The key numbers on loft insulation in the UK, drawn together from official government and Energy Saving Trust data: how many homes are properly insulated, how much heat escapes through the roof, the depth now recommended, and what insulating typically saves. Every figure is sourced below, and you are welcome to cite this page.
Compiled by Insulation Advice Centre. Last updated: 4 October 2026. We are an independent advice and quote-comparison service; we don't sell or fit insulation.
The roof is one of the biggest single escape routes, and the cheapest to fix.
Source: Energy Saving Trust, typical figures for a gas-heated home. Proportions vary by property type and are indicative, not exact.
Loft insulation is the most common and cost-effective insulation measure in the UK, yet a large share of homes still fall short of the recommended depth. The figures below pull together the most recent official and industry data, with sources listed at the foot of the page. They are free to cite with a link back to this page.
According to the English Housing Survey 2024–25, around 42% of dwellings with a loft had at least 200mm of loft insulation, up from 39% in 2022 and 38% in 2014. Uptake has risen steadily but remains below half, and since the current recommendation is 270mm, even some of that 42% sits short of the modern standard. In other words, the majority of lofts in England are still under-insulated against today's guidance.
Wall insulation has climbed too: 54% of dwellings now have cavity or solid wall insulation, up from 48% in 2014. Walls are the single biggest heat-loss route, so this still leaves a large gap.
The Energy Saving Trust estimates that about a quarter (25%) of the heat in a typical uninsulated home escapes through the roof, with roughly 35% going through the walls and up to 15% through the floor, and the remainder through windows, doors and draughts. Because the roof is both a major escape route and one of the easiest areas to reach, loft insulation gives one of the quickest returns of any home-energy measure.
The recommended depth for mineral-wool loft insulation is 270mm, in line with Part L of the Building Regulations and Energy Saving Trust guidance. This is typically achieved with one layer laid between the ceiling joists and a second layer laid across the top of them to cover the cold bridges. Older homes were often insulated to 100mm or less, which is why so many lofts benefit from a top-up or upgrade. Our guide to loft insulation depth explains how to reach the right total.
Savings depend on the property and the starting point. Energy Saving Trust figures for insulating an uninsulated loft to 270mm suggest a typical annual saving of around £360 for a detached house, £190 for a semi and £140 for a mid-terrace. Topping up an existing layer saves much less, in the region of £17 a year going from 120mm to 270mm, which is why a top-up only makes sense on a loft that is genuinely short of depth. Figures are typical estimates and vary with energy prices. Our loft insulation cost guide breaks the numbers down by house type.
Three reasons come up repeatedly: homes insulated years ago to a lower standard and never topped up; lofts where the insulation has been crushed by boarding or storage; and lofts where a well-meaning top-up blocked the eaves and had to be pulled back. The last two are avoidable, and we cover them in our loft insulation dos and don'ts and loft boarding guides.
The figures on this page are drawn from the following publicly available sources, accessed October 2026:
Citing this page: you are welcome to use these statistics in articles or research. Please credit "Insulation Advice Centre" with a link to this page. If you would like the underlying breakdown or a comment for a piece, contact us at hello@insulationadvicecentre.org.
According to the English Housing Survey 2024-25, around 42% of dwellings with a loft had at least 200mm of loft insulation, up from 39% in 2022 and 38% in 2014. Since the recommended depth is 270mm, even some of that 42% is short of the modern standard, so the majority of lofts in England remain under-insulated against current guidance.
The Energy Saving Trust estimates about 25% of the heat in a typical uninsulated home escapes through the roof, with roughly 35% through the walls and up to 15% through the floor, and the rest through windows, doors and draughts. The roof is both a major escape route and one of the easiest to insulate.
The recommended depth for mineral-wool loft insulation is 270mm, in line with Part L of the Building Regulations and Energy Saving Trust guidance, usually a layer between the joists plus a second layer laid across the top of them. Many older homes were insulated to 100mm or less and benefit from a top-up.
Energy Saving Trust figures for insulating an uninsulated loft to 270mm suggest a typical annual saving of around £360 for a detached house, £190 for a semi and £140 for a mid-terrace. Topping up an existing layer saves far less, around £17 a year from 120mm to 270mm. Figures are typical estimates and vary with energy prices.
If your loft is short of 270mm, boarded over, or you are not sure what is up there, we can give you a straight answer. We don't sell or fit insulation; we recommend what suits your home and pass the job to installers we've vetted. Tell us about your loft and, if you want, we will match you with vetted, accredited installers so you can compare no cost quotes.
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