Which type of roof insulation is best?

Tips for installing roof insulation

There are two main categories of roof insulation; bulk and reflective insulation. Bulk insulation has millions of tiny air pockets and works by trapping air within its structure. Bulk insulation cannot be compressed as this will reduce its air pockets and compromise its insulating ability. This insulation works by reducing the conduction of heat flow between objects that are adjacent to each other. On the other hand, reflective insulation primarily affects radiation heat flow. It usually consists of a foil layer backed by a paper or plastic layer. Reflective foil needs to be kept clean for it to work properly, and the reflective side must be faced downwards. More recently, roof insulation has been designed to incorporate both bulk and reflective insulation for highest performance and insulating capabilities.  

What is roof insulation made of?

Roof insulation is made from a number of different materials, depending on whether it is bulk and/or reflective insulation. The most common bulk insulation materials used are; glasswool, and polyester. At Pricewise Insulation we have a variety of glasswool and polyester roof insulation products to suite your homes, and desired thermal performance.

Glasswool insulation is the most common insulation material used in both residential and commercial building. Although glasswool has a stigma of being itchy and uncomfortable to install, recent technological advances have improved this and today many glasswool insulation products claim to be low-itch or itch free.

Glasswool roof insulation products include;

  • Knauf Earthwool Ceiling Batts
  • Pink Batts Glasswool Ceiling Insulation
  • Bradford Hi-Performance Gold Ceiling Batts
  • Bradford Black Hypoallergenic Ceiling

Polyester insulation is manufactured from recycled PET plastics such as drink bottles. Polyester insulation is bonded together by heat and no binder chemicals are added. This gives polyester its rigid, flexible and hypoallergenic structure.

Polyester roof insulation products include;

  • Greenstuf Polyester Ceiling Insulation
  • Bradford Polymax Thermal Ceiling Insulation Batts

Foil insulation has a reflective surface which creates a radiant barrier against heat transfer from the sun. It is important that foil insulation is installed correctly to ensure its full insulating capabilities are reached. The R-value of reflective foil insulation will depend on how it is installed and what climate you are living in. Roof foil insulation products available at Pricewise insulation include;

  • Kingspan Air-Cell Insulbreak 70
  • Sisalation Metal Roof Sarking

The following products combine both bulk and reflective insulation:

  • Knauf Earthwool Roofing Blanket Roll with Foil Facing
  • Fletcher Permastop Building Blanket Insulation

Should I install roof insulation batts or rolls?

Insulation batts vs rolls

This depends entirely on your own personal preference as functionally; both these forms are equally effective at insulating. The main difference is the way in which they are installed. Roll insulation, can be ‘rolled’ out between the ceiling joists without needing to be cut into segments. This is especially useful for ceiling spaces that have few obstacles and a large space to work in. However, if you have many obstacles and a small ceiling space area, insulation batt may be a more appropriate option. As batts are pre-cut, they are easy to install and cut to fit any space.

7 thoughts on “Which type of roof insulation is best?

  1. Richard lickfold says:

    Hi
    I have a 30 x12 metre colour bond shed with no insulation roof or walls
    Can you advise what product you suggest to install, what difference in heat can I expect and a cost
    Regards

    • Pricewise Insulation says:

      Hi Richard,

      There are several options that we have for sheds. We generally recommend Kingspan Insulshed Insulation, but it really depends what the shed is going to be used for. Some people install battens and insulation batts and sometimes rigid board insulation is also an option. The cost and thermal effectiveness will differ according to which product you choose. Feel free to give us our technical specialists a call on 1300 729 639 to discuss your project.

      Cheers!

  2. Geoff says:

    What type of insulation do you recommend for a tin skillion roof in Perth. I therefore have no crawl space so I have to lift the tin and install. I was thinking just rolling out sisalation sarking but I’m just really wanting an idea of what is best, as the sun is really strong here. It’s a 1960’s house so not great in summer or winter.
    I will be adding solar panels if that makes a difference.
    Thanks for your help.

      • Tony says:

        Hi
        I am replacing the truss roof on a single brick walled garage of 9.5m x 3.5m and 2.4m ceiling height to renovate into a granny. Given the small space, I want to put in redundant sound and heat insulation.
        As advised above I will lay “R7.0 Bradford Gold™ Hi-Performance Acoustic Ceiling Insulation” over the ceiling from the top.
        For the reflective sarking, do you recommend “Kingspan Air-Cell Insulbreak 80 Insulation” or “Kingspan Air-Cell Insuliner® Insulation” ? Is there any video or instruction on how to lay this to preserve the air gap to reduce conduction heat transmission. The roof is an A frame with a single middle joist underneath and a single middle batten on top of the truss/rafter. I can send the photo if required.

        Also the garage rolling shutter will be replaced with a stud wall and a door. It has the option of both inside thermal and outside sound insulation. The street has heavy traffic so can you please suggest the best sound insulation for the door ?
        Thanks
        Tony

    • Pricewise Insulation says:

      Hi Devan,

      Thanks for your question. Good insulators are products which are effective at stopping the flow of heat energy. Glasswool and polyester insulation batts work by trapping air in layers, which is a very effective way to keep the heat out in summer and the cold out in winter. In Australia you can determine the effectiveness of an insulation product by checking its R-value. The higher the R-value, the greater the thermal performance of the insulation. We would also recommend only purchasing reputable brands such as Earthwool, Bradford, Autex GreenStuf and Pink Batts. Please feel free to give our team a call on 1300 729 639 if you have any further questions.

      Cheers!

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