Sources: Citizens Information — minimum standards for rented homes (Housing (Standards for Rented Houses) Regulations 2019) and SEAI — ventilation. Checked 19 October 2026.
Three different problems
Condensation: mist on windows, spots on cold outside walls and behind wardrobes, worse after showers, cooking or drying clothes indoors. The wall is not necessarily leaking.
A leak: a brown ring on a ceiling under a bathroom, a pipe chase that is wet, or a stain that grows after rain. That is plumbing or the roof, not a cleaning job.
Moisture from the ground: plaster low on the wall that is soft, salty or bubbling, often with a tide line. Painting that is a decorating job done too early.
What you can check yourself
Use the extractor when you cook or shower, and leave it running afterwards. Do not dry clothes in a closed room. Leave a gap behind furniture on outside walls. Look at trickle vents and at the eaves in the attic: insulation must not block the air path. SEAI’s ventilation note is that cooking, laundry and showers put water vapour into warm indoor air, and that vapour can condense on cold surfaces and in a cold attic if the air cannot leave.
Wipe small spots of surface mould with a cloth you throw away. Do not mix bleach with other cleaners. Do not sand mouldy paint — that spreads it. If the spots return in the same cold corner after two weeks of ventilating and heating, the room needs a better extract or the wall is wet for another reason.
When to stop
Stop cleaning and stop buying stain-block paint if any of these are true: the ceiling is damp or sagging; you can smell must in the attic; skirting plaster is soft or salty; a stain tracks a pipe; mould covers more than a cold corner and keeps returning. A painter can make it look finished. The mould comes back if the water is still arriving.
Call a plumber for a wet ceiling under a bathroom or a pipe. Call a roofer if the attic is wet after rain. Call a builder for soft plaster, a failed damp course, or a wall that is wet from outside. Electrical fittings in a wet zone need a Safe Electric contractor — do not keep using a socket that has been damp.
If you rent
Citizens Information summarises the 2019 regulations: for a private rented house or apartment the landlord must keep the property free of damp and structurally sound, and every room must be ventilated, with heating the tenant can control. Tell the landlord in writing first. Local authorities enforce these standards. The same page notes that not every rule applies in the same way to local-authority and approved-housing-body lettings. This catalogue does not handle the dispute.
Who to call
Leaks and heating: plumbing and heating — Dublin, Cork, Galway. The fabric of the house: building and renovation — Dublin, Cork. A town list is submitted for search only when that town has at least 10 businesses in the trade.