Great British Insulation Scheme update: The Great British Insulation Scheme closed on 31 March 2026. For insulation funding, check the Warm Homes Plan via your local council, or ECO4 (until 31 December 2026) via an obligated supplier.

Energy Company Obligation (ECO4) update: ECO4 is scheduled to end on 31 December 2026. If you may be eligible, start the referral now — applications received close to the deadline may not complete in time.

Loft Insulation Guide: Costs, Savings and How to Install#

Around a quarter of heat lost from an uninsulated home escapes through the roof. Loft insulation is one of the simplest and most cost-effective ways to cut your heating bills and make your home more comfortable. For a complete overview of all insulation types, see our full insulation guide.

Why Insulate Your Loft?#

Heat rises, and without adequate insulation it passes straight through your ceiling and out through the roof. The current Building Regulations recommend a minimum of 270mm of mineral wool insulation in your loft.

Many older homes have little or no loft insulation, while others may have only 100mm or less -- well below the recommended level. Topping up existing insulation is quick, affordable, and highly effective. Proper loft insulation can reduce energy bills by up to 25%, and well-insulated homes often see an increase in property value, making it a smart long-term investment.

Types of Loft Insulation#

Mineral Wool Rolls (Glass or Rock Wool)#

The most common and affordable option. Rolls are laid between and over the joists in your loft. Mineral wool is non-combustible, does not absorb moisture, and is widely available from any DIY store. Cost typically ranges from £300 to £600 for a semi-detached house as of 2026. This is the best choice for most straightforward loft insulation projects.

Blown-Fibre Insulation#

Loose material (cellulose or mineral wool) blown into the loft space using specialist equipment. Ideal for lofts with awkward shapes, limited headroom, or lots of obstructions such as pipes and wiring. This must be installed by a professional but can be more effective than rolls in hard-to-reach areas.

Loose-Fill Insulation#

Made from materials such as cellulose, recycled paper, or vermiculite, loose-fill insulation is poured or blown between joists. It is a good option for topping up existing insulation or filling irregular spaces. Cost is similar to blanket insulation, though professional installation may be needed if you do not have the equipment.

Rigid Insulation Boards#

High-performance boards that provide better insulation per millimetre of thickness. Used when you want to convert a loft into a habitable room or when headroom is limited. More expensive but essential for loft conversions where you need to insulate the rafters rather than the floor.

Sheep's Wool#

A natural, sustainable alternative. Sheep's wool is breathable, can absorb and release moisture without losing its insulating properties, and is pleasant to handle compared to mineral wool.

Reflective Foil Insulation#

Reflective foil insulation works by reflecting radiant heat back into your home. It is a cost-effective supplementary option, often priced lower than other insulation types. While it should not be relied upon as your sole insulation, it can boost the performance of existing loft insulation, particularly in homes where adding more depth is impractical.

Loft Insulation Costs in 2026#

The cost of loft insulation varies based on material, thickness, house size, and whether you do it yourself or hire a professional.

Costs by Scenario#

Factors That Affect Cost#

• House Size: Larger homes require more material. A detached house will cost more than a mid-terrace.
• Insulation Type: Mineral wool is the cheapest; rigid boards and spray foam cost more but offer higher performance per millimetre.
• Thickness: Thicker insulation provides better heat retention but increases material costs.
• Current Insulation Level: If you already have some insulation, topping up is cheaper than starting from scratch.
• Access and Obstructions: Lofts with limited headroom, lots of pipes, or difficult access may require professional blown-fibre installation, adding to cost.
• Regional Variations: Costs can vary across the UK, with urban areas often seeing slightly higher prices due to increased labour costs.

Real-World Example#

A homeowner in Birmingham successfully reduced their annual heating bills by 20% after installing loft insulation with the help of a local grant. By investing £450 in mineral wool insulation and securing a £200 grant, they achieved an annual saving of approximately £150 on their energy bills -- a payback period of under two years.

How to Install Loft Insulation (DIY)#

Installing mineral wool rolls in an accessible loft is a straightforward DIY job. Here is what you need to do.

What You Will Need#

• Mineral wool rolls (enough for 270mm depth)
• Dust mask (FFP3 rated) (opens in new tab)
• Safety goggles
• Protective gloves and long sleeves
• Loft boards or a crawl board
• Utility knife or large scissors
• A torch or loft light

Step-by-Step Process#

1. Clear the loft -- Remove any stored items and ensure you have safe access. Only step on the joists or use crawl boards.

2. Check for hazards -- Look for exposed wiring, water tanks, or signs of damp. Do not cover any electrical cables with insulation without leaving ventilation space.

3. Lay the first layer -- Unroll the mineral wool between the joists, pressing it gently into place. Cut to fit around obstacles. Standard joists are 100mm deep, so the first layer fills the space between them.

4. Lay the second layer -- Roll the next layer at right angles across the top of the joists. This eliminates cold bridges and brings the total depth to 270mm.

5. Insulate the loft hatch -- Cut a piece of insulation to fit the back of the loft hatch and attach it with adhesive or clips. Fit draught-proofing strips around the hatch frame.

6. Insulate pipes and tanks -- Fit pipe lagging (opens in new tab) to any exposed water pipes and an insulation jacket to your hot water cylinder if it does not already have one.

DIY vs Professional Installation#

DIY loft insulation can save you £150--£250 on labour costs and is suitable for most accessible lofts with standard joists. However, professional installation is recommended if:

• Your loft has limited headroom or difficult access
• You need blown-fibre insulation for irregular spaces
• There are hazardous materials (e.g., old asbestos boards) present
• You are not comfortable working at height or handling insulation materials

Professional installation ensures proper coverage, reduces the risk of gaps, and typically comes with a workmanship guarantee. For more detailed guidance on choosing insulation for your home, see our guide to the best insulation for UK homes.

Grants and Financial Support#

Loft insulation may be available free or at a reduced cost through government schemes, particularly if you receive certain benefits or have a low household income.

ECO4 Scheme#

The Energy Company Obligation (ECO4) scheme requires large energy suppliers to fund insulation measures for eligible households. For a detailed walkthrough, see our guide on how to apply for ECO4 grants. Contact your energy supplier to check whether you qualify.

Great British Insulation Scheme#

This newer scheme targets homes in the least energy-efficient council tax bands (D to G in England and Scotland). It provides funding for insulation measures regardless of household income in some cases. Learn more in our guide to the Great British Insulation Scheme. You can also explore all available funding options in our home insulation grants guide.

Local Authority Schemes#

Some local councils offer additional grants and support for loft insulation. Contact your local council's housing or energy team to find out what is available in your area. Eligibility often depends on income, property type, and existing insulation levels.

For step-by-step guidance on applying for insulation grants, see our article on how to apply for insulation grants.

Frequently Asked Questions#

Practical Next Steps#

1. Check Your Current Insulation: Measure the depth and type of insulation currently in your loft. If it is under 270mm, topping up is worthwhile.
2. Get Quotes: Contact local insulation providers for quotes. Ensure they are reputable and offer guarantees on their work.
3. Check Grant Eligibility: Use the grant checker above or review eligibility criteria to see if you qualify for financial assistance.
4. Choose Your Approach: Decide between DIY and professional installation based on your loft's accessibility and your confidence level.

Sources#

• Energy Saving Trust: Loft Insulation
• GOV.UK: Home Energy Grants
• Ofgem: Energy Market Consumer Advice