These are the four legal deadlines set out in The Hazards in Social Housing (Prescribed Requirements) (England) Regulations 2025, as explained in the government's guidance for social landlords. Every clock starts the moment the landlord "becomes aware" of a possible hazard - that is, the moment anyone working for them finds out, however the news arrives.
Predicted visible mould in ~18 days without intervention.
As soon as the landlord finds out about an emergency hazard - a danger so serious that any sensible landlord would act straight away - they have 24 hours to investigate it and, if repairs are needed to make the home safe, to carry them out.
Damp and mould hazards that aren't emergency-level still require investigation - within 10 working days of becoming aware. The landlord must determine whether the home contains a significant hazard and whether relevant safety work is required.
Once the investigation finishes, the landlord has 3 working days to send the resident a written summary. This applies in almost all cases. The summary covers what was found, whether there is a significant or emergency hazard, and what happens next.
Where the investigation identifies relevant safety work, the landlord has 5 working days from the conclusion of the investigation to complete it. If this isn't possible, the landlord must secure suitable alternative accommodation at their expense until the work is done.
If the landlord cannot finish the needed repairs in time (the law calls this window the "initial remediation period" - the 5 working days above), they must pay for suitable alternative accommodation themselves until the work is done.