Moisture problems in a housing company: signs, reporting, liability
In this article
A moisture problem rarely starts with a major water damage incident. More often the first sign is small: the bathroom is slow to dry, there is darkening next to a window, the basement smells more than usual, or paint keeps flaking off in the same spot. Even small signs should be taken seriously. When a suspicion arises, it helps to know what to do and how responsibility for investigating and repairing is divided.
Moisture does not always show where the fault is
Some moisture damage is noticed immediately, when a pipe bursts or water drips from the ceiling. But moisture can also get into the structures gradually: rainwater is directed to the wrong place, the ventilation does not remove moisture, or there is damage to the waterproofing in a wet room that the resident cannot see. Wetting inside a structure can stay hidden for months. Autumn rains and temperature fluctuations often bring a hidden problem to light.
Water also travels within structures. A visible mark may be the result of a fault elsewhere, and a roof leak, for example, often shows up somewhere other than where the water got in.
Moisture and mould are not the same thing. Moisture can be temporary condensation, caused by everyday use, or a sign of water getting into the structure. Possible microbial damage requires a proper investigation, and no conclusions should be drawn from a smell, a stain or a single measurement alone.
Signs not to ignore
Observations should be taken seriously, especially when they are new, recurring or getting worse. A single crack in the paintwork does not tell you much, but if the same spot darkens, the paint comes off and the surface feels damp, the cause is worth investigating.
Smell
A new or stronger smell, or one linked to a particular space or time of year, is a good reason to look into the situation. A smell tells you that something is worth investigating, but not what it is.
Darkening, peeling paint and swelling
Darkening on a wall or ceiling may be due to dirt, the surface material, condensation or moisture in the structure. Keep a particular eye on darkening that spreads or appears near pipes, windows, wet rooms or the roof. If paint keeps peeling off the same spot, repainting will not help, because the source of the moisture remains. Skirting boards, door frames and wooden floors can also swell. If a door starts behaving differently for no obvious reason, look at the surrounding structure too.
Wet rooms
The bathroom is the apartment’s most important moisture risk, because normal use generates a lot of moisture there and even a small fault puts strain on the structures every day. Watch whether the floor dries normally, whether the floor drain drains properly and whether there are changes in the joints, tiles or surfaces. A clogged or leaking floor drain is a common source of water damage, so report it straight away.
If moisture damage is uncovered during a shareholder’s own bathroom renovation, do not carry on working on structures that are the company’s responsibility on your own. Notify the company and let it investigate the damage. A bathroom renovation must in any case be notified to the company before work begins.
Windows and ventilation
Condensation explains some of the moisture on windows, but recurring moisture, darkening or peeling paint around the window reveals may point to a structural leak. Stuffy air, windows misting up on the inside and cooking smells that linger for a long time are typical signs of poor ventilation. Even so, do not close the vents or change the settings yourself. More in the articles on housing company windows and housing company ventilation.
Rainwater, basement and attic
Heavy rain reveals whether water is directed away from the building in a controlled way. If water pools along the wall or runs towards the foundations, check the gutters, downpipes, roof drains and the slope of the ground. After rain, also check for new damp marks or salt crystals on the facade or the basement walls. In the attic, look at the underside of the roof and at penetrations. More on rainwater in the article on housing company gutters.
When a suspicion arises
The first step is gathering information. Record where and when the observation was made, whether the phenomenon is new or has continued for a long time and whether anything similar has been seen elsewhere. A photo, a date and a short description are enough: “a brown mark appeared on the ceiling on 14 September” or “the darkening next to the window has grown over the summer”. The records build a timeline that helps later in finding the cause. Earlier leaks, renovations and burst pipes are also useful background information.
Notifying the company
Under chapter 4, section 8 of the Limited Liability Housing Companies Act (asunto-osakeyhtiölaki, 1599/2009), a shareholder must notify the company without delay of a fault or defect that the company is responsible for repairing. From 1 October 2026, the same applies to company spaces and areas the shareholder uses where the right of possession is not based on the articles of association or a lease, such as a storage space made available to the shareholder or the yard area in front of the apartment. The notification is made to the property manager or the maintenance company as the company instructs, and in a way that leaves a record.
