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Insulating your home is one of the most effective ways to reduce heat loss, lower energy bills, and decrease your carbon footprint. This guide provides an overview of various insulation options, including internal and external wall insulation, cavity wall insulation, underfloor insulation, and roof and loft insulation.

Each type has its unique benefits, from saving on energy costs to improving your home’s comfort and appearance. Whether you’re dealing with an older property or looking to improve an already insulated home, the right insulation can make a significant difference. This guide also offers tips on choosing certified installers and exploring potential funding options to make your home more energy-efficient.

Internal and External Wall Insulation

Solid wall insulation can help reduce heat loss and make your home more energy efficient, especially if your house was built before the 1920’s and lacks cavity walls. 

Types of Solid Wall Insulation

1. Internal Wall Insulation:
   • Rigid insulation boards or stud walls are installed inside the house.
   • Rigid boards are thinner but require smooth walls.
   • Stud walls are thicker but sturdy enough for heavy fixtures like radiators.
   • Prepping involves leveling uneven walls and removing skirting boards, radiators, and other fittings.
   • Professional installation is recommended for optimal results.

2. External Wall Insulation:
   • Insulation material is fixed to the outside of walls, then covered with protective render or cladding.
   • Can improve your home’s appearance with various finishes, such as textured, brick-like, or painted surfaces.
   • Requires extending features like window sills or pipework to fit the new wall depth.
   • Suitable for improving energy efficiency while maintaining indoor space.

Key Benefits

• Reduces heat loss, and can help cut energy bills by £240 and save 650kg CO2/year for a detached bungalow*.
• Can improve your home’s weatherproofing and aesthetics.
• Improved energy efficiency – insulation reduces the amount of heat lost through walls, which in turn can reduce energy bills and carbon emissions. 

Things to Consider

• Damp issues must be resolved before insulation work begins.
• Permissions may be needed for listed buildings or in conservation areas.
• Choose an experienced  installer, and get quotes from multiple professionals to compare costs and services.  
• The National Insulation Association (NIA) exists to promote a more energy-efficient built environment and their members are fully committed to maintaining and raising standards within the insulation industry. https://www.nia-uk.org/find-an-installer/  
•  The Installation Assurance Authority is the industry body that provides assurance framework under a single compliance platform and covers consumer protection, technical guidance, Certification, Competent Persons Scheme (CPS), installer surveillance, monitoring, training and carding.  https://www.theiaa.co.uk/ 
• Funding may be available for insulation. See available funding here.

Both internal and external options have unique advantages and are best suited to different scenarios. 

Accredited Providers 

When starting your journey to making home improvements, it is important to choose a certified installer when installing a renewable energy system. You can read more about choosing the right installer here.

*Energy Saving Trust October 2024.

Cavity Wall Insulation 

Approximately one-third of the heat in an uninsulated home is lost through the walls. Properly insulating cavity walls can significantly reduce energy loss and lower your heating costs.

Homes built from the 1990s onward typically have wall insulation to retain heat. However, if your home was built before the 1990s, it may lack wall insulation entirely.

The easiest way to investigate if your home has a cavity is to examine and measure the width of a wall. If a brick wall is more than 260 mm thick then it probably has a cavity. If you are unsure please consult with a registered installer who will carry out a borescope inspection where they can drill a small hole to see if your walls are hollow or insulated.

How are the cavities insulated? 

Most cavity walls can be insulated by injecting insulation material into the cavity from outside. Your accredited provider will drill holes around 22 mm in size at intervals of around 1 meter apart in the outside of your home. The insulation is then blown into the cavity via the holes using special equipment. Once complete the holes in the brickwork will be filled and repaired. 

Is cavity wall insulation right for your home? 

Your home could be suitable for cavity insulation if it meets the following –

• Walls have unfilled cavities at least 50mm wide.
• Cavities are clear of rubble.
• The brickwork is in good condition.
• Walls are not exposed to heavy rain or flooding risks.

An installer will survey your home to confirm suitability and may use mineral wool or polystyrene beads for insulation. If you have any damp issues, the walls should not be installed until the problem has been resolved. 

Benefits

• Save money – It can help cut energy bills by £180 and save 490kg CO2/year for a detached bungalow*.
• Improved energy efficiency – insulation reduces the amount of heat lost through walls, which in turn can reduce energy bills and carbon emissions. 

Underfloor Insulation

Ground floor insulation helps reduce heat loss and prevent draughts, making your home warmer and more energy-efficient. It can cut heating bills and lower carbon emissions. 

Types of Floors and Insulation:

1. Suspended Timber Floors (the easiest way to find out if you have a suspended floor is to go outside and check for air vents or ventilation bricks – if you see them, it is likely you will have a suspended floor, or perform a ‘heel drop test – if you hear the floor give or furniture reverberates):
   • Insulated by lifting floorboards and laying mineral wool or other insulation between the joists.
   • Requires proper ventilation to avoid damp issues.
2. Solid Concrete Floors:
   • Insulated by adding rigid insulation boards on top of a damp-proof membrane, followed by a new floor layer.

