insulation include glass wool, glass mineral wool, polyester, XPS rigid boards, acoustic insulation, cavity insulation, reflective foil and specialist industrial insulation.
What are the most common types of roof insulation?
For residential roofs, Aerolite, Knauf and polyester insulation are commonly considered. XPS boards are used for thermal ceilings, while reflective foil and industrial products serve different roof systems.
What types of ceiling insulation are available?
Common types of ceiling insulation include glass wool, glass mineral wool, polyester and rigid XPS thermal ceiling boards.
What is the best type of insulation?
There is no universal best product. The correct insulation depends on the building, required R-value, roof design, application, budget and installation method.
Is glass wool good insulation?
Yes. Properly specified glass wool provides strong thermal performance and has been widely used for residential and commercial insulation.
Is Knauf the same as Aerolite?
No. Both fall into the broad mineral-fibre insulation category, but they are different products from different manufacturers and should be compared using their individual specifications.
Is polyester better than glass wool?
Not automatically. Compare R-value, thickness, fire performance, cost, coverage and installation requirements rather than choosing according to material alone.
Is XPS better than ceiling insulation rolls?
They perform different roles. XPS is particularly useful when a rigid thermal ceiling is required. Flexible rolls are generally more appropriate above existing conventional ceilings.
Does thicker insulation always perform better?
Within the same product family, increasing thickness will normally increase thermal resistance. However, different insulation products should be compared using their declared R-values rather than thickness alone.
Is acoustic insulation also thermal insulation?
Many fibrous acoustic insulation products also provide thermal resistance, but acoustic and thermal performance are measured differently.
What insulation is best for drywall?
Acoustic or cavity insulation installed between the framing can improve both thermal and sound performance. The complete drywall system determines the final result.
What insulation is used in factories?
Factorylite and other industrial insulation systems are designed for large commercial and industrial buildings. Specialist high-temperature products are used where operating conditions require them.
Is reflective foil the same as bulk insulation?
No. Reflective foil and bulk insulation work differently. Reflective products primarily address radiant heat transfer, while bulk insulation resists heat transfer through its material structure.
Can different types of insulation be combined?
Yes, some building systems use more than one insulation type. However, each layer should have a specific purpose, and the complete assembly should be correctly designed.
Which insulation should I use in Cape Town?
The product should be selected according to the building construction, required thermal performance, applicable energy requirements and budget rather than choosing purely according to location.
Choosing the Right Insulation for Your Property
Understanding the different types of insulation makes it much easier to select the correct product.
For most South African homeowners, the decision can be simplified into several broad categories:
Existing conventional ceiling:
Consider Aerolite, Knauf or polyester ceiling insulation.
Exposed-beam or thermal ceiling:
Consider Isoboard or Summit XPS.
Drywall or acoustic application:
Consider acoustic rolls, cavity insulation or appropriate mineral wool.
Industrial roof:
Consider Factorylite or another correctly specified industrial insulation system.
High-temperature industrial application:
Use a specialist industrial insulation designed for the operating conditions.
Reflective roof application:
Consider the appropriate Sisalation or reflective foil system.
There is no reason to make insulation more complicated than it needs to be.
Start with the application, determine the required performance and then compare only the types of insulation suitable for that job.
Need Help Choosing Between Different Types of Insulation?
Roof Insulations supplies thermal, acoustic and industrial insulation products for residential, commercial and industrial applications.
Our range includes products such as:
- Aerolite Insulation
- Knauf Insulation
- Isotherm Insulation
- Isoboard
- Summit XPS
- Factorylite
- Acoustic insulation
- Cavity insulation
- Energylite and EnergyBatt
- Sisalation and reflective foils
If you are unsure which of the different types of insulation is suitable for your building, compare the application, thickness, R-value and product specifications before buying.
Choosing the correct insulation from the start can prevent unnecessary expense and ensure that the product is suited to the job for which it was designed.
