In this article

What is home insulation?

What is heat loss in the home?

The benefits of insulation

The different types of insulation materials

Where to install insulation and how to choose the best type

How much does home insulation cost?

How much does home insulation save on annual energy bills? 

Are Government grants available to help with the cost?  

A well-insulated home can provide year-round comfort, help increase energy efficiency and save on heating bills by ensuring the amount of heat the home loses is kept to a minimum. Insulation keeps the home warm when heat is needed most. With various options available ranging from solid wall over cavity to loft insulation, it can seem quite daunting when considering what type of insulation to install, so we’re here to help and give you the essential info to make an informed decision. 

Our handy guide is designed to help you choose the best insulation for a home, give an overview of the different materials and types, as well as looking at the cost benefits and how much insulation can save you on heating bills. 

What is home insulation?

Put simply, insulation is any type of material that is used to insulate something, in this case, the home. Home insulation covers various materials that can be installed in different areas of the home such as the loft and walls, this reduces heat loss by creating a barrier between the inside of the home, and the outside air. Insulation helps to maintain the desired temperature set on the thermostat and adds an additional layer to keep heat in the home – almost like a blanket. 

Home insulation is essential for keeping you warm in the winter, maintaining comfort in the home and reducing heat loss. Without adequate insulation the home can experience a great deal of heat loss, with heat mainly escaping through areas such as the roof and walls. If the home is poorly insulated, it will make it much harder to heat and cost much more to heat. You’d be surprised to find out how much harder heating systems must work to reach the desired temperature. 

What is heat loss in the home?

Heat loss refers to the total transfer or loss of heat that occurs when heat from the inside of the home is transferred and lost to the outside of the home, escaping through areas such as windows, doors, walls and roof. Heat loss is typically measured in either kilowatts (kW) or British Thermal Units (BTUs), and heat can escape the home in several different ways:

  • Conduction: The transfer of heat through a solid material. In the home this will be heat transferred from the inside of the home to the outside. Most commonly this happens through the windows, external walls, floor and roof. 

  • Convection: The process in which heat is lost by either warm air leaking to the outside, when doors or windows are open, or by cold air coming into the home through poor insulation, or cracks or openings in walls, windows and doors. 

  • Radiation: The transfer of heat from warmer to colder objects. For example, if a radiator is running next to a poorly insulated external wall, heat loss will occur and escape through that wall.  

  • Air: Draughts are another key part of heat loss in the home. Cold air can come into the home through gaps in windows and doors, so ensuring good draught exclusion is key.  

The level of heat loss the home experiences plays a big part in its overall energy efficiency and ensuring less heat loss is the best way to keep energy bills low and reduce carbon emissions at the same time. If you’ve got a copy of your home’s Energy Performance Certificate, you may see insulation listed as a recommended improvement. For example, if your loft is poorly insulated, the home can lose as much as 25% of its heat through the roof.1

The benefits of home insulation 

Installing good insulation in the home can have many benefits, financial as well as environmental ones. It can help to reduce annual heating bills and cut your carbon footprint.

  • Good insulation will provide a high level of comfort in the home, all year round. It reduces heat loss in the winter, helps keep you warm and makes it much easier to achieve the desired temperature even in the coldest weather. It also protects against excess heat gains in the summer months, helping keep your home cool.  

  • As well as keeping you warm and comfortable, good insulation also helps to save on energy bills, providing great financial benefits. For example, installing solid wall insulation in the home could save you as much as £415 on your annual energy bill.2
  • When properly installed, insulation can have great soundproofing benefits in the home. It acts as a sound absorber and reduces the amount of noise that travels within the home, from room to room. Insulation can also reduce noise from outside, particularly if you live near a flight path, or a busy road.  

