For maximum impact and savings, prioritise your home insulation in this order: first, seal all draughts around windows, doors, and loft hatches. Second, ensure your loft has at least 270mm of insulation. Third, consider insulating the cavity or solid walls. This “fabric first” approach tackles the biggest heat losses most cost-effectively.
Is your home losing heat faster than you can heat it? Rising energy bills and cold indoor temperatures are frustrating many UK homeowners. The good news is that you do not need to spend a fortune to make a real difference. Simple and affordable home insulation improvements can slash your heat loss, reduce your bills, and make your house consistently cosy.
This guide gives you a clear, practical roadmap. We will start with the quick wins you can do this weekend, then explore the bigger projects, and finally explain the current funding landscape for 2026. You will learn how to keep your warmth where it belongs.
How Heat Escapes Your Home: Know Your Weak Spots
Before you start, it helps to understand how heat moves. Warm air naturally rises and will escape through any available gap, moving from areas of high temperature to low temperature. In a typical uninsulated UK home, a significant percentage of your paid-for heat is lost through the roof and walls.
Your loft or roof is often the primary escape route, accounting for around a quarter of heat loss. Uninsulated walls are another major culprit, responsible for about a third of lost warmth. However, before addressing these larger areas, you must tackle draughts. These uncontrolled air leaks undermine even the best insulation, letting cold air in and warm air out through countless small gaps.
A strategic approach targets the biggest losses first for the best return on your effort and money. This is known as a “fabric first” method, which forms the basis of the following sections.
Quick Wins: DIY Draught-Proofing Your Home
Draught-proofing is the most cost-effective insulation job you can do. It requires minimal investment and basic DIY skills but delivers immediate comfort and savings. The goal is to seal the unintentional gaps that let air flow freely, while preserving essential ventilation for things like boilers and moisture control.
Common draught sources include windows, doors, loft hatches, and where pipes or cables enter your home. Here is how to tackle them.
- Windows and Doors: For casement windows and doors, use self-adhesive foam or rubber draught-excluder strips around the frame. For sliding sash windows, brush seals are more effective. Fit a draught-excluding brush or flap to the bottom of exterior doors.
- Loft Hatch: Seal the edges of the hatch with draught-excluding tape and consider fixing an insulated panel to its top side.
- Other Gaps: Use flexible sealant or decorator’s caulk to fill gaps around skirting boards and between floorboards. Seal around pipework where it enters the house using appropriate fillers like silicone mastic or expanding foam.
Crucial Safety Note: Never block or cover intentional ventilation. This includes boiler flues, air bricks (which prevent damp), and the trickle vents on modern windows. Blocking these can create dangerous fumes and serious damp problems.
Loft Insulation: Your Most Important Project
After stopping draughts, insulating your loft should be your top priority. Because heat rises, an uninsulated loft can waste up to 25% of your heating effort. The current recommended depth for mineral wool insulation is 270mm. Many older homes have only 100mm, so a top-up can yield great savings.
If your loft is easily accessible, not a flat roof, and free from damp, topping up insulation can be a DIY project. You lay the first layer between the wooden joists and a second layer over them at right angles to reach the required depth. However, if your loft is used for storage or you have a flat roof, the job becomes more complex and requires professional assessment.
The savings are substantial. For a semi-detached house, upgrading from no insulation to 270mm can save around £270 per year on energy bills. Even topping up from 120mm can save an extra £25-£40 annually.
Wall Insulation: Stopping Major Heat Loss
Walls represent the largest surface area of your home. The right solution depends entirely on whether you have cavity walls or solid walls.
Cavity Wall Insulation is suitable for most homes built after the 1920s. A professional installer drills small holes in the outer wall and fills the gap with insulating material. It is a relatively quick, non-disruptive process. For a semi-detached house, it can save approximately £235 per year.
Solid Wall Insulation is needed for older, pre-1920 properties. You have two choices: Internal Wall Insulation (fixing insulated boards to the inside walls, which is disruptive and reduces room size slightly) or External Wall Insulation (adding insulated render to the outside, which renews the exterior but is a major project). Both are significant investments but dramatically improve comfort and efficiency.
