How to prevent condensation in rented accommodation and whose fault is it?

Winters biggest problem is condensation – Nick Lyons of No Letting Go Inventory Management looks at the problems of determining the fault at the end of a tenancy and how to prevent it occurring.

Over the many years of dealing in rented properties, handling property visits and check outs one of the most common causes of debate in winter months is the issue around condensation and whose responsibility it is.

Many tenants report dampness to Landlords or agent which turns out in fact to be condensation.  This happens when warm air comes into contact with a cold surface and moisture in the air turns into droplets of water.

If your home has condensation, you may find a blackish mould growing on the inside face of external walls, in the corners of rooms, on window frames and behind wardrobes and other furniture.

Condensation is probably one the main reasons why a full deposit is not returned to a tenant at the end of the tenancy period.  This is because it is the responsibility of the tenant to take all reasonable steps to adequately ventilate as well as heat the house.

If any appreciable condensation develops, the tenant is normally expected to wipe down and clean the affected surfaces from time to time to prevent the growth of mould and any other associated damage that can caused to the window frames, floor, walls and ceilings.

You can reduce the risk of condensation by doing the following:

1. Open a window when you are cooking and keep lids on saucepans.

2. Leave the bathroom window open after a bath or shower to clear steam.

3. Keep the bathroom door shut when you are having a bath or shower.

4. Do not block air vents of airbricks.

5. Open windows in all your rooms for a few minutes each day to let some fresh air circulate.

6. Leave some background heating on all day in cold weather.

7. Do not cover radiators or storage heaters with damp clothing.

No Letting Go Inventory Management, the UK’s premier always advise our clients to inform their tenants of these issues and more over suggest that you put a clause into your tenancy agreement to cover this issue.

Property visits are crucial in catching these and other problems early. Advising tenants before the condensation becomes an issue with the property and creates wasted management time in dealing with the problems when it is too late is an area we strongly advise our clients. We see this so often in winter months that a simple clause and advise from an inventory clerk during the mid term property visit during the tenancy saves lots of money at a later stage.

If you are interested in the premium inventory management services offered by No Letting Go to local landlords and letting agents in your area visit the No Letting Go web site, www.nolettinggo.co.uk or contact us centrally on 0845 659 9980 / email info@nolettinggo.co.uk.

Further Facts About Condensation (extracted from BS 5250 (1975)

Condensation has become of the most common causes of dampness within buildings.  A Report of the Building Research Establishment estimates that one and a half million homes in the UK are badly affected by condensation.

Condensation occurs when moist air is cooled that it no longer has the capacity to hold water in vapour form.  Typically this can be seen to occur at cold surfaces such as window panes as mist or cold water pipes as droplets of water.

A brief summary of the terminology: The amount of water (or moisture) which can be held by air, (the humidity) depends on the air temperature.  The warmer the air the more water (or moisture) it can hold.  Cold air at 0 C is unable to hold any moisture.  The temperature at which the air cannot hold any more moisture is described as the dew point.  The dew point is the point at which condensation occurs (water or moisture that was in the air has condensed to liquid on a surface that was or at below dew point).  As the air temperature increases the dew point temperature will be determined by the amount of moisture in the air.  The relative humidity is the amount of moisture in the air relative to how much moisture the air can hold at that temperature.  So, at any given temperature, increasing the moisture in the air will increase the dew point temperature.  As the humidity increases the relative humidity increase and the risk increases that relative humidity will reach 100%.  Dew point temperature occurs when relative humidity reaches 100 % (and vice versa).  The inter-related nature of temperature humidity relative humidity and dew point can be send from examination of a ‘psychrometric chart’.

Some points to consider

The amount of moisture within the air in a building varies continuously.  Certain lifestyle activities generate moisture and these will increase the amount of moisture in the air.  Examples of these are cooking, drying clothes, bathing and even breathing.  Such activities need not always produce a condensation problem. The moisture can be dispersed out through an open window or extractor fan, or it may condense on a nearby window pane and be easily wiped away.

It is to where the moist air goes and the temperature of the places it goes that will determine whether a condensation problem is produced.

When the air is heated throughout the property the air is capable of holding moisture as vapour to the extent that can be seen from the psychrometric chart.  Most properties are not heated to the same temperature all the way through all the time.  For example, it is not unusual to hear living room to a higher temperature than a bedroom.  This means that the air in the living room can hold more water vapour than the air in the bedroom.

Typically moisture generated in a kitchen and bathroom might be allowed to escape through the whole house.  This might typically result in some local visible condensation in the kitchen and bathroom, no signs of a problem in the living room but some damp patches and mould growth on the external wall of a back bedroom.

Unless a study is made of the varying temperatures and humidities within a property it can be difficult to predict whether the property is likely to be affected by a condensation problem.  The factors that cause the problem, vary all the time.  It is certainly true that the tendency in recent years to draught proof houses and insulate to conserve energy has reduced the amount of air (and therefore airborne moisture) escaping to the outside.  This has had the effect of increasing the overall humidity levels.

The reduction in ventilation and increase in humidity can also encourage the growth of mould fungi.  These are often the first visible sign that a problem is present.  Relative humidity does not require to be as high as 100 % for mould growth to occur.  Mould growth can occur when the relative humidity is around 70 %.  This often happens in a part of the property that is less well heated and where the ventilation is reduced.  For example, a cupboard or wardrobe on the external wall of a back bedroom.  Although there may not be a visible wetness due to condensation.  The temperature in this location may not be as consistently high as that throughout the house, and as a result the relative humidity can be locally increased to above 70 % at certain times of the day.  That can be sufficient to support mould growth.

It is fairly easy to spot a condensation problem when there is visible evidence of moisture on a window or cold water pipe.  Fungal growth (usually moulds) can occur before the problem is visible in that way.

The conditions, which produce condensation and related problems of mould growth depend also to greater extent on the temperature and humidity of the air outside the building.  It is not uncommon therefore for a house to be affected by condensation or mould growth only at certain times of the year.  In such cases it would be unlikely that altering the ventilation alone would be sufficient to reduce or eliminate the problem.

A successful strategy for combating condensation will usually depend on a number of factors.  Since these will be most likely to produce a successful result.

Four Essential Elements Need To Be Considered

(1) Reduce humidity

(2) Improve air circulation  

(3) Improve insulation 

(4) Improve overall background heating

There are a number of ways of dealing with each factor and the most appropriate will depend on the individual property.  It is generally true that more than one factor will require modification.

It makes good sense to start with the simplest and least expensive option which typically might be the installation of extractor fans in kitchen and bathroom, the places where most of the airborne moisture is generated.

A monitoring period should be allowed after each course of action is taken so that the contribution of each factor can be evaluated.

Contact No Letting Go on 0845 659 9980 for more information visit our webssite for inventory services throughout the UK