How much does loft insulation cost?
Insulating a typical loft from bare joists to 270 mm costs about £750 when done professionally, according to the Energy Saving Trust, and topping up from 120 mm costs about £600. In Northern Ireland the Trust's figures are higher, at about £1,100 and £700.
Our guide prices for an average-sized loft are below. They include VAT where it applies; installing insulation in a home is zero-rated until 31 March 2027.
| Home | Typical loft floor | From bare joists | Top-up from about 100 mm |
|---|---|---|---|
| Top-floor flat | about 40 m² | £495 to £845 | £395 to £595 |
| Terraced house | about 35 m² | £495 to £745 | £395 to £545 |
| Semi-detached or end-terrace | about 45 m² | £545 to £945 | £395 to £645 |
| Detached house | about 60 m² | £745 to £1,245 | £495 to £845 |
| Bungalow | about 70 m² | £895 to £1,445 | £595 to £995 |
What changes the price?
- Loft floor area, which grows with the footprint of the house, not the number of bedrooms
- How much insulation is there now, and whether it can stay
- Access: a small hatch, a low pitch or a loft full of belongings adds time
- Extras such as raised boarding, a new insulated hatch, a ladder or ventilation
- The material: sheep's wool or wood fibre costs two to three times as much as mineral wool
Why do bungalows cost more than houses?
A bungalow's loft covers the whole footprint of the home, so the loft floor is larger than a two-storey house with the same number of bedrooms. More floor means more insulation, even though the job is often easier to reach.
Is the cheapest quote the best value?
Not always. Check that the quote states the finished depth, that the eaves will be kept clear, that the tank and pipes will be lagged (we include this in every insulation price) and that downlights will be dealt with. A cheaper price that leaves those out can cost more later.
Related services
Sources: Energy Saving Trust: roof and loft insulation; Which?: loft insulation costs and savings; LABC: building regulation requirements for loft insulation; GOV.UK: extending the ECO4 end date, government response; GOV.UK: VAT on energy-saving materials (notice 708/6); Property Care Association: spray foam guidance.