Benefits:

• Saves around £120 per year on energy bills by reducing heat loss through the ground and save 330kg CO2/year for a detached bungalow*.
• Improved energy efficiency – insulation reduces the amount of heat lost through walls, which in turn can reduce energy bills and carbon emissions. 
• Sealing gaps between floorboards and skirting can further prevent draughts.

Quick Fixes:

• Use rugs and draught-proofing sealants for immediate improvements.
• Seal gaps between floorboards and skirting boards to reduce draughts easily. 

Things to Consider

• Damp issues must be resolved before insulation work begins.
• Permissions may be needed for listed buildings or in conservation areas.
• Choose an experienced installer, and get quotes from multiple professionals to compare costs and services.
• Funding may be available for insulation. See available funding here.

Accredited Providers

When starting your journey to making home improvements, it is important to choose a certified installer when installing a renewable energy system. You can read more about choosing the right installer here.

*Energy Saving Trust October 2024.

Roof and Loft Insulation

Insulating your roof or loft is a cost-effective way to better your home’s energy efficiency and comfort. The recommended thickness for insulation is 270mm. Typically the first layer of insulation is laid between the joists and then another layer is laid at right angles to the joists to make the insulation up to the required depth. 

Why Insulate Your Roof?

• Without insulation, about 25% of your home’s heat escapes through the roof. Through proper insulation you can reduce your heating bills which offers long term savings. 
• Reducing energy consumption lowers your carbon footprint, contributing to environmental conservation.

Benefits:

• Maintains a consistent indoor temperature, keeping your home warmer in winter and cooler in summer.
• Insulation is a one-time investment that pays for itself multiple times over its 40-year lifespan. 
• Going from no insulation to 270mm of loft insulation could save around £370 per year on energy bills by reducing heat loss through the the roof and save 1000kg CO2/year for a detached bungalow*.
• Increasing your already existing insulation to 270mm could save around £35 per year an energy bills and save 95kg CO2/year for a detached bungalow*.

Quick Fixes:

• Draught Proofing –  Seal gaps around loft hatches, pipes, and electrical fittings to prevent heat loss.
• Loft Hatch Insulation – Insulate and draught-proof the loft hatch to minimize heat escape.
• Pipes and Water Tanks – Insulate exposed pipes and water tanks in the loft to prevent heat loss and freezing.

Things to Consider:

• Ensure your loft is accessible and free from dampness before installation. As insulation stops heat from escaping, it will make your loft cooler. Which could in turn introduce or worsen any existing damp or condensation problems, therefore it is important to keep in mind you may need to increase ventilation. 
• Maintain adequate ventilation to prevent condensation and damp issues.
• Care must be taken to avoid layering over electric cable runs which will have a current rating assuming open air dissipation; installers also need to notify homeowners if the insulation is on top of downlighters because the lights should be replaced with fire-rated units if thermal ventilation is restricted or safety downlight covers. 
• Funding may be available for insulation. See available funding here.

Accredited Providers

When starting your journey to making home improvements, it is important to choose a certified installer when installing a renewable energy system. You can read more about choosing the right installer here.

*Energy Saving Trust October 2024.

Tanks, Pipes and Radiators

Insulating your water tank and radiators is a quick and easy way to save money on your bills. Insulating behind radiators helps keep your home warmer and insulating your hot water tank helps keep the water hotter for longer. 

Benefits: 

• Easy installation that can usually be done by yourself
• Saves money on energy bills 
• Keeps your home warmer for longer and for less. 

Insulating a hot water tank: 

• Installing a hot water cylinder jacket costs around £22, and is a straightforward job if you follow the manufacturer instructions. 
• By insulating your cylinder you reduce the amount of heat loss that escapes through the tank, therefore you spend less money heating water up, and the water will stay warmer for longer. 
• You could save £175 per year on energy bills by insulating the hot water tank and save 670kg CO2/year for a detached bungalow*.

*Energy Saving Trust October 2024.

Radiator Reflector Panels 

Radiator reflector panels offer a brilliant, low-cost option (a cut-to-size pack costs around £9) to reduce your energy bills and consumption. You can easily fix them behind your radiators, where they reflect heat back into the room instead of allowing it to escape through an external wall. They are most beneficial when applied to walls where no insulation is already present. 

Remember – you only need to put reflector foil panels behind radiators situated on external walls. 

Insulating Pipes 

Although insulating pipes may not have a huge impact on your energy consumption or bills, insulating pipes can help reduce freezing over winter. When water freezes it expands and this could result in burst or cracked pipes. 

In pipes that transfer warm water around the home, adding some insulation to pipes around the home could save on average £6 per year and will reduce heat loss from the pipes.

Installing insulation in your home is one of the most effective ways to reduce heat loss, lower energy bills, and decrease your carbon footprint.

This page is from our Sustainable Directory.

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