What Type of Insulation is Right For My Home?
With energy costs on the rise it makes sense to do whatever you can to cut how much you use. Insulation is a great way of cutting your heating and cooling costs- by as much as half- and even though it may seem an expensive project initially, over time it will save you a lot. The right insulation keeps hot air outdoors in summer and warm air inside in winter. Well insulated homes can be as much as 7C cooler in summer and 10C warmer in winter, which translates into considerably less heating/cooling time to keep a comfortable temperature.
Insulation comes with its specific R-value, which informs you of its heat transfer resistance. A high insulation R-value indicates high resistance, while a low R-value means it is less resistant. R-values can either be listed as Material R-values or System R-values. Material R-values relate to the insulating material on its own, while System-R values apply to the finished system, material plus how and where it is installed. Make sure you know which R-vale you are looking at when comparing products.
Note: Check with your local building standards authority regarding any mandates covering the R-values and requirements of insulation in renovations, extensions and new buildings, before purchasing, as you may need to comply with these. Failing to check first could end up an expensive mistake!
Below, we take a look at the various insulation material options for your home, and where each type is commonly used, so that you can have a clearer idea what might best suit your particular application.
How to Choose and Use Insulation
Reflective insulation products are DIY install, if desired.
These are best used in hot climates, because, as the name implies, there 'claim to fame' is in reflecting heat away from wherever they are installed. They can deflect up to 95% of radiant heat! Dust build-up can significantly decrease their effectiveness. They are not very competent at stopping the loss of heat which flows through from inside to outside, and therefore not a great cold weather insulator. They can, however, be used in conjunction with batts which can help overcome this problem.
Reflective insulation includes:
Reflective Foil Laminates
Reflective foils are composed of aluminium foil laminated with glass fibre reinforcement. Reflective foil insulation does not have a significant R-value itself- a sealed air space of 25 mm between the foil and a solid surface is necessary to achieve full insulation. Reflective foil insulation is usually used in framed walls, above non-trussed flat and cathedral ceilings and Under timber floorboards.
Multi-cell Foil Batts
Formed by layers of laminated foil with air pockets between them, these are used commonly under timber floors, in framed walls and above cathedral ceilings.
Concertina Foil Batts
Foil and paper laminate manufactured with a concertina formation, suitable for between wall studs in framed walls and under timber flooring.
The video below talks more about reflective insulation.
Loose Fill Insulation
These products require specialist installation and are not DIY.
Loose fill insulation works on the insulating principles of the pockets of air formed, which limit the transfer of heat in both directions. It is quite a useful product for using in hard to access areas.
Varieties of loose fill insulation include:
Natural Wool Insulation
Usually treated to resist vermin and rot, this loose fill is made from off-cuts of sheep's wool. It is naturally flame resistant, but quality can vary which affects its effectiveness. Try to obtain several quotes before signing the contract, as prices can vary enormously. Keep in mind, however, that higher prices could mean a higher actual wool content, which makes for better insulation, so ask what percentage of the product is wool to make a more informed comparison. It is usually used above flat ceilings, or those with less than a 25 degree pitch.
Granulated Rock Wool Insulation
Made from molten volcanic rock, granulated rock wool is good for hard to access areas and has the added bonus of being a good sound insulator as well. It is susceptible to moisture, so is usually treated with a water repellent. It is used in wall cavities and above flat or slightly sloped ceilings.
Cellulose Fibre Insulation
As the name suggests, this is made from cellulose fibre in the form of shredded recycled paper, so is not only doing its bit as an insulator, but recycling waste products too. It is good for use in hard to access areas. As it is a flammable material, it must be treated with fire retardants. Commonly used in wall cavities and above flat or slightly sloped ceilings.
This video shows the installation of cellulose fibre insulation.
Insulation Batts and Blankets
These products are DIY install, if desired.
These products include:
Glass Wool/Fibreglass Insulation
This is made from molten glass (often a high percentage of recycled glass), spun into a mat of fine fibres, creating a product which is easy to cut and install. These fibres can cause irritation, so protective gear should be worn when installing. Used above flat or cathedral ceilings, in framed walls and under timber floors.
