Group A · Loft and roof insulation
Loft insulation
Mineral wool laid between and across the joists to 270–300 mm so heat stays in the rooms below.
Price by property type
Loft insulation (new or top-up)
- Mid-terrace£500–£1,000
- Semi / end-terrace£600–£1,300
- Detached£900–£1,800
- Bungalow£900–£2,000
- Flat / block£400–£900top floor
Before grants · updated 11 October 2026 · a survey confirms the final figure.
- Best for
- Lofts with little or no insulation
- Guarantee or standard
- Building Regs Part L; manufacturer data
- Time on site
- Usually a day or less for a typical house loft.
- Typical price
- From £400
What it is
What is loft insulation?
Mineral wool laid between and across the joists to 270–300 mm so heat stays in the rooms below.
Best for: Lofts with little or no insulation.
Build-up
Loft insulation
Cold, ventilated loft
Warm room below
- 1Cross layer laid over the joistsSecond roll laid at right angles
- 2First layer between the joists
- 3Ceiling
Mineral wool to 270–300 mm, with the eaves kept clear for ventilation.
Who it suits
Which homes is loft insulation suitable for?
Is my home suitable?
Pick your property type for a straight answer on loft insulation.
Guidance only — every home is different, and a survey confirms what suits yours.
Houses
- Detached house
- Semi-detached house
- End-of-terrace
- Mid-terrace
- Townhouse
- Mews house and cottage
- Detached bungalow
- Semi and terraced bungalow
- Chalet and dormer bungalow
- Period home
- 1930s home
- Post-war and ex-council house
- Non-traditional / system-built
- Listed building or conservation area
- Farmhouse, barn conversion or rural home
- New build or self-build
Flats and blocks of flats
Commercial and public buildings
Usually suitable Depends — a survey confirms
Not usually suitable for 1 property type
- Park and mobile home — Park and mobile homes need specialist systems, which we arrange through a partner rather than standard measures.
Materials and brands
What we use
Mineral wool rolls between and across joists to 270–300 mm: Knauf Insulation Earthwool (glass mineral wool), Rockwool (rock mineral wool), Superglass, Isover.
Insulation brands we work with
- Knauf Insulation (Earthwool, Supafil blown)
- Rockwool
- Superglass
- Isover
- Kingspan
- Celotex
- Recticel
- Xtratherm
- Steico wood-fibre
- YBS and Actis multifoil
The exact system and brand for your home are confirmed in your written quote.
Heat, bills and EPC
What it does for your heat loss, bills and EPC
Heat rises, so a poorly insulated roof is often the largest single route out for heat. Insulating it lowers the roof's U-value — how easily heat passes through — so the heating runs less and the EPC rating usually improves. The gain is largest where there's little insulation now; topping up a loft that's already reasonably insulated gains less.
See the EPC points and savings for your home in the EPC plannerU-value before and after, typical heat and bill saving, and EPC points — worked out for your property.Price
How much does loft insulation cost?
Prices change with your property type. Pick your column — the quote builder then refines it for your home.
| Measure | Mid-terrace | Semi / end-terrace | Detached | Bungalow | Flat / block |
|---|---|---|---|---|---|
| Loft insulation (new or top-up) | £500–£1,000 | £600–£1,300 | £900–£1,800 | £900–£2,000 | £400–£900top floor |
Indicative ranges for London and the South East, supplied and installed, including VAT, before grants. Updated 11 October 2026. A survey confirms your final price.
0% VAT on energy-saving materials
Insulation, solar panels, batteries and heat pumps installed in homes in Great Britain are zero-rated for VAT until 31 March 2027. Windows and doors are not included.What to expect
Time on site, disruption and approvals
Time on site
Usually a day or less for a typical house loft.
Disruption
Low. We lay crawl boards to work safely and sheet the landing below the hatch, which can get dusty.
Planning and building control
Loft insulation doesn't need planning permission or building control. Re-roofing, flat roof replacement and turning a roof space into a room must meet Building Regulations Part L, and we handle the notification.
Guarantee and standard
Building Regs Part L; manufacturer data. The guarantee and certification for your job are confirmed in writing in your quote.
60-second grant check
Could a grant help pay for it?
Grant eligibility checker
About 60 seconds · plain results: likely, possibly or not eligible
Before we start
What type of property is it?
Questions
Loft insulation: your questions answered
How much does loft insulation cost?
Typical installed prices in London and the South East, including VAT and before any grant: £500–£1,000 for a mid-terrace; £600–£1,300 for a semi-detached or end-of-terrace house; £900–£1,800 for a detached house; £900–£2,000 for a bungalow; £400–£900 for a flat (top floor). Prices updated 11 October 2026. A survey confirms your final figure.
How thick should loft insulation be?
Current guidance for most homes is 270–300 mm of mineral wool: a first layer between the joists and a second layer laid across them. Anything much thinner is worth topping up.
Can I still use my loft for storage after insulating it?
Yes, but don't board straight over the joists — that squashes the insulation and cuts its performance. Raised loft boarding on loft legs keeps the full depth and gives you a storage deck.
Will loft insulation cause condensation in my roof?
It can if the roof space isn't ventilated, which is why we keep the eaves clear so air can move, insulate and draught-seal the hatch, and lag pipes and tanks left in the cold loft.
Can I get a grant for loft insulation?
You may. Loft insulation is one of the measures ECO4 and Warm Homes: Local Grant can fund for eligible households, depending on income, benefits, your EPC and where you live. Our 60-second checker tells you what's likely.
Group A
More in loft and roof insulation
Loft insulation top-up
An extra cross-layer over existing insulation to reach the recommended 270 mm or more.
Blown loft insulation
Loose-fill insulation blown into awkward, shallow or low-headroom lofts that rolls can't reach.
Loft clearance and replacement
Old, damp or damaged insulation removed, the loft cleaned, then new mineral wool fitted.
Raised loft boarding and storage
Loft legs or raised boarding over full-depth insulation, so storage doesn't crush it.
Insulated loft hatch and ladders
An insulated, draught-sealed hatch and loft ladder — a small add-on that stops a big leak.
Room-in-roof insulation
Insulating the sloping ceilings, stud walls, flat ceiling, gables and dormer cheeks of an attic room.
Begin your project
Price loft insulation in two minutes
See a price range for your property type, with grants and 0% VAT applied where they fit. A survey always confirms the final figure.