Hidden defects in a housing company: signs, checks and responsibility
In this article
A housing company repairs the defects it knows about. A burst pipe, a leaking roof or a lift that keeps sticking soon come to light. Slowly spreading moisture, a dripping joint or a window seal that failed years ago, on the other hand, can go unnoticed for a long time because nobody reports them. Hidden defects therefore have to be looked for deliberately, and even small signs are worth taking seriously.
In this article, a hidden defect means a problem that has not yet been noticed or whose significance has not been recognised. It is not the legal concept of a hidden defect in a property sale, and a hidden defect does not automatically mean serious damage.
Small signs
The cause of a hidden defect is out of sight, but it often shows up as small changes:
- recurring moisture marks or discolouration, blistering paint
- recurring condensation
- a dripping joint or valve, rust marks around a pipe
- a damaged seal or joint in a wet room
- a recurring drain smell
- an unusual noise from a pump or other equipment
- a new or growing crack.
None of these on its own proves a serious defect. An observation is not a diagnosis, but it may be a reason for further investigation. An observation is worth taking seriously when it is new, recurs, gets worse, appears in several places or is related to moisture or safety.
Where to look for hidden defects
Roof and loft. The condition of the roof covering, penetrations and joints deteriorates gradually, and the first water mark on a ceiling may mean that a leak has already been going on for a long time. Monitoring the roof must not depend on whether someone on the top floor reports a problem. People rarely go into the loft, so signs of moisture, a mouldy smell and poor ventilation are easily missed. See the loft checklist.
Rainwater, plinth and basement. Blocked gutters and water discharging in the wrong place soak the plinth and foundations, even when nothing shows indoors. In the basement, a new smell, moisture or salt marks and water collecting tell you how the building is handling moisture. If you know what the basement is normally like, you will notice changes.
Facade and balconies. A single crack is not yet a problem, but a growing crack, new cracks or a flaking surface are. A photo of the same spot every year helps to tell normal ageing from progressive damage. On balconies, keep an eye on drainage, rust marks and spalling.
Windows and doors. A seal can look normal even though it no longer seals. The result is draughts, higher heat consumption and condensation. From 1 October 2026, windows are, as a starting point, the company’s maintenance responsibility, so it makes sense to survey their condition as a whole.
Wet rooms and floor drains. Slow drainage, gurgling and drain smells can be early signs of a blockage. A dirty or poorly working floor drain can let water into the structure if the joint with the waterproofing is damaged.
Pipework and pipe supports. The condition of pipework is assessed on the basis of its age, materials, previous leaks and surveys. A loose or missing pipe support is also a risk, because an unsupported pipe moves and puts strain on the joints. A single leak does not tell you the condition of the whole pipework, but its cause needs to be found.
Ventilation. Ventilation may be working, but less well than designed. Stuffiness, a bathroom that is slow to dry and windows misting up can indicate blocked vents or filters.
Electrics. A loose connection can heat up for a long time without any visible symptoms. Fuses that keep blowing, overheating and a burning smell are always investigated straight away, and repairs are carried out by an electrical professional. More in the article electrical safety in a housing company.
Fire safety. Escape routes must be clear, fire doors must close and smoke alarms must work. Read more about smoke alarms.
Warning signs in maintenance records and fault reports
Some hidden defects first show up in maintenance and consumption data:
- The same fault keeps recurring. If the same drain keeps blocking, it is the symptom being fixed, not the cause.
- Maintenance keeps going back to the same place. What the visits involve and how often they happen say more about the condition of the property than the amount on the invoice.
- Several residents report the same thing. Draughts, unusual temperatures or smells in several apartments point to a building system rather than a single apartment. If draughts are reported from fifteen apartments, that is a different matter from a report from one apartment.
- Consumption changes without explanation. Weather, the number of residents and prices affect water and energy consumption, but a sudden unexplained change may point to a leak or an adjustment error.
- The result of a repair is not checked. The work is finished and the matter is closed, but did the problem go away? It is worth agreeing on follow-up for significant repairs.
Why defects stay hidden
The board meets a few times a year, the property manager looks after several properties and maintenance staff move around the building according to work orders. Most of the building, however, is used by residents, and apartments contain many parts that are the company’s responsibility: pipe joints, valves, floor drains, radiators, windows and ventilation terminals.