This video covers a chemical free, environmentally friendly type of glass wool, called Earth Wool, which uses a sugar based binder instead of chemicals such as formaldehyde, in the manufacturing process.
Rock Wool Insulation
Rock wall is made from molten volcanic rock which is spun into a mat of fine fibres. It is a dense product so less can be used to obtain the same result of another insulator, such as fibreglass. It is also a good insulator for sound. Protective gear needs to be worn when installing this material, as fibres can cause irritation, to both skin and lungs. Used above flat or cathedral ceilings, in framed walls and under timber floors.
Natural Wool Insulation
Made from sheep's wool, spun into a mat, this product is naturally flame retardant and also treated against vermin and rot. As with wool loose fill, prices can vary dramatically, so get several quotes first, including actual wool content percentage. Used above flat or cathedral ceilings, in framed walls and under timber floors.
This video discusses wool insulation.
Made from polyester threads (often with a high recycled percentage including PET bottles) spun into a mat, this product can be more expensive than similar products, however it is a non-toxic material which is not hazardous to health, which makes it a very safe DIY option. Commonly used under timber floors, in framed walls and above flat or cathedral ceilings.
This video discusses polyester insulation.
These products are DIY install, if desired.
Expanded Polystyrene Insulation
Manufactured from polystyrene beads, these boards have semi rigid form and are easy to cut and install. They are, however, highly susceptible to water. Some expanded polystyrene insulation also has foil attached, which increases its R-value and its water resistance. Ideally suited for use inside cavity walls and at the edges of concrete slabs. Can be also used under suspended slabs, under timber floors, in framed walls and above cathedral ceilings.
Extruded polystyrene comes in the form of rigid Styrofoam boards. It is easy to cut and, due to its thin profile, can be fitted into tight spaces. It has multiple applications, such as inside cavity and framed walls, above cathedral ceilings, under timber floors, under suspended concrete slabs and at edges of concrete slabs.
Straw bales are DIY install, if desired, though some knowledge/training is required and help from an experienced straw bale builder is certainly an advantage. This is not just an isolated insulation technique, but a whole building process. You would also need to check for any government regulations on this kind of construction.
While not a very common option, straw bales have a very high R-value (which varies depending on the type, thickness and compression of the bales), especially combined with the usual adobe coating, so could be an option to consider if you don't mind trying something a little 'outside the box'. They are also a very environmentally friendly option.
Straw bales are really only an option for those building a home, or adding a room or wing, and take a willingness to deviate from the traditional building mindset.
Strawbale homes can be quite flexible in design, attractive and can be a good option for those who are interested in really trying to lower their 'ecological footprint'.
As an example of the use of straw bales to construct and insulate buildings, we can look at the luxury eco villas built on Rawnsley Park station. Station owner Tony Smith chose straw bales for his eco villa construction, due to their very high R-values and their eco-friendly aspects, which complemented many of the other environmental techniques he was applying in their construction and operation. They certainly prove that this technique can be applied to create truly beautiful constructions.
Strawbale Eco Villa Construction.
Completed Eco Villa Interior.
The video below covers a few of the reasons to consider using straw bales.
This video will give you a bit of an idea of what strawbale building is like.
There's lots of info on strawbale building on the internet!
Don't forget that insulation is only one aspect of controlling the temperature in your home.
A few other things to consider are:
- Block places where air can leak, in or out, such as under doors, window frames, chimneys, air con ducts etc.
- Window films, double glazing etc can help.
- Curtains and blinds can help stop the loss of heat/cool.
- Outside blinds or shade-cloth can help protect windows and walls from overheating.
- Plant trees for shade along walls that get the direct sun. Using deciduous trees means that when the leaves fall during the cooler months, the sun can then be allowed to help warm the walls.
- Use windows effectively to help the flow of cooling air into your home in the evening.
- Consider installing floor level vents (closable) to being cool air from under the house inside.
- Close off areas not in use and heat/cool the areas where you are at the time.