Frequently Asked Questions

Which way do I face the foil side of Permastop Building Blanket?

Which way the foil faces relates to which direction radiant heat needs to be reflected back, and, for specific projects and locations, the condensation risk.

Typically, in warm to cold climates (Climate zones 2-8) the foil should face inwards – towards the building interior. Installing the glasswool blanket in continuous contact on the underside of the metal roof maintains the internal temperature, reducing the risk of reaching dew point and condensation. The foil layer on the underside of the glasswool blanket reflects radiant heat and when taped and completely sealed is a vapour barrier.

In hot and humid climates (Zone 1) the foil should face outwards – towards the metal roof sheet or wall cladding, and be completely taped and sealed, to keep moist air out (water vapour) so it doesn’t migrate into the internal conditioned space. An additional foil membrane on the internal side of Permastop Building Blanket is recommended in tropical climates with air conditioned spaces. Fletcher Insulation offers Permastop Tropic specially designed for these higher humidity climate zones, which has foil on both sides of the building blanket.

For more detailed information on installing Permastop Building Blanket, please refer to the Installation Guide for Permastop in the Resources section. Or contact our Technical team for project specific commendations.

Do I need to tape the foil overlap on Permastop?

If a vapour barrier is required, the answer is YES.

A vapour barrier needs to form a continuous and airtight barrier to prevent the movement of moisture laden air (significant amounts of water vapour). If there are gaps, seams, or openings in the foil membrane, water vapour can penetrate through these areas, compromising the effectiveness of the vapour barrier. Taping helps create a seamless and continuous barrier. It’s important to use appropriate tapes that are designed for this purpose and are compatible with the specific membrane material.

Refer to the Installation Guide for Permastop in the Resources section for more information.

Does glasswool insulation installed in timber stud frames keep noise out?

Yes, glasswool insulation installed in timber stud frames can help reduce the transmission of sound, providing a level of acoustic insulation. Glasswool insulation is known for its ability to absorb and dampen sound waves, making it an effective material for soundproofing applications.

Here are the ways in which glasswool insulation can contribute to sound reduction in buildings:

Sound absorption: glasswool has a fibrous structure that helps absorb sound waves. When sound waves pass through the insulation material, they encounter the fibres, which convert the sound energy into heat energy through friction. This process reduces the amplitude of the sound waves and contributes to a quieter indoor environment.

Damping impact noise: glasswool insulation can also help dampen impact noise, such as footsteps or the impact of objects against surfaces. The fibrous nature of the material absorbs and disperses the energy generated by impact, reducing the transmission of sound through the structure.

Improving sound quality: In addition to reducing the transmission of unwanted external noise, glasswool insulation can improve the internal sound quality by reducing echoes and reverberation within a space. This is beneficial in areas where clear communication or a comfortable acoustic environment is desired.

While glasswool insulation can contribute to noise reduction, it’s important to note that achieving optimal acoustic performance involves considering the overall design of the building, including factors like wall construction, floor / ceiling assemblies, and the use of special soundproofing materials such as acoustic plasterboard. Additionally, proper installation practices, including sealing gaps and ensuring a tight fit, are important to maximise the insulation’s effectiveness in reducing both airborne and impact noise.

As a general rule the greater the density of glasswool, the greater the improvement in sound quality. Our Pink Soundbreak range is designed to improve noise reduction in residential buildings. You’ll find more details in the Products section or contact us for advice.

Do reflective roof sarkings and wall wraps have an R-value?

While the material itself lacks an R-value, a reflective surface facing an air cavity can contribute to an effective Total R-value of the roof or wall system by blocking radiant heat. The specific R-value depends on the system used and the direction of heat transfer. For instance, roof sarking in a pitched metal roof with a flat ceiling may add approximately R1.36 in summer, and reflective wall wraps can contribute around R1.1 in summer when combined with a non-ventilated air space in the stud frame.

Contact us for information on system R-values delivered from specific roof sarkings. We have modelling software that can show the difference in performance for the various roof sarking materials.

How do reflective foil sarkings and wall wraps block radiant heat?

All objects emit infrared radiation or radiant heat from their surface in all directions, travelling in a straight path until the heat energy encounters another object which itself reflects or absorbs radiant heat. Fortunately, aluminium foil has properties that mean it is highly reflective, and the reason why it is used in roof sarkings and wall wraps. The combination of the foil’s metallic nature, smooth surface, thinness, and thin oxide layer on the surface all contribute to its excellent reflectivity.

