A Finlay Brewer Property Management Guide

THE PROBLEM

Condensation is by far the most common cause of dampness in homes. It affects both new and old properties.

Condensation is directly associated with mould growth and it is this that the occupier first sees and gives an idea as to the potential scale of the problem.  The mould is usually found on decorative surfaces, especially wallpapers, where it can cause severe and permanent spoiling.  The mould and it’s spores (“seeds”) cause the musty odour frequently associated with a damp home and can sometimes give rise to health problems.

The obvious places for condensation to occur is on cold walls and floors and around windows.

THE CAUSE

It is a fact that warm air can hold more water as a vapour than cool air.  So quite simply, condensation is caused when moisture-laden air comes into contact with a cold surface- the air is cooled to a point where it can no longer hold its burden of water vapour.  At this point, the DEWPOINT, water begins to drop out of the air and it is seen as condensation on surfaces.  On impervious surfaces such as glass and paint, beads or a film of water collect. While on permeable surfaces such as wallpapered walls the condensing water is absorbed into the material.  Therefore the problem is initially not obvious.

The main source of domestic condensation is people. In adult men, 60% of their bodies are water; 55% in adult women.  With every breath people release a small amount of water vapour and over a day this builds up to around 400g of water vapour created.

RECOGNISING CONDENSATION

Condensation is very much a seasonal problem which mainly occurs during the colder months (October to April).  During the summer the problem is SEEN to go away.  During the winter, ventilation of the house is usually low (windows and doors are closed, draught proofing takes place).  This allows a build-up of water vapour in the house which, in some cases, is  sufficient to cause condensation. So during the colder months the following signs appear: water droplets form on cold, impervious surfaces such as glass and paint; wallpaper becomes slightly damp (often not noticed); moulds develop, usually black mould (Aspergillus Niger). This frequently forms in areas where there is little or no air movement such as around windows, floor/wall and wall/ceiling junctions, behind furniture against colder walls, inside wardrobes against external walls and in classic triangular patterns in corners. 

In some cases condensation may be long term but intermittent, forming only at certain times of the day or night.  In these cases the only sign of condensation may be mould growth with water evaporating during the day. One should also be aware that the problem can occur well away from the site of most water vapour production. For example, water vapour produced in the kitchen may diffuse through the house into a cold bedroom where it will condense on cool walls and lead to mould growth.

WHAT ACTIVITIES CAUSE CONDENSATION?

Anything that releases water vapour into the air will increase humidity and eventually contribute to condensation.  Some of the most common contributors are:

Boiling a kettle

Cooking

Using a Washing machine or dishwasher

Hanging out wet clothes to dry

Drying clothes on a radiator

Bathing or showering

Breathing

These activities will contribute around 2.5KG of water in a day the equivalent of 10 glasses of water – into the air.  Without good ventilation in the home this will settle on windows, walls, and other cool surfaces as condensation and can quickly lead to damp and mould

THE SOLUTION

The control of condensation is based on two very simple primary measures.

IMPROVE VENTILATION. This will disperse the internal moisture laden air and replace it with drier air from outside (yes, external air is drier than internal air most of the year!)

Ventilation is achieved by opening a few windows, installing air vents, and using extractor fans.  However, it is most effective to remove the water vapour from where it is generated, e.g. kitchens and bathrooms. 

HEATING. Coupled with good ventilation, heating should be set to give a constant low-level background heat.  This will ensure no rapid changes to the environment, and will also facilitate slight warming of wall surfaces over a period of time thus reducing the risk of condensation.

It is useful to understand that dry air is cheaper to heat than damp air

Other steps to eliminate water vapour include not drying clothes on or by radiators and ensuring your tumble dryer is vented to the outside or ensure it is a condensing machine.

12 WAYS TO REDUCE CONDENSATION IN YOUR HOME

Condensation in your home can be a cause of damp and lead to unsightly black mould.  Aside from the risk to the fabric of your home, damp and mould from condensation can also lead to health problems, trigger allergies and make asthma worse.

To reduce the problem of condensation in your home you need to reduce the amount of moisture in the air.  There are several easy steps that you can take to do this:

Washing and Drying Clothes

Dry Clothes Outdoors

One of the simplest ways to reduce the amount of moisture in your home is to avoid drying clothes indoors.  Moisture evaporating from clothes as they dry or dripping onto the floor will condense on walls and windows.  If you are unable to dry clothes outdoors you should use your bathroom with the door closed and windows open.

Ensure Your Tumble Dryer is Correctly Vented

A single load in your tumble dryer can release 2 litres of water into the air as steam.  By ensuring that your dryer vents outside your house you can prevent this moisture from condensing on cold walls and contributing to damp problems.

Cooking

Close Kitchen Doors

Your kitchen is one of the rooms that contribute the most moisture in your home.  When cooking food you should ensure that the doors are closed to prevent the moist air from going into colder rooms where it will cause condensation to form.

Use Pan Lids When Cooking

Keeping a lid on pans when cooking is more energy efficient as less heat is lost and it also reduces the amount of moisture that is released into the air as steam.  If you have an extractor fan or hood in your kitchen you should ensure that this is running when you cook.   Your extractor fan should continue to run for 10-15 minutes after you finish cooking as there will still be moisture present in the air.

Bathing

Close Bathroom Doors

If you take a hot bath or shower steam will form in your bathroom that can escape into the rest of the house if the doors are open and cause damp in other rooms.  Make sure that you close your bathroom door when using hot water to keep as much moisture in the bathroom as possible

Use an Extractor Fan when Taking a Shower

Using an extractor fan when taking a bath or shower will remove steam and moisture from your bathroom and vent it outdoors.  This will immediately reduce the amount of condensation that forms in the bathroom itself and reduce the amount of moisture that can escape into the rest of your home.

