Home › Upgrades › Roof and Room-in-Roof Insulation
Roof and Room-in-Roof Insulation: cost, savings and EPC impact
Not every roof has a simple loft that you can lay a quilt across. Where there is a room in the roof, sloping ceilings, dormers or a flat roof, the insulation has to go in a different way.
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
For a room in the roof, insulation goes between and over the rafters and into the knee walls and slopes. For a flat roof it is usually added above or below the deck.
These jobs are more involved than a loft top-up. A good installer will look at ventilation and moisture carefully, because roofs that are insulated badly can trap damp.
Indicative cost, savings and EPC effect
| Typical cost | £1,500 to £6,000 |
|---|---|
| EPC points (SAP) | +3 to +10 |
| Bill saving | £50 to £250 a year |
Needs a survey. Cost varies a lot with roof type and access.
Prices vary a lot by home. See the Energy Saving Trust’s retrofit guide for general background.
Gains can be noticeable in homes where the roof is a big heat-loss area, but because the work is so varied the range is wide. See how EPC ratings work. Savings from several upgrades do not simply add up.
Is it right for your home?
- Homes with converted lofts or attic bedrooms, where a loft quilt is not possible.
- Flat roofs on extensions and some bungalows or terraced houses.
- A roof in poor repair should be fixed before it is insulated.
What affects the price
- Roof type and complexity
- Access and scaffold
- Whether the roof covering has to come off
- Dormers, roof windows and chimneys
Questions to ask any installer
- Will a survey look at ventilation and condensation risk?
- What U-value or insulation thickness will you achieve, and in which parts of the roof?
- Does the work need building regulations sign-off, and who will arrange it?
Always get a proper survey and written quote. We introduce you to one vetted firm to do that, and explain why only one.
Related upgrades
Ready to see options for your home?
Tell us your postcode and the upgrades you are thinking about. It is free, and you are not committing to anything.
Pick your upgrades and get matched