Who’s Responsible For Mould In A Tenanted Property?

Mould in property can cause serious health issues and therefore, if found in a tenanted property, should not be ignored by either landlord nor tenant.  The mould fungi have been identified as the source of many health risks such as asthma, allergies, infections and sinusitis. Moulds produce allergens, irritants, and in some cases, toxins that may cause reactions as well as being unsightly.  And, it’s not uncommon – according to a recent housing survey by Shelter, 61% of renters have suffered damp, mould or leaking roofs.

The laws and rules surrounding the management of mould within tenanted properties aren’t clear cut, so when it comes to deciding who’s responsible for removing the mould and fixing any afflicted areas, it can result in disputes between landlords and tenants.

What causes mould to appear?  

The main causes of mould include; water leaks, penetrating or rising damp, wet or damp basements or crawl spaces, condensation, excessive water vapour or steam being generated through cooking, washing, bathing, showering and clothes drying, inadequate ventilation and/or heating.

Who’s responsible for dealing with mould?

For mould to be the landlord’s fault, it will usually have been caused by something that’s wrong with the build of the house, such as structural defects, leaking pipes, or ineffective damp-proofing. This may be different in commercial properties where the tenant may take on repairing responsibilities.

The most common cause of mould is through condensation and this is typically caused by the tenant’s lifestyle. For example, lack of proper ventilation, not opening windows or using heating. They should be regularly airing the property to prevent the growth of mould.

What can landlords do to prevent mould?

Looking from the outside of the property, a landlord should first check for obvious structural defects, that the walls are not suffering from rising damp, is there a presence of a damp-proof course?  Check that any wall cavities are clear of debris and that airbricks are clear and perhaps consider fitting additional airbricks to ventilate under suspended floors.  Ensure that the roof tiles are in good condition and no leaks are present. Inspect the guttering and down pipes, make sure that they are carrying the water away from the property or into adequate drains.  Solid concrete floors are prone to damp so may require a damp proof membrane.

What can tenants to to prevent mould?

When checking a tenant into a property, we always advise going through the inventory with them room by room.  At this point, it is a good idea to educate them on the causes of mould and how little lifestyle choices can make a big difference to their living conditions, health and comfort.

For starters, after a bath or shower, the room should be ventilated to the outside, not to the rest of the house – just opening a window (and closing the door) will help.   You as the landlord may also wish to fit an extractor fan.

Advise tenants to dry clothes outside on a line (if possible) or in a cool area of the property (although this may take longer, less moisture will be held in the air at any one time).  If the tenant chooses to dry clothes indoors, they should ensure that there is plenty of ventilation in the room. If they are using a tumble dryer, the dryer should ideally have external air extraction.  When people come in with wet coats and umbrellas, they should be hung or placed outside the living area to dry – like the porch.

Difficulty finding proof

The problem with mould in your buy-to-let property is the difficulty of identifying the person at fault. It can be tough to prove whether the mould was caused by a structural defect or simply a lack of ventilation.

In particularly difficult cases, a damp expert can be called in to assess the property and make a report that can be used as proof of the party at fault. They can also recommend the best ways to remove the mould and prevent it from growing again.

Have your say:  

Have you experienced mould in let property?  How was it handled?  What was the cause? Do you have any tips for our landlord readers in how to prevent mould?

About Jonathan Daines

After having worked as a high street letting agent for over 5 years, I believed there was a better way of helping landlords find tenants without the unnecessary expenses. And so in 2008, lettingaproperty.com was born and has since let over 8,000 properties across the country. I am very proud of the service levels we offer and to have achieved a 99.3% recommendation rate on reviewcentre.com. If you have any questions about our business, please do let me know. I look forward to hearing from you.


    January 1, 2016 REPLY

    I am sorry but there are some misleading elements in the article.
    I am a landlord and a qualified remedial building surveyor who used to do
    expert witness work in relation to such defects.

    Black Mould can only grow on clean water and will not grow on water that
    results directly from rising damp or penetrating damp. So if you find mould, the
    water source can only be condensation or a water leak on the affected wall.
    However, the excessive water vapour causing the condensation may be a construction related issue resulting in high levels of water evaporation into the property.

