The first question most homeowners ask when they apply for a government grant is what happens next. You have submitted the application, and now someone needs to visit your home. That visit is called a grant home survey, and it is a mandatory step before any installation work can begin.
The average grant home survey takes 60–90 minutes and is required before any work starts under the Great British Insulation Scheme (GBIS), the Boiler Upgrade Scheme (BUS), or the Home Upgrade Grant (HUG) (GOV.UK, 2026). The survey is conducted by a qualified surveyor employed by the installer or scheme administrator, not by the grant body itself, and it is free to you as the homeowner.
The average grant home survey takes 60–90 minutes and is required before any work begins
The survey is a mandatory step for all major government schemes including the Great British Insulation Scheme (GBIS), the Boiler Upgrade Scheme (BUS), and the Home Upgrade Grant (HUG). It is conducted by a qualified surveyor employed by the installer or scheme administrator, not by the homeowner or the grant body itself. The survey is free to the homeowner and is funded as part of the overall grant package (Ofgem, 2026).
The surveyor will contact you to arrange a convenient time. They will need access to every room in your home, including the loft, and will typically spend between one hour and 90 minutes on site. If you are not home for the appointment, the survey cannot proceed and your grant application may be delayed or cancelled.
The surveyor measures your home’s energy performance using the Standard Assessment Procedure (SAP)
The surveyor collects data on property age, construction type, wall and roof insulation, glazing, heating system, and floor area. This data is fed into SAP software to calculate your property’s current Energy Performance Certificate (EPC) rating and the potential rating after grant-funded measures (BRE, 2026).
The survey confirms whether your home meets the minimum EPC threshold for the specific grant. For GBIS, you need an EPC rating of D, E, F, or G. For HUG, you need an EPC rating of E, F, or G and must be off the gas grid (DESNZ, 2026). For BUS, your property must have a valid EPC with no outstanding recommendations for loft or cavity wall insulation.
What the surveyor inspects in each room, a room-by-room checklist
The surveyor follows a standard checklist. In the loft, they measure insulation depth, check access and ventilation, and look for any signs of damp or mould. For walls, they identify cavity wall type, measure wall thickness, inspect external wall condition, and check for existing insulation (Ofgem, 2026).
For windows and doors, the surveyor records frame material, glazing type, and draught-proofing condition. The heating system is inspected for boiler make and model, age, thermostat type, radiator sizes, and pipework insulation. For the ground floor, they establish whether the construction is suspended timber or solid concrete, and check for any existing floor insulation.
Quick numbers, key survey metrics in a single table
| Metric | Typical Value | Source |
|---|---|---|
| Survey duration | 60–90 minutes | TrustMark installer code of practice |
| EPC improvement needed for grant | At least 1 band (e.g., E to D) | DESNZ GBIS guidance |
| Maximum loft insulation depth measured | 270 mm (current standard) | Building Regulations Part L |
| Cavity wall thickness measured | 50 mm or 100 mm | BRE cavity wall guide |
| Boiler efficiency recorded as | SAP seasonal efficiency (e.g., 78%) | Ofgem BUS technical annex |
The surveyor checks eligibility criteria that determine which grant measures you qualify for
For GBIS, the survey confirms your property is in EPC bands D, E, F, or G and has a low-income or vulnerable household occupant (Ofgem, 2026). For BUS, the survey checks that your existing heating system is a fossil-fuel boiler and that the property has a valid EPC with no outstanding recommendations for loft or cavity wall insulation.
For HUG, the survey verifies that the property is off the gas grid, has an EPC below band D, and is in a qualifying low-income area (DESNZ, 2026). The surveyor will also check for any pre-existing damp, condensation, or structural issues that could prevent installation. If these issues are found, the grant may be paused until they are resolved.
The surveyor identifies your home’s specific insulation and heating upgrade opportunities
Based on the measurements, the surveyor recommends the most cost-effective measure(s) for your property. These could include loft insulation, cavity wall insulation, external wall insulation, or a heat pump. The surveyor calculates the estimated annual energy savings in kWh and £ for each recommended measure (Energy Saving Trust, 2026).
For heat pumps under BUS, the surveyor assesses whether the property is suitable for a heat pump. This includes checking radiator sizing, pipework, and outdoor unit location. They will also check that the property has sufficient space for an outdoor unit and that the existing pipework can handle the lower flow temperatures of a heat pump system (MCS, 2026).
The survey produces a written report that you must sign before installation begins
The report includes the survey findings, recommended measures, estimated costs (grant-funded and any homeowner contribution), and expected energy savings. You are given a minimum of 14 days to review the report and ask questions before signing (Ofgem consumer protection rules, 2026).
The signed report acts as your consent for the installer to proceed with the grant-funded work. Keep a copy of the signed report for your records. If you change your mind during the 14-day review period, you can cancel without penalty.
Only MCS-certified installers can carry out the survey for heat pump and solar grants
For the Boiler Upgrade Scheme, the survey must be conducted by an installer registered with the Microgeneration Certification Scheme (MCS) (MCS register, 2026). For insulation grants (GBIS, HUG), the installer must be TrustMark registered and, for cavity wall insulation, have a CIGA (Cavity Insulation Guarantee Agency) certificate (TrustMark, 2026).
You can verify an installer’s MCS certificate on the MCS register website or check TrustMark registration on the TrustMark website. How to check if an installer is properly accredited for government grants Never allow a survey to be conducted by someone who cannot provide proof of registration with MCS or TrustMark. If an installer refuses to show their credentials, contact the scheme administrator before proceeding.
