The average cost of insulating a floor between flats is £550–£1,200 per flat, but grants rarely cover this work
Insulating the floor between flats can reduce heat loss and lower energy bills, but the rules for grant funding are strict. The typical cost range for insulating a suspended timber floor between flats is sourced from the Energy Saving Trust’s 2026 insulation cost guide (Energy Saving Trust, 2026).
Only floors above unheated spaces like basements or garages may qualify. Expect to pay out of pocket for most upper-floor flats.
- Cost £550–£1,200 per flat for suspended timber floors
- GBIS and ECO4 exclude party floors between flats
- Ground-floor flats above unheated voids may qualify for grants
- Typical annual saving is £40–£80 for gas-heated flats
- Expect to pay out of pocket unless floor is above basement or garage
- The average cost of insulating a floor between flats is £550–£1,200 per flat, but grants rarely cover this work
- Quick numbers grant eligibility, costs, and savings for flat floor insulation
- The GBIS and ECO4 both treat floors between flats as "party floors", and that means no grant
- You can confirm eligibility by checking your floor's U-value and whether it sits above an unheated space
- The only flat floor insulation that qualifies for a grant is a ground-floor flat above an unheated space
- How to verify your installer is certified for floor insulation grants (MCS and TrustMark required)
- The direct answer flat floor insulation is not grant-eligible for most flats, only ground-floor flats above unheated spaces qualify
Ground-floor flats are more likely to be eligible for grants than upper-floor flats because heat loss is measured against the ground, not the flat below. The Great British Insulation Scheme (GBIS) and ECO4 both exclude “party floors” (floors between separate dwellings) from their core measures list (GOV.UK, 2026). Homeowners should expect to pay out of pocket unless the floor sits directly above an unheated space such as a basement, garage, or external void.
Quick numbers grant eligibility, costs, and savings for flat floor insulation
| Floor type | Average cost (per flat) | Grant eligibility (GBIS/ECO4) |
|---|---|---|
| Suspended timber floor above unheated basement | £600–£1,200 | Eligible if U-value ≥0.70 W/m²K |
| Suspended timber floor above another flat | £550–£1,000 | Not eligible, party floor |
| Solid concrete floor above unheated void | £700–£1,500 | Eligible if U-value ≥0.70 W/m²K |
| Solid concrete floor above another flat | £650–£1,300 | Not eligible, party floor |
| Typical annual saving (gas-heated flat) | £40–£80 | Not applicable |
Source: Energy Saving Trust, 2026; Ofgem ECO4 eligible measures list, 2026; DESNZ, 2026.
The GBIS and ECO4 both treat floors between flats as “party floors”, and that means no grant
The Great British Insulation Scheme closed on 31 March 2026. It funded insulation measures only and never covered windows or glazing. ECO4 allows floor insulation only for “ground floors”, defined as floors with a thermal element in contact with the ground or an unheated space (Ofgem ECO4 Guidance Document 2026, section 3.2.4).
A floor between two flats is classified as a party floor, not a ground floor, regardless of which storey the flat is on. The only exception is a ground-floor flat with a floor above an unheated basement or garage, this is treated as a ground floor.
You can confirm eligibility by checking your floor’s U-value and whether it sits above an unheated space
Use the MCS Insulation Installer Standard MIS 3005 to determine your floor’s existing U-value, above 0.70 W/m²K makes it eligible for grant-funded insulation (MCS MIS 3005, 2026 revision). If your flat is on the ground floor and you have access to a basement or underfloor void, measure the distance between your floorboards and the ground, at least 300mm is required for safe installation.
Upper-floor flats cannot meet the “unheated space” condition, so no grant is available regardless of U-value. Contact your local authority’s energy efficiency officer or check the Energy Company Obligation (ECO) postcode checker on GOV.UK (GOV.UK, 2026).
The only flat floor insulation that qualifies for a grant is a ground-floor flat above an unheated space
The Great British Insulation Scheme closed on 31 March 2026. It funded insulation measures only and never covered windows or glazing. The insulation must be installed by an MCS-certified installer and the property must meet the minimum energy efficiency rating (EPC band D or below for GBIS; E, F, or G for ECO4) (GOV.UK, 2026).
Solid concrete floors above unheated voids also qualify, but the installation method is different (rigid board insulation rather than mineral wool). The Great British Insulation Scheme closed on 31 March 2026. It funded insulation measures only and never covered windows or glazing.
How to verify your installer is certified for floor insulation grants (MCS and TrustMark required)
All grant-funded floor insulation must be installed by an MCS-certified contractor, search the MCS Installer Database at mcscertified.com for “Floor Insulation” category (MCS, 2026). The installer must also be registered with TrustMark, the government-endorsed quality scheme for home improvements (TrustMark, 2026).
For gas-safe installations (e.g., if pipework is moved), the installer must hold Gas Safe Register accreditation, this is rare for floor insulation alone. Always ask for a copy of the MCS certificate and a TrustMark logo on the quote before any work begins.
The direct answer flat floor insulation is not grant-eligible for most flats, only ground-floor flats above unheated spaces qualify
If you live in an upper-floor flat, you cannot receive a grant for insulating the floor between your flat and the one below, it is classified as a party floor. If you live in a ground-floor flat with a floor above another flat (e.g., a maisonette above a basement flat), the same exclusion applies.
The only grant-eligible scenario is a ground-floor flat with a floor directly above an unheated basement, garage, or external void, and a current U-value above 0.70 W/m²K. For all other flats, the homeowner must pay privately, typical costs are £550–£1,200 depending on floor area and access (Ofgem ECO4 Guidance, 2026; GOV.UK, 2026).
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Frequently Asked Questions
No, in most cases. The Great British Insulation Scheme and ECO4 both exclude party floors between separate dwellings, according to GOV.UK (2026). Grants are only available if the floor sits above an unheated space like a basement or garage.
The average cost is £550–£1,200 per flat, depending on floor type. Suspended timber floors above another flat cost £550–£1,000, while solid concrete floors above an unheated void cost £700–£1,500, per the Energy Saving Trust (2026).
A party floor is a floor that separates two separate dwellings, such as between flats. Ofgem and GOV.UK define it as a thermal element that does not contact the ground or an unheated space. That makes it ineligible for most grant schemes.
Typical annual savings for a gas-heated flat are £40–£80, based on Energy Saving Trust data (2026). Savings depend on floor type, existing insulation, and heating system efficiency.
Yes, but only if you pay out of pocket. Upper-floor flats are rarely eligible for grants, but insulating a suspended timber floor can reduce heat loss and lower bills by £40–£80 per year, according to the Energy Saving Trust (2026).
