How much does insulation cost?

Price guide

£300 - £15,000







Low, median and high bar chart distribuiton

How much does insulation cost?

Have you recently noticed your electricity bills going up? You might want to check your home insulation, as it dramatically affects your heating and cooling costs. Insulation comes in many types and forms, but all of it works by occupying dead air spaces or cells to help slow heat flow. This protects the rooms of the house. Without insulation, heat escapes your home through the roof and loft, through the walls, windows, floors, vents and openings. The heating costs during colder seasons will make you feel like your money is literally escaping your home. 

Insulation gives your house resistance to heat flow and helps you manage your heating and cooling expenses. Expect to pay anywhere between £300 to £15,000 for a home insulation project.

What factors affect the cost of insulation?

Insulation comes in various forms and is installed by different methods. Read on to know how these factors affect the overall cost. 

Type of insulation material

Depending on the necessities, there are various insulation options to choose from. Each option offers different benefits and has its own pros and cons. Make sure to ask your contractor for advice regarding the needs of your home.

Blanket insulation is one of the most common types. It comes in rolls with a foil backing. It’s made from glass wool, which is derived from recycled bottles, making it cost-effective. Rock mineral wool insulation is a more solid material compared to blanket insulation. It can also be bought in rolls, and it comes in various thickness options and widths. It’s also resilient to heat and fire.

Sheet loft insulation comes in sheets and is used to insulate the sloping side of the roof. It can be more expensive and energy-intensive to manufacture. Meanwhile, loose-fill insulation is used in blown-in cavity wall insulation. While it’s the easiest one to install using the proper equipment, you still need to hire a professional to make sure it’s installed properly. 

Spray foam insulation costs will depend on the size of your house. It’s typically installed using a foaming agent, then expands and becomes solid as it cures. Structural insulated panels are used in walls, roofs, and floors. They are usually four to eight inches thick and come in various sizes. If you’re building a new property, this may work best for you. Lastly, rigid foam insulation is used when there is a weight that needs support. Its rigidity also helps give acoustic insulation by minimising the sounds passing through walls and raised floors.

Part of the house

The cost for insulation will typically depend on what part of the house needs insulation. Loft insulation involves putting an insulating material over the joists of the loft and filling in the spaces between them with material to help manage the temperature in the rooms below the loft. Loft insulation costs between £300 to £400, making it the most expensive type of insulation.

If you want to make your loft a usable space, you may opt for roof insulation instead. This involves insulating boards under the roof’s pitched slope or spray foam to coat the roof’s underside and the rafters. It may be more expensive, as roof insulation costs range between £400 to £500. Nevertheless, it allows you to use your attic for other functions, so it can still be considered cost-effective. Before you begin with roof installation, you might want first to evaluate if your roof needs ventilation.

Wondering how much conservatory roof insulation costs? Conservatory insulation involves replacing the conservatory roof with a new thermally efficient tiled or solid roof. This will provide you with a room that will keep you safe from scorching weather or the coldest winters. Conservatory insulation costs around £895 to £3,960.

Besides keeping you cool or warm, wall insulation will also help you reduce sounds from the outdoors. There are two types: cavity wall insulation and solid wall insulation. Cavity wall insulation fills up the space between the internal and external layers of brick that form your exterior walls. The contractor will drill holes in the wall where the insulating material will be pumped in. If you opt for this insulation, expect to pay the cavity wall insulation cost of around £200 per two-storey exterior wall.

If you have solid walls, which are single-layered and have no cavity to fill in, you might need to get an interior wall or exterior wall insulation. The layer of insulating material will be added to the external wall and then covered with render. In the case of an internal wall, it will be covered using a plasterboard. External wall insulation costs range from £4,000 to £20,000, depending on the size of your property.

Size of your home

The size of your home will determine the kind and volume of material appropriate for its insulation. The larger the size of your home, the more expensive it may be. 

