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Loft Insulation: cost, savings and EPC impact
Loft insulation is usually the first upgrade worth looking at. Warm air rises, and an uninsulated or thinly insulated loft is one of the easiest places for heat to leave a house.
IndicativeFigures on this page are indicative ranges for a typical UK home. They are not a quote, a survey or an EPC. Your home will differ.
What it is
Insulation is laid between and over the joists to a depth of about 270mm, or topped up where there is some already. In an unboarded loft it is a straightforward job that is often finished in a few hours.
If you store things in the loft, the insulation can be raised on a platform so you keep usable space without squashing it, because squashed insulation works less well.
Indicative cost, savings and EPC effect
| Typical cost | £500 to £1,000 |
|---|---|
| EPC points (SAP) | +2 to +10 |
| Bill saving | £20 to £150 a year |
Biggest gain if you have little or none today. Topping up from ~120mm saves much less.
For comparison, the Energy Saving Trust’s average installed cost for a typical semi-detached home is £750 (loft insulation from 0 to 270mm). See Energy Saving Trust: Retrofit explained for the latest figures.
Loft insulation can lift an EPC by a few points, and more in a home where it is currently missing. How much depends on the rest of the house. See how EPC ratings work. Savings from several upgrades do not simply add up.
Is it right for your home?
- Homes with little or no loft insulation get the biggest gain. Topping up from about 120mm to 270mm saves much less than starting from nothing.
- A loft with a damp problem, a leaking roof or old cabling needs those things sorted first.
- If there is a flat roof, a room in the roof or sloping ceilings, see our page on roof and room-in-roof insulation instead.
What affects the price
- Loft size and how easy it is to get into
- Whether old insulation needs removing
- Whether you want boarding or a storage platform
- The material used (mineral wool is common; sheep’s wool and others cost more)
Questions to ask any installer
- How deep will the insulation be when finished, and what is it made of?
- How will the loft hatch be insulated and draught-proofed, and will ventilation at the eaves stay clear?
- What happens to water tanks and pipes? They should end up on the warm side or be insulated themselves.
Always get a proper survey and written quote. We introduce you to one vetted firm to do that, and explain why only one.
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