  • Insulation also has great environmental benefits and is one of the steps you can take to combat climate and reduce carbon footprint. A well-insulated home means the heating system installed doesn’t have to work as hard, or run for as long, reducing the amount of fossil fuels burned to heat the home. To give you an idea, a detached home installing loft insulation can expect to save up to 1 ton of carbon dioxide emissions each year, the equivalent of burning 30 barrels of oil.3
  • Installing in the home can be easy and done by the homeowner themselves as an easy DIY job, without any specialist equipment required. This keeps costs down and helps to maximise potential return on investment. Some types of insulation do require a specialist installer, as we will explain later.  

  • Good insulation in the home also opens the opportunity to install further measures to cut your energy bills and carbon footprint. For example, if you’re considering installing a renewable heating system such as an air source heat pump or hybrid heating, then good insulation is a must.  

The different types of home insulation materials

Within the home you will typically find that insulation is installed in the loft, walls or floors and comes installed as one of the following types:  

  • Matting: Sometimes called quilt or blanket insulation. This is one of the most common ways to insulate a loft and can be done DIY, but it is also used to insulate floors and walls. It is sold in rolls and usually made from glass fibre, rock fibre or sheep wool. It comes in different thicknesses and flexibilities.  

  • Loose-fill: This is sold in bags and then poured out for use. Made from cellulose fibre, mineral wool, cork granules or vermiculite, it can be perfect for those harder to reach areas and corners of the loft.  

  • Rigid insulation boards: This type of insulation can be used for ceilings, walls and floors. It’s usually made from polystyrene, or polyurethane. It’s worth noting that this material must be cut to size before fitting, so requires a professional, but once installed it provides a great level of insulation.  

  • Blown insulation: As with insulation boards, this type must be installed by a professional. The insulation is made from mineral wood or recycled newspapers and can be used to insulate walls or lofts, by being blown into the area where insulation is needed. 

Where to install insulation and how to choose the best type 

It can sometimes seem a little daunting to decide on the best suited material for the home, and which areas to insulate. With every home being built a little differently you want to ensure you make an informed decision and ensure the best results for increased energy efficiency. Here are some of the things to consider when deciding what type of insulation to go for. 

Loft insulation 

A loft can be the source of serious heat loss in the home, with a quarter of heat being lost through an uninsulated one. Fortunately, insulating a loft has a long lifespan of typically 40 years, and could save you up to £275 per year on your energy bills. Provided you have no underlying damp problems and want to install your insulation in the joists of the roof for storage only, then this can usually be done as a DIY job. If you would like to use the loft as living space, then you should consult a professional. The materials that would typically be used include matting and loose fill. 

Cavity wall insulation 

A typical home will have either a solid wall, or cavity wall. With cavity wall there is a small gap between the outer wall, and inner wall of the home, known as the cavity. Insulation is pumped into the gap, resulting in greater insulation and less heat loss. Cavity wall insulation needs to be done by a professional using specialist equipment, so this type isn’t suitable for a DIY job. 

Solid wall insulation 

Much older properties may use a solid wall construction, which can experience much greater heat loss as they have no cavity or gaps, with only one layer between the inside and outside air. Solid walls can be insulated both internally and externally. Internal wall insulation uses solid boards which are attached to the internal walls, or an additional stud wall is created to place matting based material such as sheep's wool. This is the cheaper option for wall insulation.  

External insulation on solid walls involves applying boards, which are held in place by reinforcing mesh and render, a cladding is then sometimes placed over the original brickwork. This is the more expensive route for wall insulation and does sometimes require planning permission if it changes the outside appearance of a property. 

Floor insulation 

This type involves an insulating material beneath the floorboards on the ground floor of the home. It stops draughts coming into the home through the floor and comes with expected energy bill savings of up to £75 per year. Floor insulation can also involve sealing gaps between the skirting boards and floors. 

Draught proofing & exclusion 

Draught proofing is another option that can be used to prevent heat loss in the home. Simply put, draught proofing involves blocking up any non-essential & unwanted gaps that let cold air escape. One simple example of draught proofing is installing a letterbox flap to prevent any draughts coming in, but draught proofing can also be installed in places such as windows, and floorboards. Draught proofing can be done DIY, or an installer can carry out the work. 

