Condensation and Mould Linked to Occupier Behaviour – A Proportionate Response under Awaab’s Law
The Problem
Concerns were raised by the occupiers regarding condensation and mould formation, primarily within the bathroom and the main bedroom, most notably around the bedroom window area.
Given the current legislative environment including the introduction of Awaab’s Law and the forthcoming Renters’ Rights Act it was essential that the issue was approached in a way that was reasonable, evidence-led and proportionate, even where occupier behaviour appeared to be a contributing factor.
Our Assessment
A review of the property configuration and occupier feedback identified the following key points:
The occupiers were reluctant to open windows for ventilation, citing heat loss and discomfort
This behaviour appeared to be influenced by experience of newer properties with built-in background ventilation (e.g. trickle vents)
The existing window profiles were too slim to allow for retrospective installation of trickle vents
Permanent background ventilation options (air bricks or wall vents) were technically possible, but would introduce cold external air and were likely to be resisted by the occupiers
The bedroom radiator was undersized and a single panel unit, limiting heat output around the coldest part of the room (the window area)
No evidence of penetrating damp or building defects was identified in the affected areas.
Diagnosis
The mould was diagnosed as condensation related, driven primarily by insufficient ventilation combined with low surface temperatures around the window area.
While occupier behaviour (limited window opening) was a significant factor, legislation requires landlords to demonstrate that reasonable mitigation measures have been considered and implemented where practicable.
Remedial Strategy
Rather than pursuing invasive or contentious measures, a proportionate and occupier-acceptable solution was recommended.
The approach focused on increasing localised heat output to raise surface temperatures above the dew point, reducing the likelihood of condensation forming without introducing unwanted cold draughts or permanent external ventilation.
This strategy was considered reasonable in the context of Awaab’s Law, as it demonstrated active steps to mitigate the issue while acknowledging behavioural influences.
Works Undertaken
The agreed scope of works included:
Replacement of the existing single panel bedroom radiator with a wider, higher-output double panel convector radiator
Adjustment of pipework and installation of new thermostatic controls
Full drain-down, refill, balancing and commissioning of the heating system
Localised mould treatment around the affected bedroom window
Stain blocking and repainting in colour-matched finishes
Resealing around window frames following treatment
All works were completed as a single, coordinated intervention.
Outcome
The increased heat output improved surface temperatures in the coldest part of the room, reducing condensation risk at the window. Mould-affected areas were properly treated and redecorated, restoring the internal finish.
While it was clearly communicated that no intervention can fully resolve condensation where ventilation habits do not change, the measures taken demonstrated a reasonable, proportionate and evidence-based response, aligned with current legislative expectations.
Key Takeaway
This case highlights the importance of balancing building performance with occupier behaviour, particularly under Awaab’s Law.
Condensation-related mould cannot always be eliminated through building works alone, but landlords must be able to show that practical mitigation steps have been explored and implemented. In this instance, targeted heating upgrades and localised treatment provided a defensible and proportionate solution.