Location and labour costs

Labour costs can be per hour or project and will most likely depend on where you live. Companies in major cities usually charge higher, but take into account its proximity from your home.

Insulation price list

Not sure how much an external wall or insulated conservatory roof costs? Below is a price comparison table of various insulation projects and the common materials used for each project. 

Insulation project


Price range

Estimate annual savings

Loft insulation

Fibreglass or mineral wool

£300 to £350 

for a 3-bedroom semi-detached house

Up to £180

Cavity wall insulation

Polyurethane foam or fibre material blown in between walls

£450 to £500 

for a 3-bedroom semi-detached house

Up to £140

External solid wall insulation

Expanded polystyrene, mineral wool, or phenolic resin (K5)

£8,500 to £15,000

Up to £490

Internal solid wall insulation

Rigid insulation boards, dry lining, thermal lining, insulated plaster such as plaster and cork

£5,000 to £7,000

Up to £460

Other factors that affect the cost of insulation

Aside from the major factors, additional costs may come up depending on your agreement with your contractor.

  • Mesh - “Panzer Mesh” or two layers of mesh will add around 10% to the overall cost. This is usually used in areas where impacts on the wall can happen, especially if dwellers are into sports, etc.
  • Scaffolding - Some contractors include the price of scaffolding in the overall quote. But if there are areas that are difficult to reach, with restricted access, or with obstacles in the way, it will be an additional charge.
  • Colours and detailing - Depending on your preference, you may want to opt for a darker colour, or you may want to add extra features. This costs hundreds of pounds to the overall price.

Other benefits of insulation

Living in a well-insulated home will bring you and your family comfort, especially in the winter, as it will stop you from getting too cold. In the summer, on the other hand, good insulation will improve the air temperature inside your home as it protects you from outside heat. This saves you from expensive heating and air conditioning systems that may cost thousands of dollars. With this in mind, it also decreases your CO2 emissions from heating or cooling systems, thus helping the earth limit greenhouse emissions.

Aside from temperature, good insulation also blocks outside noise, which can disrupt your rest and sleep, especially when you live near a busy road.  All these advantages make a home appealing to future renters or owners. If you plan to sell or list your home, good insulation is a great way to increase your property value and appeal. 

How to know if you have quality and effective insulation

To evaluate the insulating capability of insulation materials, you can check for the “R-value per inch.” This refers to the resistance of the material against the flow of heat. The higher the R-value, the better the performance.

Below are some questions to guide you as you check your insulation:

  • Was the insulation material applied appropriately in a specific area?
  • Does the insulation material stay in place?
  • Was it installed without gaps, voids, compressions, and low spots?
  • Does it stay dry?

If you answered yes to all four questions, then your insulation will most likely be effective. But keep in mind that it is also possible to “over insulate”, leading to high humidity levels, condensation, and poor air quality. To prevent this, you can hire a trusted installer to do the job.

Insulation helps you live comfortably and cut down electricity costs. If you’re ready to start your home insulation project, put up a task on Airtasker and connect with nearby installers who can provide you with a free quote.

Price guide

£300 - £15,000







Low, median and high bar chart distribuiton

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How do I know which type of insulation to choose?

The type of insulation you need depends on how and where you’ll use it. It will also depend on your budget. For instance, if you want soundproofing to go along with insulation, your best options are fibreglass insulation and blown-in cellulose insulation.

Can I do a DIY project, or should I hire a contractor?

Some insulation materials can be installed as DIY projects, such as mineral wool insulation. However, others require special skills and equipment, such as spray foam insulation. You will need to hire a professional to complete the project. You can consult them regarding the project specifics, and they’ll be able to complete the project faster as well.

How much insulation should I install?

It depends on where you live and how old your home is. Your geographical location will determine the climate that you have in your area. It is important to note that different climates require different insulation R-values. Aside from this, if your house is more than 10 years old, it’s highly likely to require more insulation.

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