Use Bathmats

Using a decent sized bathmat will help to avoid saturating bathroom floors when you are getting out of the bath or shower. The bathmat will help soak up some of the moisture, helping to reduce the condensation in the room.

Ensure Your Property Has Adequate Heating

Maintaining a consistent level of heating in your home will improve the temperature of walls and other surfaces where condensation can form.  Central heating from your boiler is more efficient than individual heating in each room.  You should avoid paraffin or portable gas heaters as both produce a lot of moisture along with toxic fumes. In these difficult financial times it is still important to maintain background warmth in your home.

Improving Air Flow

Do not Overfill Wardrobes & Cupboards

A lack of ventilation coupled with the moisture in the air trapped in warm overfilled cupboards can become a breeding ground for mould as the air is not able to circulate freely inside. A musty smell is a sure sign that the cupboard is overfilled.

Move Furniture Away from External Walls

Make sure that your furniture is at least 50mm away from the surrounding walls so that air can circulate more easily. Placing wardrobes against internal walls means that the temperature in the wardrobe will be slightly warmer and help reduce damp and mould problems. Don’t leave wardrobes, clothes racks, sofas or anything that blocks circulation up against external walls

Open Windows When it is Warm

On warm days, letting fresh air into your home can help improve ventilation.  If you use a room regularly and the weather is not cool, opening windows slightly will help keep air moving.  One of the biggest causes of condensation is moisture from our breathing so ensuring fresh air into your most frequently used rooms will help to avoid condensation.

Take the Water Out -Prevent Condensation From Forming

After using the bathroom or kitchen wipe down the tiles to take the moisture out of the equation, use a window squeegee to take water off windows and wipe away the moisture.

Using a dehumidifier and pouring the collected water in a basin or bath will remove damp air (particularly useful if you HAVE to dry washing indoors), not only do they remove water from the air but they will also reduce your heating costs as it is cheaper to heat dry air than wet air. This can help to reduce the amount of moisture that can form and will also reduce the risk of mould being able to grow.

Wipe down cold surfaces if you see moisture.

HOW MUCH CONDENSATION DOES A PERSON PRODUCE?

If you’ve ever woken up on a cool morning and seen droplets of water streaming down your windows then you have experienced condensation.  In our homes condensation is caused by moisture being released from humid air when it meets a cool surface.  The main source of domestic condensation is people, but did you ever wonder how much water vapour an average person releases into the air each day?

Here is how much water vapour is created by day to day activities

Breathing

Every day an average person breathes in around 14,000 litres of air, and with every breath, we release a small amount of water vapour.  Over a day this builds up to around 400g of water vapour created.  People who are active will breathe out more due to higher internal temperatures.  During the night, because we normally sleep with doors and windows closed, the concentration of water vapour in the air is higher and due to colder temperatures outside we are more likely to see condensation form on windows as a result.

Boiling a Kettle

Kettles contain most of the steam produced when boiling water although some will be lost.  Typically, during the two minutes or so it takes to boil half a litre of water to make two cups of coffee, about 10g of water (2%) is lost as steam.  If you make 8 cups of coffee or tea during the day this releases about 80g of water into the air.

Cooking on the hob

If you don’t use a pan lid when boiling food on the hob then the amount of water lost as steam can be much higher than with a kettle or a lidded pan.  If you are cooking pasta on the stove for 10 minutes in 2 litres of water you might create as much as 100g of water vapour.  Leaving a lid on the pan will reduce this considerably and help to get the water up to temperature more quickly, saving you energy as well.

Washing Machines and Dishwashers

The amount of water vapour released by a washing machine depends on the temperature of the wash and where the water is drained after use.  Cooler washes at 30C will release far less water vapour than hot washes, and use less energy, however an average wash could still release between 25-50g of water vapour.

Dishwashers usually work at a much hotter temperature than washing machines which means that they create a lot of steam, but they are sealed, so they don’t normally create much water vapour when in use.  If you open a dishwasher immediately after the cycle has finished then you will release a large amount of water vapour into the air quickly, however leaving the dishwasher to cool first will allow the steam to condense safely into the machine and drain away.  The cloud of steam released when a dishwasher is opened can contain as much as 20g of water which will increase humidity in a small kitchen considerably.

Drying Clothes or towels on a Radiator

Wet clothes are much heavier than dry - all the difference in weight is the amount of water that is left in the fabric after being washed.  A bath towel can hold as much as a kilogram of water and if this is dried on a radiator it can be a major contributor to household moisture levels.

Of course, drying clothes on a radiator isn’t just a major contributor to condensation.  It also makes your radiators less efficient at heating your home and allows a type of fungus called aspergillus to grow which can be harmful to the health of your household.

A tumble dryer is a more effective way to dry clothes, but it too will release a large amount of water vapour when in use.  If the dryer is properly ventilated then most of the steam will be released outside, but opening the door in use can cause a great deal of steam to form indoors.

Bathing or Showering

Taking a bath or shower releases a staggering amount of water into the air of your home.  On average, 1.7 kilos of water are released when bathing or showering, which is why bathroom extractor fans are so important.

The Total Water Vapour Created by a Person

If a person does the following over the course of a day:

Drinks 8 Cups of coffee or tea

Boils one pan of water for 10 minutes

Takes a shower

Uses the dishwasher

Washes and dries 2KG of clothing

Breathes normally

They will contribute approximately 2.5KG of water – the equivalent of 10 glasses of water – into the air.  Without good ventilation in the home this forms into condensation which will settle on windows, walls and other cool surfaces and can quickly lead to damp and mould.