Not all residents report small things. They do not know whether it is the company’s concern, do not think the observation is important or do not want to bother the maintenance company. A tenant may assume the owner will deal with it, and the owner may never hear about it. Hidden defects are therefore often a communication problem too.
Nor does a visual inspection reveal everything. Moisture and microbial damage inside structures, the inner surfaces of pipes, the state of waterproofing or faults in the electrical system cannot be reliably assessed just by looking. They require a qualified expert and appropriate methods.
Responsibility, reporting and access to apartments
Responsibility does not depend on where the defect shows. Under chapter 4 of the Limited Liability Housing Companies Act (asunto-osakeyhtiölaki, 1599/2009), the company is, as a starting point, responsible for the structure, insulation and (from 1 October 2026) the windows, as well as the heating, electrical, data transmission, gas, water, drainage and ventilation systems and other similar main systems. The shareholder is responsible for the interior of the apartment, and the articles of association may provide otherwise. A moisture mark visible in an apartment may be caused by the company’s pipework, by a part that is the shareholder’s responsibility or by alteration work the shareholder has carried out. From October 2026, the law explicitly states that the shareholder is responsible for maintaining alterations they have made and for any extra maintenance costs they cause the company. Read more about the housing company division of responsibilities.
The shareholder must report defects. A shareholder must notify the company without delay of any defect or deficiency in the apartment that the company is responsible for repairing (chapter 4, section 8). From October 2026, this obligation also covers company spaces in the shareholder’s use where the right of possession is not based on the articles of association or a lease, such as the yard area in front of the apartment or a storage space made available to the shareholder. No technical diagnosis is needed; it is enough that the company is made aware of the observation. See reporting a fault in a housing company.
The law does not require apartments to be inspected. The board is responsible for organising property management properly, but the law does not oblige it to inspect every apartment at set intervals. The company does, however, have the right to enter an apartment when this is necessary to monitor its condition and upkeep or to carry out maintenance work. How such a visit is arranged is explained in more detail in the article on the housing company apartment round.
The board’s written report on maintenance needs for the next five years is based on the information the company has. A defect that has not been noticed cannot appear in the maintenance needs report.
From observation to decision
The following are practical recommendations, not statutory obligations.
Distinguish between observation, assessment and investigation. First, record what is seen, heard or smelled. Then assess whether the observation calls for further investigation, and if necessary have a qualified expert establish the cause and extent. This reduces both needless worry and the risk of problems being ignored.
Record observations. A hidden defect often emerges gradually: first a small discolouration, the following year a larger mark and then a smell. Without a record of the first observation, it is hard to see how things have developed. Record the date, location, part of the building, description, photo and follow-up action. More on this in the article on a housing company’s fault history.
Keep information in one place. If nobody knows when something was last inspected, what changes have been made in the apartments or why an old solution was chosen at the time, decisions rest on a weak foundation. Inspections, alteration notices and surveys belong in the maintenance log (huoltokirja), not in board members’ email inboxes.
Prioritise by risk. Observations related to personal safety, an active leak, electrics or fire safety are dealt with immediately. Unclear observations are assessed, and minor ones can simply be monitored.
Make reporting easy. Tell residents what to report straight away, where to report it and what information is needed.
Spotting a problem early does not always make the repair cheap. If the pipework is at the end of its service life, it has to be renewed in any case. But early information gives the company time to investigate, plan, put the work out to tender and arrange financing without a crisis.
Questions for the board
- Is our knowledge of the building’s condition based only on fault reports, or also on planned inspections?
- When were the building, the roof and the ventilation last inspected?
- Do we have recurring moisture or water damage?
- Are similar observations combined and compared with maintenance costs?
- Will the observations be kept when the board or the property manager changes?
- What do we currently not know about the condition of our building?
Frequently asked questions
Who is responsible for a hidden defect?
It depends on which part of the building is defective, on the articles of association and on what caused the defect. As a starting point, the company is responsible for the structure, insulation, windows and main systems, and the shareholder for the interior of the apartment.
Does every warning sign need to be investigated immediately?
No. Significance and urgency are assessed case by case, with an expert if necessary. An observation may simply be normal wear and tear.
Will an apartment round find all hidden defects?
No. A visual round does not replace a condition assessment, a condition survey or electrical inspections, but it does pick up observations that warrant further investigation.
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.
