Published: 25 June 2026
What is home insulation and why do you need it?
If you're a homeowner looking to keep your home warm and cut your energy bills, insulation is one of the most effective ways to do it. It works by slowing heat transfer, trapping warmth inside during winter and keeping your home cooler in summer.
This guide covers the main types of insulation, typical costs and available grants to help you reduce heat loss and save money.
What types of insulation are available for walls, lofts and roofs?
Your home loses heat through several key areas: walls (both cavity and solid), loft and roof, and floors. The right insulation depends on your property type and age.
Here are the main insulation types:
- Cavity wall insulation fills the gap between your external and internal walls with foam, beads or mineral wool.
- Solid wall insulation uses rigid boards or external cladding to insulate older properties without cavities.
- Loft insulation typically uses mineral wool rolls or boards laid between and over joists.
- Spray foam insulation expands to fill awkward spaces like roof voids or hard-to-reach areas.
- Floor insulation can be fitted beneath floorboards or as rigid boards in newer builds.
To help you choose the right option, mineral wool works well for loft and roof spaces, rigid boards suit solid walls and floors, and spray foam is ideal for hard-to-reach roof areas and cavities.
How much does home insulation cost and what grants can help?
Insulation costs vary depending on your property size and the type of work needed. Loft insulation typically costs the least, while cavity wall insulation goes for more. External wall insulation is the most expensive, because it's more complex and covers the entire outside of your property.
The good news is you might not have to pay the full amount. Government grant ‘The Energy Company Obligation’ (ECO) is valid until December 2026, and can cover part or all of the cost for eligible households. Eligibility usually depends on your income, benefits status and property type, so it's worth checking whether you qualify.
Is home insulation worth it?
Absolutely. Proper home insulation can save you hundreds of pounds a year on energy bills, especially with rising energy costs. You'll notice better comfort too, as it’ll help make your home warmer in winter, cooler in summer. Plus, you're reducing your carbon footprint and helping the environment. Well-insulated homes often see a boost in property value as well, since buyers increasingly look for energy-efficient homes with lower running costs.
Can you get free home insulation?
Yes, if you're eligible. The ECO4 grant can cover some or all of your insulation costs, although eligibility usually depends on your income, benefits you receive, or your home's energy rating. Energy suppliers are obliged to help fund improvements for qualifying households. Availability and criteria vary by region and supplier, so it's worth checking with your energy provider or local authority.
How long does home insulation last?
Loft insulation can last 40 years or more if installed properly, and cavity wall insulation has a similarly long lifespan. The materials used are durable and require little maintenance. That said, if your insulation is decades old or you're unsure of its condition, it's worth getting a professional assessment. Pairing insulation with draught-proofing can extend its effectiveness and keep your home efficient for years to come.