Condensation Returning as the Weather Gets Colder? A Guide for Landlords
A tenant sends a photo of a wet bedroom windowsill. “I wiped it yesterday,” they say, “and it was wet again this morning.” By the time you visit in the afternoon, the glass is dry. What should you check?
Start with the pattern the tenant has noticed. A little mist on cold glass that clears during the morning is a different observation from a sill that needs drying every day, peeling paint around the frame or mould spreading onto the wall. All three can look much the same in a tightly cropped photograph.
Why does it come back when the weather turns colder?
When moist indoor air meets a surface cold enough, some of that moisture settles as droplets. A bedroom window can be the first place you see it after an occupied night. In colder weather, the wall beside the frame or an outside corner behind a wardrobe can also be cool enough for moisture to collect.
That tells you where moisture is settling. To understand why it keeps returning in this particular room, look at the heating, ventilation and condition of the property together. A tenant who has lived there for years may be able to tell you exactly when the pattern changed.
What to ask when the first photo arrives
Ask which side of the glass is wet, how often it happens and whether the frame or wall stays damp after the glass dries. Does it happen on cold, clear nights as well as after rain? Has the tenant noticed a musty smell, a change in the heating or a fan that used to work better?
A wider photo can show where the patch sits in relation to the window, ceiling or outside wall. Pair it with a close-up and record the date the tenant first reported it. If you visit after the window has dried, include their account alongside what you could see that afternoon. Arrange the visit promptly even if they cannot supply photos.
What to look at during the visit
In the bedroom, check the frame, the wall around the window and any accessible outside corners. Ask whether the room heats up properly. Follow the path moisture takes through the rest of the home too. For example, if the bathroom fan makes a noise but steam lingers long after a shower, it is worth arranging to check how effectively it extracts air.
A brown patch above the window that grows after driving rain calls for a different line of enquiry from droplets on the inside of the glass each morning. Record both if both are present. Where a leak or building defect is suspected, our guide to damp and mould assessments and building surveys explains who can help with the next step.
If humidity readings are available, compare them with the tenant’s account and what you see in the room. Our guide to what environmental sensors can tell a landlord explains how a pattern of readings can help direct an inspection.
When a tenant reports damp or mould in Scotland
If a landlord becomes aware that a rented home may be affected by damp or mould, Scottish guidance requires a competent person to investigate within 10 working days. The landlord must give the tenant a written summary within three working days of the investigation concluding. These are maximum timescales. Record the original report date and respond sooner where the circumstances require it.
Keep the tenant informed about who is visiting, what will be checked and when they can expect an update. A suggestion to open a window is little help if the window is painted shut or the heating has failed. Listen to what the tenant can reasonably do and address the property issues the investigation identifies.
Our guide to Awaab’s Law for Scottish private landlords covers the next steps if repairs are needed. The Scottish Government guidance sets out the full timescales.
When would an assessment help?
If the same patch keeps returning, several rooms are affected or the cause is unclear, a room-by-room assessment can give you a dated record of the visible conditions, ventilation and relevant moisture readings. That record can help you decide whether a repair contractor, surveyor or other specialist needs to investigate further. Agree a follow-up with the tenant so you know whether the issue returns after action is taken.
Thorn carries out damp and mould assessments for landlords and letting agents across Glasgow and East Dunbartonshire. If you are unsure what information would be useful before a visit, Ask Wendy about the property and what the assessment covers.