Here, Tom Entwistle explains how to deal with a condensation problem.
It’s that time of year again. The first signs of the UK’s autumn cold arrives as we see more cooling rain and wind, and a noticeable drop in temperature. Time to bring out those stored away jumpers and up the temperature thermostat on the heating system.
As we look forward to even cooler temperatures heading into winter, we can anticipate problems with condensation in our tenanted properties.
Condensation is the bane of many landlords’ lives in the winter season. It causes black mould on walls and ceilings, it’s a serious health hazard and the cause of many tenant complaints – witness the many news reports in the media.
There’s also an added imperative on the horizon for private landlords because if the new Government’s intentions are realised Awaab’s Law will soon be applicable to private lettings, as it already is in the social housing sector.
The tragic death of little Awaab Ishak shocked the nation and brought the issue of condensation in homes to the public’s attention, as well as to the authorities.
What followed was Awaab’s Law introduced in July 2023 as part of the Social Housing (Regulation) Act. This legislation effectively inserts into social housing tenancies a term that requires social landlords to comply with new regulations, to be set out in detail through secondary legislation. If landlords fail to do so, tenants will be able to hold their landlords to account by taking legal action for a breach of contract.
Awaab's Law is part of a wider plan to reduce non-decent rented homes by 50% by 2030. Tenants will be required to report damp and mould promptly, and landlords will be required to fix any reported health hazards within specified timeframes. The law will also now apply in the Private Rented Sector and is expected to become law sometime this year.
Condensation occurs when warm moist (humid) air circulating in a home lands on colder surfaces and condenses into water droplets, simple as that. Warm humid air (steam being the visible example of this) is lighter than cold air so will rise to the highest parts of a home if allowed to circulate internally.
Once the warm air hits cold surfaces such as window panes, mirrors, tiles and even walls (plaster and wallpaper) and clothes in wardrobes, the water condenses out forming visible droplets or soaks into porous surfaces.
The result is – over time – the build-up of black mould. The result is a toxic fungus that may cause the human immune system to react. Common symptoms include sneezing, coughing, congestion and eye irritation. It rarely causes serious illness or death but may worsen asthma symptoms and can be more serious for those with allergies.
It also has a deleterious effect on buildings. Wallpaper and plaster will start to rot and disintegrate, and timber structures can start to suffer from decay and wet and dry rot.
Condensation is worst when certain conditions exist in a home. When:
When occupants fail to provide sufficient heating in a home over time walls become thoroughly cold and therefore water penetration goes deep into the fabric of the building. This makes the walls even colder, and a vicious cycle is created resulting in black mould on the surfaces.
These conditions may be exacerbated by poorly insulated homes and heating systems that are inefficient and expensive to run. Unfortunately, some tenants may skimp on heating to save money, however well insulated the home and however efficient the heating system.
Cooking and bathing are the major causes of warm steamy air. If condensation is to be prevented this steam must be vented out of kitchens and bathrooms as it is produced using extractor fans. Doors to these rooms should be kept closed at peak steam producing times and drying close indoors, especially on radiators, should be avoided at all costs.
There are several things that landlord can do to avoid condensation and black mould in their rental properties:
Modern houses – those build within the last 10 years or so – tend to be well insulated with cavity walls that are filled with good insulation, dry lined walls which add to the insulation’s effectiveness, underfloor insulation and sometimes underfloor heating, well insulated attic spaces and effective double if not triple glazing. With well sealed doors and windows preventing drafts you end up with a well-insulated sealed box, which in itself can be a condensation problem if steam is not properly vented.
Older houses – have the opposite problem. They are cold and draughty with poorly insulated – often with solid walls and no cavity – walls and with old inefficient oil or gas boilers, or open fires, log burners or storage heaters.
Older homes need to be brought up to modern standards with floor, ceiling and wall insulation, plus effective double glazing where possible. There are now some very effective internal and external wall insulation systems for properties with no cavity, while effective loft and floor insulation is usually easy to achieve. Widow and door replacements with modern draft proofing and double glazing are also relatively straightforward to up-grade.
These measures, while involving a substantial investment in some cases, will be necessary to meet the up-coming improvements in energy efficiencies being called for, especially the EPC rating of “C” likely before 2030.
It is important to provide a heating system that is efficient at maintaining a warm ambient temperature at a reasonable running cost. When tenants can’t afford to heat the home, that’s when condensation problems will arise.
Natural gas is still the cheapest fuel for a central heating system when this is available at the property through the gas grid. Oil and LPG comes in next and of course homeowners are being encouraged to install heat pump systems, but these only work well if the insulation is up to a high standard and there is room internally for the equipment necessary.
When the home relies purely on open fires, log burners or storage heaters, these are rarely adequate for a modern home and/or the cost more to run.
It is often cheaper to run a heating system continuously at a low temperature, say 19 degrees, than allowing the house to become cold and then basting with heat when residents return. There are inexpensive monitoring devices now available on the market, so landlords can check and record the temperature level being maintained.
It is vital that steam produced in kitchens and bathrooms is prevented from percolating around the home as it will rise to the highest points and condense on any cold surfaces it finds there. Most noticeably it will condense on windows but also it will soak into the porous surfaces in the fabric of the building, wallpaper, plaster and timber.
Window and wall vents are available which will work from a switch, a light switch, continuously running or will automatically activate when the humidity in the air reaches a certain level.
Tenants need to be educated on the importance of using these extraction systems. They must be dissuaded from blackening them in cold weather – checked on your regular inspections.
Ultimately, landlords can install a Centralised Mechanical Extract Ventilation (MEV) or one with additional heat recovery (MVHR) is a whole dwelling ventilation system that supplies and extracts air continuously at a low rate.
This is a low energy, continuous mechanical extract ventilation system designed with multiple extract points to simultaneously draw moisture laden air out of the wet rooms (bathrooms and kitchen) providing a quieter and more efficient system compared to separate fans. A central unit is mounted in a loft or cupboard and ducted to extract polluted air from the wet rooms of the house.
With the right approach there is no need to have any condensation and mould in a modern house. If tenants maintain sufficient ambient heat on a continuous basis, and they religiously vent out steam when they are cooking or when they wash, shower or bathe, the home will be free of this hazard.
Part of a landlord’s drive to achieve this is to educate their tenants so that they understand the causes and the remedies and prevention of condensation in their home.
Landlords need to explain these issues clearly to their tenants and put this in writing in the form of a condensation letter.
Here is an example winter condensation letter you might use:
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[Add your address]
[Add tenant’s address]
[Add the date]
Dear [Add tenant’s name]
Re: Winter Condensation Information
Condensation is a problem that occurs in homes mainly in cold winter weather. It results in back mould which can be injurious to your health. It must be avoided at all costs.
There are several causes for this:
If you take these simple precautions, you will avoid condensation forming on any of the surfaces in your home and there will be no dangerous back mould to damage your health.
If, however, you do find any signs of black mould, please contact [your lettings manager or landlord] immediately.
Yours sincerely
[Add your name]
Contact details: [phone, email contact and address]
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Sending out letters like these, explaining the main issues to your tenants will potentially prevent any problems you may have with condensation and mould. The letters will also provide good evidence that you are proactively addressing the issue, so keep copies of all the letters you send.
Condensation is without doubt a knotty problem and to some extent landlords are in the hands of their tenants in achieving a mould free home. Therefore, it’s worth making a big effort to educate your tenants about the issues and to monitor the situation through regular inspections. The authorities primarily will blame the landlord.
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