Reflection of radiant heat can only occur in an adjacent air space. It’s essential to have an air gap adjacent to the reflective layer if radiant heat needs to be reflected outwards. In that case, the foil side faces outwards. When radiant heat needs to be reflected back inside a building to help keep warmth in, the foil side will face inwards.

Choosing the right type of roof sarking or wall wrap depends on factors such as climate zone, building type and application and specific use of the building. Our Technical team can assist you with recommendations.

Which insulation batt is recommended for optimal acoustic and thermal performance in homes?

Fletcher Insulation’s Pink® Soundbreak® batts are the perfect solution for both great acoustic and thermal performance in homes.

Pink Soundbreak batts are the trusted acoustic batt solution – reducing noise transferring from the outside in, and between different areas and spaces within the home such as upper floors, media rooms and bathrooms. The density of a glasswool batt is particularly important when it comes to acoustics. A range of Pink Soundbreak densities has been tested – with a Noise Reduction Coefficient (NRC)* rating for each one. That means you can choose the type of Soundbreak batt that meets your specific needs, room by room if you so desire. The range is comprehensive with densities starting at an impressive 24kg/m3, going up to 32kg/m3.

Then there is the other big advantage of choosing Soundbreak batts – and that’s their thermal performance. They play a significant role in keeping your home more comfortable through the seasons with better control over energy costs. Again the range is impressive going up to a 2.7 R-value in the 90mm batt.

And they’re made in Australia by Fletcher Insulation to the same high quality standards you expect.

For more information on the thermal and acoustic properties of Pink Soundbreak, refer to the Technical Data Sheet in the Resources section or reach out to our Technical team.

* Noise Reduction Coefficient (NRC) is a measure of a material’s effectiveness in absorbing sound across a range of frequencies. It is commonly used in acoustics to quantify the sound absorption characteristics of various surfaces and materials. The NRC is expressed as a decimal between 0 and 1, where a higher NRC indicates better sound absorption.

What is the best insulation product to use in my shed?

Sisalation® Foam Cell Shed Liner is specially designed for wall and roof applications in sheds and garages that aren’t habitable. It can reduce up to 95% of the sun’s radiant heat, minimises the risk of condensation and acts as an effective water and vapour barrier when installed according to AS/NZS 4200.2. We suggest discussing your requirements with your shed builder to ensure compatibility with the overall system. We can also assist with options.

Can I use a 70mm insulation batt in a 90mm frame?

Yes you can, but ideally select a batt that will snugly fit both the width and thickness of the frame for optimal thermal performance. For full details on how to install batts correctly, read our Installation Guides which can be found in the Resources section.

Can insulation be compressed to fit into a smaller frame?

We do not recommend compressing insulation. The designed thickness delivers the stated R-value and any compression will result in a reduction in performance. Fletcher Insulation offers a range of products designed for the various frame thicknesses. For more information refer to the Products section or contact us for advice.

Are your glasswool products non-combustible?

Yes, all our unfaced FBS-1 Glasswool materials up to 48kg/m3 are non-combustible. They have been tested and assessed by the CSIRO to Australian Standard AS 1530.1-1994. This is a considerable benefit compared with polyester batts, as glasswool batts don’t burn when exposed to fire and don’t contribute to the fire load. Refer to the relevant Technical Datasheet (TDS) and Safety User Information Sheet (SUIS) in the Resources section for further details.

What is the difference between ‘breather ‘and ‘vapour permeable’ wall wraps and roof sarkings?

Traditional breather products, like pin-perforated aluminium foil laminates, allow some vapour transfer but aren’t air or water barriers. We recommend their use in suitable brick veneer applications in Climate Zones 2-5*. Vapour Permeable products, such as Vapawrap, allow water vapour transfer, prevent liquid water entry, provide an air barrier when taped, and have higher drying potential. They are suitable for lightweight cladding and brick/masonry applications in Climate Zone 2-8**.

*Sisalation Tuff Wrap Breather is not suitable for a light wall system in Climate Zones 2-8 where a water barrier is required.

**Sisalation Vapawrap Residential Wall Wrap is vapour permeable Class 4 and is suitable for use behind fibre cement lightweight cladded walls in Climate Zones 2-8. Please refer to the facade system manufacturer for details.

How do I calculate the number of Sisalation Foam Cell rolls I need with the 150mm overlap on the product?

All our Sisalation Foam Cell products come with a 150mm overlap (except Bubble Cell) and include the overlap area in the ‘Area per roll m2’ figure.

Simply take the square metres required for your project and divide by our ‘Area per roll m2’ figure to determine the number of rolls you’ll need.