polyester vs glasswool
polyester vs glass wool


When you spend money on insulation for your home, you create future assurance in energy efficiency and comfort. There are some vital questions that need to be answered when thinking about the type of insulation to use. Let us take a look at polyester vs glasswool.

Fibreglass / glasswool is the primary component in the manufacture of the most popular ceiling insulation products sold in South Africa. There are many benefits of using glasswool insulation material.

It has a very high fire rating. The highest in its class. It is made from recycled glass and sand. Additionally, it does not absorb moisture, attract vermin or rot. The material is also easy to cut during installation. The product is made with millions of tiny air pockets that trap heat. This is how glasswool reduces heat penetration.

We will compare glasswool to polyester. In addition to having most of the above benefits, polyester has a few added advantages. It is easy to handle and has no breathable, itchy fibres. On the other hand, polyester has a slightly lower fire rating than glass wool.


  • Non-Allergic and non-Itch
  • Safe and user-friendly
  • No dust or loose fibres
  • Handles moisture well
  • Widely available
  • Full range of R-value products
  • Slightly lower R-values than fibreglass for the same thickness
  • High recycled content
  • Suitable for residential and commercial properties


  • Widely available. Most common materials
  • Full range of R-values for walls, ceilings and underfloor insulation
  • High recycled content – sand and glass
  • Suitable for residential and commercial properties
  • Itchy to work with (fibreglass)
  • Protective gear needed
  • Higher fire ratings than polyester products
  • Doesn’t handle water damage well
  • Up to 50-year lifespan


Polyester insulation is ideal for use by people who are asthmatic. It does not contain chemicals, fibreglass or dust. No protective gear is needed to install this product.

However, old ceilings are bound to have accumulated a lot of dust regardless of whether the roof space has been insulated and the type of insulation used. All factors held constant; polyester remains the least dusty insulation material especially for a new building.


You should also consider the cost of having the insulation products delivered to the site. Polyester is bulkier than glasswool. If you are near South Africa’s cities such as Johannesburg and Pretoria, transportation costs cease to be a major concern.

For example, insulating a 130-meter square ceiling using earthwool insulation will require only one pallet. Four pallets would be required when trasporting isotherm insulation. The variance will translate to an increase of about 20-30 per cent in freight costs if you live far away from the cities.