Insulating walls in your home is an important step to ensuring you have a well-performing energy efficient house. Depending on the size of your house, and where you live, you may be able to achieve significant savings on your energy bills by insulating internal walls.
There are many different types of insulation, each with their own unique advantages and disadvantages. The right choice for you will depend on the wall material, site conditions, and your budget. For external walls a few of the options include:
Rigid insulation boards are available in pre-cut widths and lengths to suit standard stud and joist spacing. These are fixed to the wall using either adhesive or mechanical fixings. This is one of the most effective options, but it is not suitable for all situations. It may not be a good idea in areas where dampness can be an issue. It is also not suitable for securing heavy objects such as kitchen cabinets or TV brackets to the insulated wall. Special fixings will need to be used, but these can lead to perforations in the vapour barrier.
Another option for insulating internal walls is to use blown-in cellulose or spray foam insulation. Both of these are applied from the outside to existing walls, but they require a professional installer. Blown in cellulose is made from recycled newspapers and small pieces of fibre that are blown into open cavity wall spaces. This type of insulation is a cost effective option for new builds, and it offers an R-value between R-3 and R-5.
Closed cell spray foam is a more expensive alternative to blown in cellulose insulation, but it offers an R-value of up to R-10. It is applied by a professional using a spray gun that mixes a liquid polyurethane with a resin and sprayed into open cavity wall spaces. It is known for its air sealing properties and can help maintain a consistent indoor temperature year round.
Injection foam insulation works the same way as sprayed foam, but it is mixed in situ before application. This means it can be installed in locations where it would not be practical to install sprayed foam, such as inside existing plaster walls. This type of insulation is not as breathable as other alternatives, so it is not recommended for damp areas.
Another option for insulating existing homes without tearing down the drywall is to use RetroFoam. This product is injected directly into the existing cavity wall and expands to fill the space, sealing leaks and blocking gaps. It is a quick and simple process, but it does not offer the same level of R-value as other insulation. It is not ideal for all sites, and it can be difficult to access services such as plumbing or electrical wiring. For this reason, it is generally only suitable for small or medium sized projects. For larger projects a professional installation is more suitable.