    This is a very important point as often the area where the moisture is being
    created is not the area affected by the mould. Plenty of properties suffer from
    rising / penetrating or defect related damp without getting a mould problem.

    The primary issue is the balance between the heating, ventilation and

    The common response of “just open a window” is not helpful.
    Condensation is the result of warm moist air being cooled to the point where it
    can no longer support the moisture it contains. When you watch a weather forecast and see a warm front meeting a cold front it results in rain as the air temperature on the warm front drops below “dew point”. Exactly this will happen when a window letting in cold air is confronted with warm moist air attempting to exit the property. Then there is the issue of security. Leaving windows open or on first lock position is often not possible for security reasons.

    The other gem is “they leave cloths to dry on the radiators”
    In the winter months or in flats without gardens or separate utility rooms, I’d
    question the landlord as to where else they expected their tenants to do it?

    In my properties I provide a telescopic drying rack over the
    bath or adjacent to the shower, well located humidity controlled forced
    ventilation, and effective bathroom heating. This then becomes the “laundry

    Ventilation in properties suffering from condensation should be via insulated
    air bricks such as Passy Vents. The primary moisture production areas such as
    the kitchen, utility room and bathroom should be force ventilated with humidity
    controlled extractors. Do not skimp. If you’re paying less than £100 for
    the fan its probably not up to the job as it will have a cheap and ineffectual
    humidity sensor and low quality bearings that will soon become noisy and
    encourage the tenant to switch off the fan. I put fans on a fused spur so they
    cannot be turned off without removal of the fuse.

    In properties with a roof void, I would recommend a centralised positive pressure
    fan system located in the stair well ceiling. This combined with passive
    ventilation in the other rooms will encourage the proper air flow.

    In bathrooms an axial fan is only suitable for outside walls. If there is any length
    of ducting that the fan has to push air through, it is essential that a radial
    type fan is used. Axial fans cannot push air very far down a 100mm diameter tube.

    The most important thing is to use mouldicide paint on all surfaces suffering
    from mould. Most “anti mould” paints don’t work. This is because they
    are normal paint with a simple liquid additive in them. This additive separates
    out in the tin resulting in uneven coverage and has a high vapor presure so it evaporates off over time.

    If you have to use an additive (to colour match) then get it vibration mixed in on
    the day of use. I prefer paints which have the mouldicide ground into the body
    of the paint. I use Silexine paint but I believe there are similar products

    Avoid wall paper, but if you absolutely must use it, then use a PVA based
    wallpaper paste. Normal starch based paste will provide a food source for the
    mould which is why mould often grows behind wallpaper.

    You can’t treat mould effectively on tile grout, silicone or rubber window gaskets
    without regular maintenance. A surface applied mouldicide such as
    “Dentolite” should be used minimum fortnightly on all surfaces which
    are suffering the problem. The surface should be cleaned, dried and then the Dentolite applied and left to dry. Maintenance of showers and bathing areas should be weekly.

    If the issue is severe, then the only recourse is to insulate the affected
    walls. This can be expensive and a minimum of 35mm insulation board is required (50mm high density Thermal Board preferred). On a straight run of wall it’s a simple task but in bay windows and areas where radiators require repositioning, it can be costly. Thermal board is particularly useful behind wardrobes or lining the back of fitted wardrobes on outside walls to help prevent mould on clothes and shoes.

    Most people heat their properties badly. In the morning it is heated, during
    the day the heating is off, in the eventing it is heated and at night the
    heating is off. This causes peaks and troughs which result in condensation. A
    wall will not warm up as quickly as the air surrounding it so the warm air
    collects moisture but where it comes into contact with the cold wall the
    temperature drops and the water is deposited as condensation. Constant 20c+
    back ground heating is a far more effective way for dealing with condensation.
    It is extremely expensive at first but as the property dries out, the costs
    will begin to balance against peek and trough heating. For this to work the
    heating system must be efficient and well planned out. Professional advice
    should be sought on this issue.

    If you have a problem tenant then there are humidity controlled fans which will
    link to a laptop and allow you to down load data on usage, power on and off,
    humidity and temperature. This will show if the tenant has been switching the
    fan off and or not maintaining the temperatures as recommended.