Our tips to planning an insulation install 

Homeowners have two options when installing insulation in the home. They can either do it themselves or they can get quotes from professional installers. If you’re going down the DIY route, you will need to decide yourself on the best material to use for each area of the home including loft, wall and floor. 

Insulation comes in a variety of thicknesses with the thicker materials typically indicating less heat loss in the home, so it’s important to decide which thickness will provide adequate insulation. 

To help with this, all insulation comes complete with a Lamba or ‘K value’ which you should always check. This measures the thermal conductivity and will be listed in the product information. The lower the value, the less heat loss you will experience with the material. It’s worth noting that the thickness of the material isn’t always key. Thinner materials can have a lower Lamba value, and are therefore more efficient, so always double check.  

Other key points to look out for when taking the DIY route include checking with manufacturers for free samples of insulation material, making sure the material is easy to install, with no specialist skill or experience needed and once installed, making sure the seal is airtight to prevent any unnecessary heat loss. 

Ultimately, choosing the right product for insulation does come down to the specific requirements of the property, so it’s impossible to recommend a one-size-fits-all solution. But we hope this has given you a better idea of the different areas of the home that need to be considered. 

How much does home insulation cost? 

As you’ve seen, there are many methods and materials available to insulate the home, and some great reasons to do it. Prices will vary depending on the size of your home, the materials used, and the area being insulated. Here is a rough idea of what to expect.4

Loft insulation 

Insulating the loft can be very cost effective, and you will typically be able to carry out the work yourself for around £100, depending on the size of your home. While it is relatively easy, if you prefer to hire a professional this will push your costs up to between £285 for a mid-terraced house and £395 for a detached house, when factoring in labour fees.   

Cavity wall insulation 

Because cavity wall insulation needs to be installed by a professional, you can expect slightly higher costs than loft insulation. A small flat will cost around £345 to insulate, whereas a detached home will cost around £600. 

Solid wall insulation 

Solid wall insulation can be quite expensive to install, therefore homeowners often combine the installation with other home improvement works such as having a new kitchen installed, to save on labour costs and call-out fees. Typical prices for a semi-detached house will be around £10,000 for external wall, and £8,000 for internal wall insulation.  

Floor insulation 

A typical installation will cost between £520 and £1,300. It is worth noting that some of this work can be done by yourself to keep costs down, such as sealing gaps between skirting boards and floors, which bring in draughts.

How much does home insulation save on annual energy bills? 

Insulation is a great way to achieve greater comfort in the home, but it can also help you to make big savings on your energy bills. Having a better insulated home means it loses less heat, so you’ll likely turn your heating on less. To give you an idea, loft insulation could save you up to £215 per year, insulating cavity walls up to £245, and for solid walls, savings range between £115 and £415.5

With these annual savings in mind, and considering the initial cost of installing insulation, it is likely that you will recoup your costs within a couple of years for most types.

Are Government grants available to help with the cost? 

Up until March 2021 the Government offered heating and home improvement grants to help with the installation costs of different works in the home, aimed at increasing energy efficiency. This was known as the Green Homes Grant and could have been used towards the cost of insulation. While this has now been withdrawn, you can still receive Government help towards install costs with the Energy Company Obligation (ECO). The scheme is means tested and there are some criteria to meet to receive the funding, such as receiving specific benefits, so we recommend you follow the link above for more information.

Maximise savings by switching energy supplier 

As well as benefiting from the increased savings of a well-insulated home, you could also consider switching energy supplier to maximise these savings. At Igloo Energy our customers save up to £170 per year on average when they join us. We offer one competitive variable rate tariff and when combined with any savings from improved insulation, annual energy bills can be reduced even further.

1 Source: Energy Saving Trust

2 Source: Which?

3 Source: Energy Saving Trust

4 All prices quoted below feature information provided by the Energy Saving Trust

5 Source: Energy Saving Trust