Why damp is Batumi's most common flat problem
Ask Batumi owners about problems with their flats and damp comes up again and again: black spots in the corners, a musty smell in wardrobes, peeling paint around windows. The cause is not bad luck. Batumi is one of the most humid cities in the region, and a flat that is closed, cold or poorly ventilated will collect moisture. The good news is that damp is mostly preventable, and that the warning signs are easy to spot if you know where to look.
This guide goes deeper than our general advice on building quality and winter: it explains why condensation forms, what the law says about new buildings, how to keep a flat dry and what it costs, how to spot hidden mould at a viewing, who pays when a rented flat is damp, and what insurance does and does not cover.
How humid Batumi really is
The national climate code for building design gives month-by-month humidity for Batumi city. Average relative humidity rises from 76% in January to 85% in September and 86% in October, with an annual average of 81%. Even at one in the afternoon it averages about 70 to 73%. In other words, autumn, not winter, is the dampest season, and the outdoor air is almost never dry.
| Period | Relative humidity |
|---|---|
| January | 76% |
| September | 85% |
| October | 86% |
| Whole year | 81% |
| At 13:00, coldest and warmest month | 70% and 73% |
From the same code's figures for water vapour in the air, we estimate the average outdoor dew point at about 2.5°C in January and about 19.7°C in August. That points to two different damp seasons: in winter, moisture condenses on cold walls and windows; in the muggy summer, it settles on cold surfaces near air conditioners and in flats shut up between guests.
Why moisture appears on walls
Air holds moisture as vapour until it touches a surface colder than its dew point, where the vapour turns to water. By our calculation, air at 20°C has a dew point of about 9.3°C at 50% humidity, but about 14.4°C at 70%. Mould does not even need visible water: a thermal-break manufacturer explains that it can start where the humidity at a surface reaches about 80%, which in a room at 20°C and 50% happens on surfaces at about 12.6°C.
Put those numbers together and the Batumi problem becomes clear. In a flat at 20°C and 70% humidity, which is easy to reach without heating or dehumidifying, any corner, window frame or balcony slab a few degrees colder than the room is already in the zone where mould grows. The usual culprits are the edges where balcony slabs pass through the wall, uninsulated corners on the sea side, window frames and the backs of wardrobes on outside walls.
What the rules require of new buildings
A government decree of 13 July 2021 sets minimum energy efficiency requirements for buildings. Batumi falls in climate zone 1, where outside walls may lose no more than 0.5 W per m² per degree and windows no more than 2.2. The decree says low inside surface temperatures and condensation must be avoided in all cases, requires thermal bridges to be included in the calculations, and sets a limit for air leakage in flats.
The catch is the date. These rules apply only to buildings whose construction permit was applied for after 30 June 2022, and later amendments kept that cut-off. Most towers on the market today were designed earlier. Separately, the Law on Energy Efficiency of Buildings of 2020 requires an energy performance certificate when a building or flat is sold or rented, valid for ten years. For a new-build purchase, ask the developer whether the project falls under the 2021 decree and for its energy documents.
Why it matters for health
The World Health Organization's guidelines on dampness and mould, published in 2009, conclude that the key is to prevent or minimise persistent dampness and microbial growth. WHO Europe reported that people living in damp or mouldy buildings face up to a 75% greater risk of respiratory symptoms and asthma, and that 13% of childhood asthma in the European region can be attributed to damp housing. The guidelines place insulation and the building on the owner, and heating, ventilation and water use on the occupants.
Keeping a flat dry
The US Environmental Protection Agency advises keeping indoor humidity below 60%, ideally between 30 and 50%, drying any leak within 24 to 48 hours, and never painting or caulking over mould. In Batumi, where outdoor air averages 81%, opening the windows alone will rarely get a flat to those levels; heating, an air conditioner on its drying setting or a dehumidifier does most of the work.
- Measure first: a simple hygrometer shows whether a room is above 60%.
- Run a dehumidifier: a major Georgian retailer listed household units at about GEL 450 to 700 in October 2026; a 10 litre-a-day unit is sold for rooms up to about 35 m².
- Use the air conditioner's dry mode in the muggy summer months.
- Ventilate kitchens and bathrooms after cooking and showers, and dry laundry outside or with a dryer.
- Leave a gap of a few centimetres between furniture and outside walls.
- Keep a closed flat dry: a dehumidifier on a timer or a low heating setting while you are away.
Running costs are modest. As our own example, a 250 W dehumidifier running 12 hours a day uses about 90 kWh a month, which costs about GEL 21 to 25 at the electricity tariffs in force since April 2026.
Spotting hidden mould at a viewing
Sellers sometimes repaint just before a viewing, so look beyond the walls. The most revealing months for a viewing are September to November, when outdoor humidity is highest, and January and February, when cold walls condense most.
- Open built-in wardrobes on outside walls and smell the inside.
- Look behind beds and sofas placed against outside walls.
- Check the ceiling corner where the balcony slab meets the wall.
