Home / Campaigns / The Big Loft Insulation Drive / Costs and savings / Mid-terrace house with 120mm insulation Mid-terrace house with 120mm insulation Annual saving – £25 Professional installation cost – £720 Professional installation payback time – 28.8 years DIY installation cost – £470 DIY installation payback time – 18.8 years Annual CO2 saving – 50kg The recommended depth for mineral wool insulation is 270mm and everyone should aim for this. The insulation you currently have is around 120mm so getting more insulation can still save you money. This is called top-up insulation. A typical mid-terrace house can save £25 per year A typical mid-terrace house can save £25 per year as a result of having top-up loft insulation. The typical cost of getting a professional installer to fit top-up loft insulation in a mid-terrace house is £720. This means the time it takes to pay back this investment in your home would be 28.8 years. The typical cost if you decide to install loft insulation yourself is £470. This means the time it takes to pay back this investment in your home would be 18.8 years. A professional installer can get the job done in as little as an afternoon, or doing it yourself could take just one weekend. If you aren’t sure which is right for you, look at our guide for choosing DIY or professional installation. Top-up loft insulation will immediately make your home feel more cosy, keeping the heat in for longer on cold days. In summer it also helps keep your house cooler when the weather is hot. You will be helping the planet too, by saving 50kg of CO2 emissions every year As loft insulation means you will use less gas to heat your home, you will be helping the planet too, by saving 50kg of CO2 emissions every year. Some people are eligible for government support schemes to help with energy bills and home energy efficiency improvements. This information is based on independent research by Energy Saving Trust. Estimates are based on insulating a gas-heated home, and UK fuel prices in July 2023. The estimated costs for professional installation are unsubsidised and prices will vary. The recommended depth of mineral wool insulation is 270mm, but other materials need different depths. Loft insulation typically lasts for 40 years. This means it should pay for itself many times over in that lifetime. If you rent your home, you will need to discuss installing loft insulation with your landlord. Join the conversation #KeepTheHeat Get involved In partnership with: Disclaimer This information is provided for guidance only. Please see the full disclaimer in our terms and conditions. DIY cost estimates include VAT. Professional installer estimates exclude VAT as this is not applied to insulation services.