Internal Wall Insulation Buyer's Guide
Why Do You Need Internal Wall Insulation?
Wall insulation plays a vital role in the habitability of your home. It keeps the heat in, in the winter and the traps cooler air inside in the summer. Add to that its efficient energy boosting properties, saving you money on your energy bills annually, you can see why insulation is so important for your home.
If you need to renovate your home or install new insulation, you’ll probably be wondering what the best type of insulation to buy is. There are many to choose from, each with different strengths. We’ve put together this comprehensive guide to provide answers to all of your questions around insulation.
Most Popular Types of Internal Wall Insulation
With so many types of insulation to choose from, how do you know which one will be best suited for your home?
Below, we take a look at some of the best options available to you and the advantages of each.
Insulation Boards – Used as a means to decrease heat transmission through walls, insulation boards are installed on the interior of walls, floors, and roofs. These panels have excellent thermal efficiency and are a good way to provide insulation in smaller spaces due to their thin, lightweight design. Made from foam plastics, phenolic and wood fibre, insulation panels are easy to install and if you are confident in your ability, you won’t need the services of a professional.
Insulation Batts – Also known as insulation slabs, they are commonly used to insulate walls, ceilings, and floors. Pre-cut to a size that fits between conventionally spaced wall studs, joists and rafters for convenience, slabs can be supplied with an outer coating of paper, foil or fabric for better moisture resistance, fire protection and easier installation. Usually made from Rockwool or fibreglass insulation, batts are a great way to insulate the inside of walls quickly and efficiently.
Multifoil Insulation – Foil insulation is available as a panel or as a roll. This versatile insulation is some of the thinnest you can buy; made from a series of layers, out of efficient insulating materials and foil, the flexible insulation is ideal for use in lofts and smaller spaces. This insulation has been designed to last a very long time; it has a life span of over fifty years. A great choice for cramped spaces, it is slim, easy to install and highly efficient.
Loose fill Insulation – Not usually used as the primary form of insulation for your home. Loose-fill insulation is fantastic as a means to fill in the awkward cracks or gaps in your walls. Great for filling hard-to-reach cavities, loose-fill insulation is ideal for sound and heat suppression and is best used in horizontal applications. Made from a range of materials, loose-fill insulation is usually made from recycled newspaper with fire-retardant mineral coating added to ensure it meets all relevant safety regulations.
Insulated plasterboard – By combining insulation and drylining into one board, this type of insulation saves space and gives you a complete insulation package in one product. You can use any number of installation methods to attach them to your walls and they are perfect for adding to existing walls internally. Typically made from Gyproc or Gypsum coated in thick paper, this cost-effective insulation is available in a wide range of sizes and thicknesses making it a highly versatile solution for sound and heat control.
Types of Walls
Knowing the type of walls you have on your property will help determine the type of insulation that’s best. Older properties will generally not be as well insulated as new ones, and you may have to opt for internal insulation methods if you are unable to reach the inside of your walls.
Stud – These are internal walls that are not load-bearing. Used to partition a room, stud walls are made of timber and lack any real strength to them. Plasterboard sheets will be screwed to a timber frame with a cavity between the boards. Ideal for installing insulation slabs, multifoil and rolls of Rockwool.
Cavity – Most houses built after 1930 have cavity walls. Cavity walls became popular because they provide exceptional insulation potential, with many layers of insulation being installed inside the cavity. An easy way to tell if you have cavity walls at home is to inspect the brickwork. If the bricks have an even pattern and are laid lengthways for the entirety of the wall, then it is a cavity wall. Another way to determine the type of all is the thickness; cavity walls are generally more than 260mm thick. Rockwool rolls are a great choice for insulating cavity walls as well as foam and loose-fill insulation.
Solid – Usually found in older properties, solid walls are thinner than cavity walls and have inconsistent brick laying patterns. In order to add insulation to solid walls you will need to install it on the inside or outside of the wall. This is because it has no cavity in which to put the insulation, so you will need to either apply it directly to the wall or use timber battens to create a frame and put the insulation on top of it. Use insulation boards or, if the batten structure is deep enough, multifoil and batts.
Prefab – Prefabricated walls were used as a more budget-friendly option for cheap housing decades ago. Usually, you will be able to fit insulation the same way you would with a stud wall, striping back the plasterboard and adding slabs of insulation or multifoil roll.
Things That Might Affect The Type of Insulation You Buy
The type of insulation you buy and the walls you have in your home are the major aspects you will need to consider before making your choice. But there are other things to consider that will help to determine which insulation best suits you and your home.
Age – As discussed above, most solid stone or brick walls used for housing were built before 1920. The main thing to keep in mind when installing insulation onto solid walls is to ensure they remain breathable. This is because retaining the permeability of the wall allows moisture to pass through and not get trapped, which could lead to condensation and water damage. Use a natural insulation material or those with highly permeable properties. We recommend a wood fibre-based insulation.
R-value – This measures the effectiveness of the insulation at resisting the flow of heat. The higher an R-value is, the better the insulation is at stopping heat from moving through it. This means that you should aim for as high an R-value as possible if your home is especially poor at retaining the heat. Any gaps in between the insulation will lower the R-value and allow heat to escape through your walls.
Installation issues – Unless you are confident in your abilities to install the insulation, consider hiring a professional labourer. This will save you time and give you a guarantee if there are any problems with the installation. Improperly installed insulation will have gaps that create easy pathways for heat to escape, hindering its performance. Insulation is very difficult to install without leaving any gaps but with patience and preparation, it is possible to do it yourself.
Damp – During the removal of old insulation you may discover a leak, either through the wall or from a damaged pipe. You will need to get this dealt with before you install your new insulation. This will potentially drive up the cost of your insulation project and lead to compromises needing to be taken in the insulation material used.
Cost – As well as the initial cost of procuring all of your insulation, which will vary depending on its material, R-value and thickness, there are other costs to bear in mind.
If you need to remove the insulation inside cavity walls, you will need to get it done professionally. This is generally calculated at £20 - £23 per square metre. And for disposal of the insulation, you will usually need to get a quote, and this could cost you anywhere up to a few thousand depending on the size of the job.
If hiring labour to install the insulation for you, the average day rate for a tradesperson is £250. This will obviously vary from person to person and in different areas of the country.
And finally, the average cost of insulating your home in the UK is between £1,400 and £10,000. There are factors that will help determine this, such as home size, the age of your home, and the type of insulation used.
There are many things to think about when deciding to replace or install insulation. What we’ve outlined in this article gives you a handy checklist to work your way through, covering every aspect of choosing insulation that will be perfect for your home.