Extensions, conservatories and garages with ECO4 insulation and heating: a UK household checklist (2026)

Guide by ApplyFreeBoiler.uk (Reliant Energy Solutions Ltd), a heating and insulation installer in Bury, Greater Manchester. We are not the government, Ofgem or an energy supplier.

Lots of UK homes have been extended over the years, with a kitchen extension, a conservatory, a garage conversion or a bedroom over the garage. These parts of the house are often built differently from the original home, so they can need different treatment when insulation or heating work is planned under ECO4. This checklist is general information from ApplyFreeBoiler.uk, a heating and insulation installer in Bury. It does not replace the surveyor's assessment or building control advice, and it does not guarantee funding.

1. Point out every extension at the survey

Show the surveyor any extension, conservatory, porch, garage conversion or room over a garage, and tell them roughly when it was built if you know. Newer and older parts of the same home can have different walls, roofs and floors.

2. Different walls may need different insulation

An extension may have a different wall type from the main house, for example a newer cavity wall next to an older solid wall. Ask the installer which walls are included in the plan and which are not.

3. Flat roofs and loft spaces

Extensions often have flat roofs or small roof voids with no loft hatch. Ask whether the extension roof is part of the insulation plan and how it would be reached, rather than assuming the main loft work covers it.

4. Rooms above an integral garage

A bedroom over a garage can feel cold because the floor sits above an unheated space. Mention this to the surveyor and ask whether anything can be done about that floor as part of the work.

5. Conservatories and heat loss

Conservatories lose heat quickly. Keep the door between the conservatory and the house closed in cold weather, and ask the installer whether a radiator in the conservatory should be on the new heating system or not.

6. Radiators in extensions

If an extension was added after the old heating was fitted, its radiator may be on a long pipe run or may be undersized. When the boiler is replaced, ask the installer to check that every room, including the extension, heats properly.

7. Keep paperwork for extensions

If you have building control sign-off or planning papers for an extension, keep them handy. They can help answer questions about how and when that part of the home was built.

8. Check funding and local figures

See ECO measures by council on ApplyFreeBoiler.uk, built from DESNZ Household Energy Efficiency statistics, to see how many ECO measures have been installed in your local authority area. Use the ApplyFreeBoiler.uk eligibility check to see whether an ECO4 heating or insulation pathway may be available for your home in England, Scotland or Wales. ECO4 is due to close on 31 December 2026.