Floor and Pipe Insulation
While less critical than roofs and walls, insulating suspended timber floors and water pipes provides extra benefits and protection.
If you have floorboards on joists with a cellar or crawl space below, you can often fit insulation boards between the joists from underneath. Insulating your hot water cylinder and the pipes in your loft with a lagging jacket and foam tubing is cheap, easy, and vital. It keeps your water hotter for longer and, most importantly, prevents pipes from freezing and bursting in winter.
Professional Installation vs. DIY: How to Choose
Knowing when to call a professional is key to a safe, effective, and long-lasting result.
| Job Type | Suitable for DIY? | When to Hire a Pro |
|---|---|---|
| Draught-Proofing | Yes. Sealing windows, doors, and gaps is straightforward. | For complex window types or if you are unsure about ventilation. |
| Loft Insulation (Top-Up) | Potentially. If access is easy, and it’s a simple cold loft. | For flat roofs, lofts with damp, or if you want to board for storage. |
| Cavity Wall Insulation | No. This always requires a certified specialist. | For any cavity wall assessment and installation. |
| Solid Wall Insulation | No. This is a major technical building project. | For both internal and external solid wall insulation systems. |
Always use a TrustMark-registered installer for professional work. This government-endorsed quality scheme ensures they meet strict standards. Get at least three written quotes and ask for references.
Understanding Grants and Funding for 2026
Financial help for insulation is in a period of transition in early 2026. The Great British Insulation Scheme (GBIS), which offered free or discounted insulation, closed to new applicants at the end of January 2026. The separate Energy Company Obligation (ECO4) scheme, which targets low-income and vulnerable households, continues to operate until March 2026.
Looking ahead, the government has announced the Warm Homes Plan. This new initiative, set to begin after April 2025, aims to provide a unified framework for home energy upgrades over several years. While full details are pending, it is expected to offer a mix of grants and loans, prioritising lower-income households and the least energy-efficient homes (typically those with an EPC rating of D or below).
Your first step is to check with your energy supplier or the government’s energy advice services to see if you qualify for any remaining support under ECO4 or local authority schemes.
When Insulation Might Not Be Your First Step
Insulation is highly effective, but there are circumstances where you must address other issues first. The most critical is existing dampness. Installing insulation on a damp wall or in a wet loft will trap moisture, leading to mould, rot, and structural damage. Any damp problems must be fully investigated and resolved by a professional before insulating.
Similarly, if your home has severely inadequate ventilation (e.g., no extractor fans in bathrooms, blocked air bricks), adding insulation without improving ventilation can lead to poor indoor air quality and condensation issues. A holistic view of your home’s environment is essential.
FAQs
What is the very first thing I should do to make my home warmer?
Start with draught-proofing. Seal around windows, doors, and your loft hatch. This is a low-cost, high-impact task that you can do immediately to feel a real difference in comfort.
I have some loft insulation already. Is it enough?
Probably not. The current recommended depth is 270mm. Use a ruler to check. If you can still see the tops of the wooden joists, you need to add more. Topping up from 120mm to 270mm is a cost-effective upgrade.
Are there any free insulation grants available in 2026?
The landscape has changed recently. The major GBIS scheme is now closed. However, the ECO4 scheme continues for eligible households until March 2026, and the new Warm Homes Plan is expected to launch next. Contact your energy supplier or Home Energy Scotland (or equivalent in your nation) for the most current advice.
Can insulation cause damp or mould?
Only if installed incorrectly. Proper insulation, coupled with adequate ventilation, will reduce condensation. Problems occur if insulation blocks ventilation points (like eaves vents in a loft) or is fitted against a damp wall. Always ensure moisture can escape.
Is it worth insulating an old, solid-wall house?
Yes, absolutely. While it is a bigger investment, solid wall insulation (internal or external) transforms the comfort and energy efficiency of older properties. It tackles the single biggest cause of heat loss in these homes and can drastically reduce your bills.