    On the legal issue of who’s fault is it? Mould is a health risk so it needs to
    be addressed. I have never had a situation where an environmental health
    officer is involved and they have not insisted on repairs.

    The main source of information is the landlord and tenant
    act but further reading is advised:

    Directive 2002/91/EC of
    the European Parliament and of the Council of 16 December 2002 on the energy
    performance of buildings

    In truth the lack of knowledge in courts and poor representation for the tenants / landlords often results in the cases failing, usually on a technical issue such as reporting procedure. However, for me the issues and cost of high
    turnover of tenancy in problem properties is simply not worth it. In most
    instances once a problem is identified I will do my utmost to ensure it is
    resolved in order to minimize tenant turnover and maximize profit.


    November 7, 2015 REPLY

    A number of questions arise:
    1. Complaints of condensation and subsequently mould are not distinguished from mould caused by defective premises. The former tenant life style the latter the landlord. It is common for both parties to confuse causation in their favour.Dampness itself may cause condensation due to lifestyle and result in mould. Tracing is therefore a point of dispute due to the time line.
    2. If the property is defective eg a leaking pipe and ,mould developed clearly as a consequence t(see above) then the landlord could be said to be at fault. If the damp if the damp is outside the demise of the property in question say an adjoining flat or retained parts then the long lease tenant can find against his landlord or his superior landlord.
    3. Condensation / damp / mould may be deemed to result from “the flat” as demised but in fact are inherent defects. In a case against a housing association (can’t remember the citation but well know example) the tenant complained of ingress of water and it was held that the landlord could not be found responsible for inherent defects as there was no disrepair. (S4 Defective Premisses Act 1972 distinguished).
    4. A word of caution – there is much legislation and case precedence, each case must be determined on the facts and applied or how they are applied and the claim or counter-claim made, Distinctions and confusion arise by untrained or trained persons on a. Fit for Purpose Cavalier v Pope, Warren v Keen, Robbins v Jones; ” Fit for Habitation” S11 1985; Hazards and potential hazards Housing Act 12004, Assumption of right and obligation to remain in possess regardless of express breach in S8 HA 1988 S21 Disrepair and deregulation Act 2015.

    Good luck !!

      November 9, 2015 REPLY

      It is commercial property with full internal repair obligation on tenant .who is to blame in such case . Please comment
      Tenant obligation to pay service charge for the external common area .
      First thought Water engresses from balcony walk way above the commercial property (common area) Caused damp and mould in the commercial property toilet area.
      Tenant complained to landlords and
      Landlord repaired externally as much as possible but window to the flat was not checked as it did not belong to the landlord .
      After extensive investigating it was found the engress of rain water was from the faulty / damage ( hair line crack ) in the seal of window from flat above . Window was replaced by the tenant at his cost . Tenant had a 99 year lease . Window belonged to the landlord but by replacing without landlord consent the tenant had the responsible to maintain .
      Commercial property downstairs waited three years to complain to law.

      November 9, 2015 REPLY

      Thank you Stanley, some great points raised here. I’ll be sure to review the cases mentioned above and agree that each case will be judged on the facts at hand. Appreciate the comments.

    November 7, 2015 REPLY

    i have solid walls in one of my properties and consequently no cavity insulation, hence the walls are cold and often below the dew point. my solution is to use thin sheets of polystyrene glued to the external walls, it works and its cheap.

    November 7, 2015 REPLY

    One useful way of minimising condensation and hence mold, is by installing a dehumidifier. You will be suprised by the volume of water they can take out of the air and the running costs are suprisingly low..
    It also gives you a good supply of demin water for steam irons.

      November 9, 2015 REPLY

      Thanks B Golden. I would suggest however, that you offer the tenant some sort of “gesture of goodwill” on their additional electricity costs if they were to run the dehumidifier. Here’s a handy chart showing the cost of operation: http://www.sust-it.net/dehumidifier-running-costs-energy-efficiency.php

        November 10, 2015 REPLY

        When you look at the load figure for the unit, and remember it does not run all the time,
        the cost is pennies. A flat screen TV takes more power, and is usually on as long.

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