The person reporting does not need to know the cause. “There is moisture damage here” often goes too far. “There is a new dark patch on the wall that has grown over the past month” is better, because it describes the observation precisely. Guidance on making a good report is in the article on fault reporting in a housing company.
Avoid cosmetic repairs
Painting over a damp mark or renewing skirting boards and silicone seals can make the surface look better for a while, but it does not tell you whether the source of the moisture has gone. A cosmetic repair can even make a later investigation more difficult. A new damp mark should not be painted over before the cause has been established.
Measurements and condition surveys
A surface moisture meter gives indicative information on differences in moisture, but the reading alone does not tell you the actual moisture content of the structure. The result is affected by the layers of the structure, the materials, and wires and pipes running inside the wall. A single abnormal reading does not prove damage, and a normal reading does not rule it out.
If observations recur, get worse, appear in several rooms or their cause cannot be assessed visually, you need a building expert and a condition survey suited to the situation. Its purpose is to find the source of the moisture, the extent of the damage and the repairs needed. The survey is scaled to the observation: not every dark patch requires an extensive survey, and structures are not opened up just to be on the safe side.
Who is responsible?
Under chapter 4, section 2 of the Limited Liability Housing Companies Act, the company is responsible for the structures, insulation, windows, and heating, water, drainage, ventilation and other core systems. The shareholder is responsible for the interior of the apartment, such as surface materials and fixtures (chapter 4, section 3). If the interior is damaged because of a fault in a structure that is the company’s responsibility, or because of its repair, the company also repairs the interior. The articles of association can provide otherwise, so check your own articles of association and division of responsibilities table.
With moisture damage, responsibility can only be settled once it is known where the fault is and what has caused it. The first question is therefore the cause and extent of the damage, not who pays. Investigating damage to a structure that is the company’s responsibility is the company’s job.
Maintenance responsibility and liability for damages are different things. Even if the repair is the company’s responsibility, the company does not automatically pay for, say, temporary accommodation or damaged personal belongings. These are governed by the chapter of the Act on damages, and home insurance is often relevant too.
When to act immediately
An active leak, rapidly spreading moisture or a large amount of water is dealt with immediately: turn off the water, call the maintenance on-call service and prevent further damage. If water gets into electrical equipment or electrical rooms, do not touch them. An observation that keeps getting worse is also a reason to act quickly: if a damp mark on a wall grows after every rain, do not put the matter off until the next round of annual repairs. Instructions for sudden damage are in the article on water damage in a housing company.
Questions for the board
- Has the building had moisture or water damage, and can the repair documents be found?
- Have residents reported smells, darkening or wet rooms that are slow to dry?
- Are the gutters, downpipes and rainwater drainage working?
- Is the ventilation working as designed?
- Are the building’s high-risk points known, and has their monitoring been agreed?
The fact that there has been no water damage does not mean there is no moisture problem. Water damage is an event; a moisture problem can be a slowly progressing process. The board does not need to diagnose damage itself, but it should make sure observations are recorded and handled systematically, so that the next review does not start from scratch.
Frequently asked questions
Can moisture damage be hidden?
Yes. Moisture can be in a floor or wall structure without showing on the surface. If several observations point in the same direction, the absence of visible damage does not settle the matter.
Who pays for a moisture investigation?
It depends on what is causing the problem and whose responsibility the building component is under the law and the articles of association. Investigating a structure that is the company’s responsibility is the company’s job.
Is a damp mark always a sign of serious damage?
No. What matters is finding out where the moisture is coming from, whether the phenomenon is ongoing and whether the structures are damaged.
Sources: Limited Liability Housing Companies Act 1599/2009, Finlex (in Finnish) (opens in a new tab); EV 65/2026 vp (in Finnish) (opens in a new tab).
This article provides general information and does not replace case-specific legal or technical advice.
