Types of Insulation
Finding the right type of insulation is important for you and your home. You need to take into consideration where you plan for the insulation to go, what space or area the insulation is to go into in your home, and the insulation materials that work best for your home. There is a broad variety of insulation for you to choose from. At a high level your choices of insulation include insulation batts and blankets, reflective insulation and insulation boards. Each of these types of insulation then has a variety of different materials and forms.
Bulk insulation
Bulk insulation such as insulation batts, insulation blankets, and loose-fill insulation contains millions of tiny pockets of still air trapped within the insulation material. This still air provides the bulk-insulation material's insulating effect so it is important that you do not compress bulk insulation.
Insulation Batts and Insulation Blankets
Glasswool Insulation (fibreglass)
Glasswool insulation is fabricated from melted glass spun into a flexible mat of fine fibres.
The benefits of glasswool insulation are:
- Available in a choice of insulation batts or insulation blankets
- Cutting and installing is easy
- They can be easily found in hardware stores in DIY packs with R values clearly labeled
When handling glasswool insulation remember that:
- It should not be compressed or moistened
- All ends and edges should be butted together firmly when installing the insulation
- Insulation blankets are thinner and denser than batts. They are also available with reflective foil attached to one side
Rockwool Insulation
Rockwool insulation is made from volcanic rock melted at very high temperatures and spun into a mat of fine fibres.
The benefits of rockwool insulation are:
- You have a choice of insulation batts or insulation blankets
- Rockwool is denser than glasswool. Therefore you have a higher R value per unit thickness.
- Rockwool has better sound absorption than glasswool insulation.
However, generally rockwool insulation is more expensive than glasswool insulation.
Natural wool Insulation
Natural wool insulation is made from sheep's wool that is formed into insulation batts or insulation blankets.
The benefits of natural wool insulation are:
- A natural fibre insulation used in your home.
- Natural wool insulation is naturally flame-resistant. However, the addition of synthetic fibres increases flammability.
When purchasing natural wool insulation, consider:
- Natural wool insulation should only be manufactured from new wool, that has been treated with a vermin and rotproofing agent.
- Moth-proofing of natural wool insulation is vital. Check with the manufacturer for test results.
- Most natural wool insulation batts and insulation blankets are made of a woolpolyester blend to reduce settling and compression
- Different types of natural wool insulation can result in different R values for the same thickness.
Polyester Insulation
Polyester insulation is made from polyester fibres, such as recycled PET bottles, that have been spun into a flexible mat.
The benefits of polyester insulation are:
- Its available as insulation batts or insulation blankets
- It has similar properties to mineral wool, but is non-irritable.
- It does not burn. However, it will melt if exposed to a flame at high temperatures.
Loose-fill insulation
Loose fill insulation consists of shredded or granulated material supplied in a loose form. It is normally installed by the supplier or manufacturer. It is important that loose fill insulation is installed correctly, and at the correct depth to provide the right insulation cover. Also, barriers need to be installed to prevent loose fill insulation falling through light fittings, exhaust fans, wall cavities, and ceiling vents.
Loose-fill insulation material may settle over time. This may reduce its effectiveness. Therefore, when purchasing loose fill insulation you should ask for a "settled R Value" rating from your installer.
Loose fill insulation is best suited to flat ceilings with less than a 25 degree pitch. Also, loose-fill insulation is only suitable for insulating ceilings.
Cellulose Fibre Insulation
Cellulose fibre insulation is made from waste paper pulverised into a fine fluff.
The benefit of cellulose fibre insulation is that it can be cheaper to purchase and install than other types of bulk insulation. However, the quality and installation can vary greatly. It must also be treated with fire retardant chemicals to reduce flammability.
Natural Wool Insulation
Loose fill natural wool insulation is made from sheep's wool off-cuts.
When purchasing loose fill natural wool insulation, you should consider:
- It should consist of pure, new wool only. It should not contain any synthetic fibres or recycled materials.
- Cheaper grades of wool are commonly used. Therefore, you may find small leather fragments, however this should not affect its performance.
- You should be treat the natural wool insulation with a vermin and rotproofing agent.
Granulated rockwool
There is also a loose-fill form of rockwool insulation.
One use of loose-fill rockwool insulation is to treat it with a water repellant and fill cabity brick and brick veneer walls. I
Reflective Insulation
Reflective insulation is fabricated from thin sheets of highly reflective aluminium foil laminate. This material reflects heat from its polished surfaces while absorbing and emitting only a minimal amount. For maximum effectiveness, reflective insulation should work in conjunction with a still air layer.
When using reflective insulation any gaps or tears will significantly reduce performance. Similarly, dust buildup on surfaces can reduce the effectiveness of reflective insulation.
There are currently four types of reflective insulation products available. They are reflective foil laminate, multi-cell refelctive foil products, expandable concertina-style foil, and foil bonded to bulk insulation.
Reflective foil laminate insulation
Reflective foil laminate insulation is foil laminated to paper with glass fibre reinforcement.
Some factors to consider in purchasing reflective foil laminate insulation are:
- It is supplied in rolls.
- It is normally used for roof sarking and wall insulation.
- Double-sided reflective foil is more effective than singlesided.
- Double-sided reflective foil is more water resistant.
- Double-sided foil is commonly made with an anti-glare coating. This can reduce the insulation's effectiveness by around 10 per cent.
Multi-cell reflective foil insulation products
Multi-cell reflective foil insulation products are 2, 3 or 4 layers of laminated foil separated by partitioning to provide a multi-layered cell structure.
Multi-cell reflective foil insulation products:
- Can be installed over ceiling joists and between or across wall studs.
- Need to be butted firmly together. This prevents air movement through gaps.
- R value depends on the number of cells and the number of layers.
Expandable concertina-style foil insulation
Expandable concertina-style foil insulation is double-sided reflective foil formed into an expandable concertina.
This type of insulation is:
- Used predominantly underneath timber floors and between wall studs.
- Adjustable in width to suit different sized gaps.
Expandable concertina-style insulation should be installed with an adjacent sealed air space. It should also be well sealed against the building frame
Foil bonded to bulk insulation
Foil bonded to bulk insulation is reflective foil bonded to insulation batts, insulation blankets or polystyrene boards.
Using foil bonded to bulk insulation increases insulation benefits when installed with the foil facing still air space.
The most common method of insulating cathedral ceilings and under flat roofs is foil bonded to blanket insulation.
Insulation Boards
Insulation boards are used predominantly in walls and cathedral ceilings.
Extruded polystyrene insulation
Extruded polystyrene insulation is rigid, waterproof boards of closed cell polystyrene.
This type of insulation:
- Has high compressive strength.
- Contains flame-retardants. However, installation is only recommended between non-combustible materials.
- Has very high R value per unit thickness.
- Has some products available with reflective foil backing.
However, generally extruded polystyrene insulation is more expensive than other types of bulk insulation.
Foil-faced expanded polystyrene insulation
Foil-faced expanded polystyrene insulation is rigid boards of polystyrene beads with reflective foil attached to both sides.
This type of insulation:
- Should be installed with the foil facing still air spaces of at least 2.5 cm width to ensure the best R value.
- Has a lower R value per unit thickness than extruded polystyrene.
- Is also available as boards without foil facing. These have very similar properties to extruded polystyrene, however have lower compressive strength and are not water resistant.