- Lift the edges of rugs and check the window sills and frames for staining.
- Be wary of fresh paint in only one corner or one room.
- Ask the owner and the neighbours directly whether the flat has had damp.
The US agency notes that if mould is visible, testing is usually unnecessary; the question is where the moisture comes from. It also suggests that small patches, below about 0.9 m², can be cleaned by the owner, while larger areas need professional help.
Damp in a rented flat: who pays?
Georgia's Civil Code divides responsibility clearly. Under Article 532 the landlord has to deliver a flat that is fit for its purpose and maintain it that way throughout the lease. If it has a defect, the rent is reduced by the amount the flat's fitness is diminished, though minor defects do not count (Article 536). If the landlord delays fixing a defect, the tenant may fix it and claim the cost (Article 537). A tenant who knew of the defect when signing and said nothing loses the right to a rent reduction (Article 538), and any clause limiting the landlord's liability is void if the landlord hid the defect on purpose (Article 539).
Tenants have duties too: they must tell the landlord about a defect immediately (Article 543) and carry out current repairs at their own expense (Article 548). And if a home is in a condition that seriously endangers the health of those living in it, the tenant may end the lease without notice (Article 542). We found no Georgian court case applying that article to mould. In practice, landlords should photograph and fix damp before letting, and tenants should record any damp at move-in. Our guide to rental law for landlords covers the wider rules.
What insurance covers
Home insurance is not a solution for damp. The home policy of one Georgian insurer, GPI, in its 2025 wording, excludes damage from dampness, water coming in through windows or doors or through openings caused by wear or construction defects, and rain damage to balconies. It covers sudden events such as leaks from a neighbour or a burst pipe. It also excludes any loss that occurs while the property has been left unattended for more than 30 days, which matters for owners who close a flat for the winter. Read your own policy for the same clauses; our guide to property insurance explains the options.
Damp in Batumi: what helps and what does not
| Helps | Does not help |
|---|---|
| A dehumidifier or air conditioner's dry mode | Opening windows on a humid day |
| Keeping indoor humidity below 60% | Painting over mould |
| Gaps between furniture and outside walls | Drying laundry indoors without ventilation |
| Regular visits to a closed flat | Leaving a flat shut for months |
| A newer building under the 2021 energy rules | Relying on insurance to pay for damp |
To be added by the team: photos for the team to take: a hygrometer reading in a flat, a dehumidifier in use, condensation on a window in January, mould at a balcony slab corner, and a wardrobe on an outside wall.
Dealing with damp step by step
Measure the humidity
Aim for 40 to 60% indoors.
Find the source
Leak, cold wall or indoor moisture.
Fix leaks fast
Dry within 24 to 48 hours.
Dry the air
Dehumidifier, heating or dry mode.
Clean small patches
Larger areas need a professional.
Record and report
Photos for landlords, tenants and insurers.
Frequently asked questions
How humid is Batumi?
Average relative humidity is 81% a year, highest in September and October at 85 to 86%.
Which season is worst for damp?
Autumn for humidity, and winter for condensation on cold walls and windows.
What indoor humidity should I aim for?
Below 60%, ideally between 30 and 50%, as the US Environmental Protection Agency advises.
How much does a dehumidifier cost?
About GEL 450 to 700 at a major Georgian retailer in October 2026.
Do new buildings have to prevent condensation?
Yes, under a 2021 decree, but only if the permit was applied for after 30 June 2022.
Who pays for damp in a rented flat?
The landlord must keep the flat fit for use; the tenant must report defects and do current repairs.
Does home insurance cover mould?
Usually not; one Georgian policy excludes dampness and losses after 30 days unattended.
Can I clean mould myself?
Small patches, yes; larger areas need professional help, and never paint over mould.
Sources
- Building climatology code PN 01.05-08, Legislative Herald of Georgia
- Government Decree No 354 of 13 July 2021 on minimum energy efficiency requirements, as amended by Decrees No 283 of 3 August 2023, No 328 of 30 August 2023 and No 229 of 20 June 2025, Legislative Herald of Georgia
- Law on Energy Efficiency of Buildings, Legislative Herald of Georgia
- WHO guidelines for indoor air quality: dampness and mould, and press release, World Health Organization, 2009
- A brief guide to mold, moisture and your home and mold course, US Environmental Protection Agency
- Humidity, temperature and condensation control, Schöck
- Civil Code of Georgia, Legislative Herald of Georgia
- Policy Comfort terms and conditions, GPI Holding, version of 1 February 2025
- Dehumidifier listing and second dehumidifier listing, Alta (accessed 27 October 2026)
- New electricity tariffs, First Channel, 30 March 2026, and average weather in Batumi, WeatherSpark
Change log
- - Guide published from the building climate code, Government Decree No 354 of 2021, the Law on Energy Efficiency of Buildings, the World Health Organization, the US Environmental Protection Agency, Schöck, the Civil Code, GPI Holding, Alta, First Channel and WeatherSpark.