Damp and condensation and ECO4: questions UK households ask (guide 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.

Damp, mould and condensation are common in cold UK homes, especially on outside walls, around windows and in bathrooms and bedrooms. Heating and insulation work can affect how warm the walls are and how moisture moves through a home, which raises a few common questions when a home is assessed for ECO4. This guide covers questions households commonly ask. It is general information from ApplyFreeBoiler.uk, a heating and insulation installer in Bury. What is recommended depends on the survey and the scheme rules at the time. This page does not guarantee funding.

1. Show where the damp is

Point out every room with damp patches, black mould or peeling paint, and whether it is worse in winter.

2. Condensation on windows

Say whether windows run with water in the mornings and which rooms are worst.

3. Ventilation

Mention whether the kitchen and bathroom have working extractor fans and whether trickle vents on windows open.

4. Leaks and gutters

Note any roof leaks, blocked gutters or leaking pipes, as these cause damp that insulation will not fix.

5. Previous insulation

Say whether the walls or loft have been insulated before and when damp started.

6. Your current heating

Say what heating you use now, the age of your boiler and how often you can afford to have it on.

7. Clear access

Clear space around the boiler, meters, loft hatch and damp areas before the survey visit.

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.