Building insurance for an unoccupied house is bought to protect a fabric that starts working against itself the moment the heating goes off. Buildings are designed to be lived in: heated, ventilated, with somebody noticing a drip. Remove the occupants and a predictable sequence begins, and insurers price the sequence rather than the building.
What deteriorates, and in what order
Damp first, because the heating is off and nobody opens a window. Then frost damage to pipes and to any water sitting in a system. Then roof problems that nobody reports, letting water into a void for weeks. Then rot where the damp has persisted, and finally the structural problems that follow: a drain leaking undetected under a corner of a house is one of the commonest causes of subsidence.
Which of that is insured
Escape of water and storm damage are perils, where the policy includes them. Gradual damp, rot, wear and deterioration are not: insurance covers sudden and accidental events, not the slow consequences of leaving a building empty. That distinction is why the maintenance conditions exist, and why an insurer will look hard at how long a problem was developing.
The conditions, read as maintenance rather than paperwork
Heating on or system drained. Inspections at intervals. Gutters clear. Post removed. Each of these is aimed at one of the deterioration paths above. They are not arbitrary: they are the minimum set of actions that keeps an empty building from becoming an uninsurable one, which is why insurers make them conditions rather than recommendations.
Ventilation, which nobody puts in the policy
No wording requires it and every surveyor recommends it. A house that is heated and never ventilated grows mould; one that is ventilated and unheated freezes. A low continuous heat with trickle vents open is the combination that keeps a building sound over a winter, and it costs less than the first damp claim.
Questions people ask about building insurance for unoccupied house
Is damp in an empty house covered?
Generally not. Insurance covers sudden and accidental events, and gradual damp, rot and deterioration are consequences of the building being left, which is what the conditions exist to prevent.
What is the commonest empty house claim?
Escape of water, usually after a frost, running undetected until somebody visits.
Do I need to ventilate as well as heat?
No wording requires it and it is what keeps a building sound. Low continuous heat with trickle vents open is the usual advice.
Can an empty house become uninsurable?
In practice yes, if it deteriorates far enough. Insurers decline buildings that are visibly derelict or have been unattended for long periods.