Wall ties and cavity insulation
The surveyor notes colder patches on an inside wall and suggests the cavity fill may be patchy. What thermographic survey has that hand test not been?
It has not been a thermographic survey at all. The surveyor felt colder patches on an inside wall and suggested the cavity fill may be patchy. A hand on plaster is not a camera survey, not a map of the insulation, and not an opening of the cavity. The suggestion is a hypothesis from touch and from what fill is said to be there. The home survey has not proved gaps, has not measured heat loss, and has not shown where any missing fill starts and stops.
Last reviewed 24 October 2026. Written for buyers in England and Wales unless this answer says otherwise. No named surveyor has signed this page. It is general guidance, not a report on your house, and not legal advice.
What is the fuller explanation?
Thermography uses a camera to record surface temperature in conditions chosen for that job. Feeling a cold patch on a visit is a different and rougher clue. The cold may be a bridged cavity, missing fill, a damp spot, a north wall or furniture that was standing there. The survey can say the patches felt colder and that patchy fill is possible. It cannot draw the insulation from the palm of a hand. Suggesting a cause is not the same as a thermographic survey that was never commissioned.
If you need the pattern of the fill, ask for a thermographic survey or for the installer's own record, as a separate step. Tell the solicitor the home survey has only noted cold patches and a suggestion. Do not describe a hand test as camera evidence when you speak to a lender or an insurer. The cavity was not opened, and the fill was not mapped.
What should you ask your surveyor?
- Which patches felt colder, and on which wall?
- Did you carry out a thermographic survey, or only a hand check?
- Is patchy fill recorded as a suggestion rather than as a mapped result?
What are the typical next steps?
- Treat the cold patches as a hand note, not a thermographic survey.
- Do not describe the suggestion of patchy fill as a map of the cavity.
- Commission a proper heat survey only if you need the fill pattern.
Costs vary with the building and with who you instruct. Where this page does not cite a published figure, ask the surveyor, a relevant specialist, or your solicitor for a written quote. Do not treat a forum average as the price.
Also asked about this
If the room was unheated, do the cold patches still show missing fill?
Not by themselves. An unheated room can feel uneven for several reasons. The survey suggested the cavity fill may be patchy after a hand check. That check was not a thermographic survey and did not open the wall. The suggestion stays a suggestion. Heating, or the lack of it, was not a controlled test of the insulation.
Does a cavity-fill guarantee prove there are no gaps?
No. A guarantee is paper. The survey did not read it as a map, and the hand test was not a thermographic survey of the fill. Cold patches prompted a suggestion of patchiness, not a proof. If a guarantee exists, it still does not convert touch into a camera survey. The gaps, if any, were not plotted.