We’ve gone sale-agreed on a home with a moisture issue. Should we walk away?

We have just gone sale-agreed on a small apartment. We showed a friend who has some construction experience the apartment, and they said there were signs of moisture throughout it. This was scary as we’ve never made it to the sale-agreed stage before, and now we don’t know what to do. Would you recommend we go ahead with the purchase and fix any issues as they arise or would it be better to walk away?
Congratulations on reaching the sale-agreed stage. In today’s competitive market, this is a real achievement.
Hearing about a moisture issue is disappointing, and your concerns are valid. Buying a property is a big decision and moisture issues are understandably unsettling. Let’s review some considerations to help you make an informed choice.
First, identifying the exact source of the moisture is crucial, as different causes entail different types of remedial action. There could be several issues at play here.
It’s important that you rule out all three at the outset. If they are ruled out, based on your description I’d suggest this may be a surface condensation issue. Condensation occurs when warm, humid air meets cooler surfaces such as windows and walls, forming moisture. This issue is common in properties with limited ventilation or poor insulation and can lead to mould growth if not addressed.
Condensation often arises from high relative humidity indoors, combined with inadequate ventilation or insulation. When indoor humidity levels are more than 70 per cent, condensation is more likely to occur as the air has a high moisture content, which tends to settle on cooler surfaces.
You should consider purchasing a relative humidity monitor and ask for it to be placed in the apartment. These devices are affordable and help you track if high humidity is a key contributor to the moisture problem. If readings consistently show above 70 per cent, condensation is likely, and steps should be taken to manage it.
The lifestyle habits of the previous occupants can also affect condensation levels. Drying clothes indoors, infrequent use of extractor fans in kitchens and bathrooms, and inconsistent heating can all elevate humidity. Poorly managed ventilation, coupled with temperature fluctuations, creates the ideal conditions for condensation.
If condensation is indeed the issue, some adjustments can often help reduce it:
Condensation and mould issues are typically manageable when relative humidity is kept below 70 per cent and thermal bridges are minimised. Making these adjustments can often be both effective and cost-efficient.
If there is any possibility that the moisture is due to a more serious issue, such as damp penetration or an undetected leak, I suggest you engage the services of a chartered surveyor to investigate the issue. This would ensure that you understand the source and its implications before you proceed.
If the issue is condensation, targeted improvements in ventilation, heating, and insulation should help you manage it, especially if you monitor and keep humidity below 70 per cent.
But clarity is key and you need to have that — and peace of mind — before you proceed.
Damian King is a chartered building surveyor and a member of the Society of Chartered Surveyors Ireland
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