Condensation Disputes And Why They Are Hard To Settle

Few tenancy disagreements recur as reliably as mould in a bedroom corner. Both sides have a defensible position, which is precisely why the argument does not resolve.

Two causes, one appearance

Mould grows where a surface stays damp. That happens when water enters the building, and it also happens when internal moisture condenses on a cold surface.

The visible result is similar, so an inspection that stops at the mould has not identified anything. The pattern, location and history are what separate the causes.

Landlords tend to see evidence of drying laundry and closed vents. Tenants tend to see single glazing, no extraction and a wall that is cold to the touch.

Both explanations are usually partly right

A household generates moisture through cooking, washing and breathing, and that output varies with occupancy and habits.

The building determines where that moisture goes: whether it can leave through extraction and ventilation, and whether any internal surfaces are cold enough for it to condense on.

A well-ventilated building tolerates a high moisture load. A sealed one produces condensation even with a modest load, so attributing it wholly to either party misdescribes the mechanism.

Where responsibility usually falls

Landlords are generally responsible for the structure and for the installations that serve it, which includes extraction equipment and the condition of windows and walls.

Tenants are generally expected to use the property in a reasonable manner, which includes using extraction provided and not blocking ventilation.

How these obligations are defined, and what standard of habitability is required, differ by jurisdiction and are changed by legislation, so the local position governs.

Evidence changes the conversation

Photographs with dates, records of when the problem appears and disappears through the year, and written reports to the landlord establish a sequence that memory does not.

Where extraction exists, checking that it works and vents outside rather than into a void is a specific, testable question rather than a matter of opinion.

Surface temperature readings and a record of humidity over time move the discussion from assertion to measurement, which is what an inspector or adjudicator can act on.

Why it surfaces at the end of a tenancy

Mould that was tolerated during occupation becomes a deposit deduction at check-out, presented as damage to decoration caused by the tenant.

A tenant who reported the problem in writing during the tenancy has a different position from one raising it for the first time in response to a deduction.

That difference is the practical reason to report early, even when the tenant expects nothing to be done about it.