Home Insulation - Consideration and Types
Insulating your home ensures that the temperature inside your home is not affected by the outside weather conditions, making it pleasant inside for you and your family. Insulation is usually installed in the roof when a home is built, however if you are doing it yourself, or you are installing extra insulation, or replacing old insulation, then you need to know some more about it.
If you are going to DIY, then you need to choose the material you want to use, and find out what level of insulation needed. It is important to get material which is the right thickness to insulate the required area. Batts can be bought from hardware stores or from insulation retailers.
If you need an expert to install the product for you, and to give you advice for your particular project, then make sure you get several quotes, and check building licenses for all workers on site.
There are several considerations when thinking about installing insulation. Insulation is one aspect of the building envelope which seals the house from the changes in outside temperature. Other aspects include window shading on the interior and exterior of the house, as well as cracks in windows and doors. Ensuring other aspects of your home are protected will make sure insulation is as effective as it can be.
Existing homes are usually already insulated in the ceiling, but you can also insulated under floors or in wall cavities. Although some experts recommend wall insulation for existing homes, it’s difficult and relatively expensive and usually only occurs during construction or a major renovation.
If you’re thinking of building, check your state’s mandatory energy rating regulations for the energy efficiency of new buildings. Check what R-value is recommended for the area you live in, and that the insulation will satisfy the rating requirements. Ask about the price per square metre of the insulation you’ve chosen. Price can vary, so ensure you find the best value. More about R-Values and how much insulation you need is below.
There are various materials insulation is made from, including mineral fibres, cellulose, polyester, sheep's wool and various other products.
Mineral fibres include glass wool, otherwise known as fibre glass, as well as rock wool. Glass wool comes in batts and blankets and is used to insulate ceilings and walls. Rock Wool is made mainly from spun fibres of molten volcanic rock. It’s available in batts and blankets, as well as in loose-fill form. It’s usually denser than glass wool, so when installed to the same thickness, it offers better insulation.
While mineral fibre insulation is easy to install yourself, and resistant to fire and insect attack, they can also cause short-term irritation to the skin, eyes and respiratory tract. Therefore if you handle these products yourself, wear protective clothing.
Cellulose is made from shredded waste paper, and sold as a loose-fill product that’s blown into your ceiling space by the supplier (you can’t do it yourself).
A mixture of borax and boric acid is added to make the material fire-retardant. These chemicals also deter cockroaches and silverfish.
Cellulose is particularly good for homes where access to roof space is difficult, although there can be a big variation in price between suppliers. While there are not the same health concerns as mineral fibre insulation, cellulose insulation can produce a lot of dust.
Polyester insulation comes in batts and blankets. Polyester products don’t burn, but in a fire they melt and give off dense smoke. There are no known health issues, but they’re generally more expensive than similar glass wool products.
Sheep’s Wool insulation is made from new and waste wool. It’s sold in batts and blankets (often in combination with polyester) and as loose-fill ceiling insulation. Prices can vary between suppliers so do your research. Experts say the quality and fire resistance of pure wool products can vary considerably.
Other materials include polyurethane and polystyrene foam boards, mineral loose-fill granulates (Perlite, Vermiculite), reflective foils, multi-cell, multi-layer laminated foil batts ('concertina batts' or 'air-cell insulation') and combinations of different materials, such as glass wool batts with reflective foil on one side.
How much insulation you need depends on the R -value of the material. According to density and depth of the insulation, the R-value is simply a measure of how good a product is at reducing the flow of heat. The higher the R-value, the more effective the insulation material is at this. Ask your local council or state energy department what ‘R-value’ for ceiling insulation is recommended for your area. It varies according to climate.
There's a standard for all insulation materials (AS/NZS 4859, parts 1 and 2). Ask the supplier for proof that the product meets the requirements of both parts of that standard. It'll guarantee the product meets its performance claims, as well as fire retardation and material-specific requirements. This will also ensure the material is at the right thickness and density.
Ask a supplier for proof that the insulation you purchased is manufactured to the Australian Standard requirements. If they can't provide one, ask for a written guarantee (or at least a recent test certificate) that the product meets the R-value you want at the quoted thickness. Make sure the installed product is the same as the one on the test certificate.
If you're buying loose-fill, ask the supplier about the fact that it may settle over time, and what maintenance services they offer. Ask for a guarantee that the material will be installed according to the requirements of AS 3999 (the Australian Standard for the installation of thermal materials).