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What’s the issue?

Oh, we love a hot shower, especially in the cold winter months. Perhaps we’re all guilty of occasionally turning the temperature up a notch and enjoying few extra minutes of shower time. It’s no crime of course but the steam and condensation can cause some problems if not managed right.

Few people have a complaint with the steam itself and many people absolutely love it. Anyone for a sauna? It’s when that steam turns into condensation that the problems can start.

Every winter we get questions around condensation in bathrooms and how to manage it. We’ve found that understanding the key factors involved helps us all to manage steam and avoid excessive condensation and mould. Here are a few pointers to keep in mind when planning, building or using your bathroom.

What’s the cause?

Condensation in its purest form is caused when humidity in the air meets a cold surface and it condenses from a gas to a liquid again. Whether it’s the outside of your cold drink or the inside of your windows, it’s the same process in action. Warm air can “hold” more moisture than cold air. As air cools, it will “shed’ the excess moisture by forming small droplets commonly visible as steam or clouds.

In our bathrooms we experience this as fogged up mirrors, windows and water dripping off surfaces.

What’s the issue with condensation?

The complaints are with mirrors fogging up and condensation literally dripping from bathroom surfaces. This should be avoided, both for your comfort now and to prevent much larger problems down the track.

The immediate symptoms are usually obvious: Steamed up mirrors are not useful, water dripping down walls and windows is unsightly and the room and towels simply never dry out properly.

The longer-term issues are permanent damage and health hazards. Water left to condense and sit on bottom edges of mirrors will eventually attack the edge of the silver backing of the mirror, causing it to discolour and peel. Permanent damp patches on walls and ceiling are an ideal place for mould spores to take hold and grow. The same will happen in shower alcoves that remain damp and don’t get the right frequency and methods of cleaning. Mould infestations are detrimental to our health and can be extremely difficult to eradicate, once they get hold

How do we avoid and manage condensation problems?

It all comes down to three key factors:

  • The amount of steam generated
  • Surface and air temperature of the room
  • Air flow

Prevention is always better than a cure, so let’s look at each of these factors play a part and what we can do to avoid problems in our bathrooms at home.

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What can affect the amount of steam generated?

  • Type of shower head. Large overhead rain showers generate far more steam than traditional shower heads.
  • Location (height) of shower head. Increased air gap (distance that droplets travel) leads to increased steam.
  • Water temperature. Thermal loss in the air gap also calls for hotter water at outlet. (This change is caused by us compensating for the thermal loss due to shower type and location)
  • Absence of a shower screen (enclosed shower means less steam as the air within the alcove is warmer than outside it)

The high volume of steam is not necessary a problem, but it needs to be managed with other factors.


What part do air and surface temperature play?

As noted above, condensation forms from warm, humid air on cold surfaces. Base level heating of a bathroom will make a huge difference to condensation. So, let’s look at what factors affect the temperature of your bathroom and what we can do to raise it.

  • Type of construction matters to your thermal efficiency (timber frame vs. brick veneer walls, concrete vs timber frame floors). Some construction methods are simply better than other at retaining heat inside. Insulation of the walls, ceiling and floor is vitally important for an efficient home.
  • Size and shape of the room, including ceiling height (overall air volume). Large rooms with very high ceilings can be difficult to heat.
  • Heat sources within the room. Floor heating, radiant and ducted heating within the room will all heat up the room itself. Most towel warmers are just that, while some are powerful enough to be room heaters, and lastly infrared heat lamps are designed to warm up the person standing under them, rather than the room.
  • Location of bathroom within the house. A central bathroom in the middle of a house will get the benefit of ambient heat from adjacent rooms, while one situated away from heated living areas will not get any such help.
  • Type and amount of heating in the rest of the home, which determines the ambient air temperature of the room and the temperature of the air being drawn in through ventilation.

What determines air flow?

To control steam, your bathroom needs a good rate of air flow. Natural ventilation through an open window is almost never sufficient. Mechanical ventilation (exhaust fan) of some sort is needed for good air flow

  • Type and capacity of exhaust fan (they vary enormously!)
  • Location of shower alcove in relation to air supply (room configuration)
  • Location of exhaust fan in relation to the shower and air supply. It’s best if air is drawn through the room
  • Type and size of air supply. This is preferably an air gap under the door. 10-15mm is usually ideal.
    Note that an open window in winter is counterproductive, as it draws in cold air which both cools the surfaces and is less able to hold moisture.

It doesn’t matter how good your ventilation is if you don’t use it appropriately. For best results, you should turn on the exhaust fan before turning on the shower and leave it on until the room is clear of steam and condensation.

Hints & Tips – For best results in reducing steam during winter

  • Be proactive – start with good design!
  • Ensure the exhaust fan type and location suits your bathroom
  • Ensure good air supply into the room
  • Keep a moderately warm home and warm room (perhaps leave bathroom door open if heating other parts of the home)
  • Turn on the exhaust fan before turning on the shower
  • Leave the fan on until the steam and condensation have cleared.

If you follow these tips, you should be able to turn the fan off as soon as you step out of the shower, with no residual steam or condensation in the room!

Thinking of a bathroom renovation? Contact us on 08 7122 6100 or visit our showroom.

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