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September Edition 2017

Condensation & Black Mold.

‘Winter is Coming’ is a popular TV catch phrase but unlike ‘Game of Thrones’ we’re only defending against cold, damp and sometimes icy weather. As the season turns to Autumn there’s another demon that reappears: Condensation followed by Black Mold.

Over the warmer months we don’t notice it but unless you’ve gone out of your way to prevent it the chances are very high that your home has this problem in the cooler months……and it doesn’t want to go away.

I got so fed up of having to wipe up wet window sills and soaking windows that a few years ago I decided to do something about it. The following explains what I discovered and how I’ve significantly reduced the problem without much cost.

The underlying discovery is that unless you live in a modern house our homes all share a common design flaw:

A Warm House, Poor Ventilation & Poor Insulation creates Condensation and then Mould.

Why do anything about it ?

A wet environment is not good for your health, we need a certain amount of moisture but not the amount where condensation frequently appears.

The black mould is also bad for your health and it thrives in warm wet environments. Unfortunately once it’s established it’s not very easy to remove.

You can clear the surface with a shop bought ‘mold spray’ or use a combination of first cleaning with diluted bleach, then with diluted vinegar and finally bread soda to get the longest break. It returns because the bacteria gets into the actual fabric beneath the surface and the environment is perfect for its growth.

Water….where is it coming from?

The condensation moisture comes from our indoor lifestyle and typically includes cooking, bathing, drying clothes and from the simply act of breathing. Our desire to keep warm in winter means we try to seal our houses to prevent the cold air from coming in, and of course we turn up the heating. What we don’t tend to do is expel this wet used air so it’s trapped and builds up in our homes.

Why does condensation form ?

Hot air is able to hold lots of moisture. Simply boil a kettle and you’ll see the steam rise, boil it dry and the water it once held is now in the nearby air. When that air cools its ability to hold the moisture drops and if that wet air meets a sufficiently cool surface then condensation appears. Depending on how much moisture is in the air you’d be surprised what surface temperature will cause condensation.

Purchase a ‘relative humidity’ meter to identify how much of a problem you have. Relative humidity indicates how full the air is with moisture at a given temperature and ideally your home should be between 40% to 60%. Outside this range is a breeding environment for Virus’ or bacteria.

If your reading is 80% at 20 degrees a dew point chart will tell you that if the air cools or meets a surface of just 16 degrees then condensation can form since the air is no longer able to hold it.

Why is it that only the windows get wet ?

The unfortunate truth is that it’s not only your windows getting wet but also the walls, blinds, ceilings, curtains, clothes, books…everything, it’s just more obvious on the windows and in larger amounts. Wherever wet air meets a cooler surface condensation forms.

The windows suffer the most since they’re high on the wall and not very good at keeping warm especially through a cold night. Therefore warm wet air is in contact with a cold surface.

If you have the original double glazing you’ll discover that it is of very poor quality compared to modern advancements and those that have recently replaced them probably see a noticeable difference.

3 Ways to Reduce Condensation.

1. Lifestyle Changes

How we chose to live is creating these issues. There are a few some simple, often free, changes we can make before considering any expensive building changes.

The aim is to reduce the amount of water you put into the air by:

Covering pots whilst cooking.
Opening the window and close the door when you shower or bath, and for a long while after.
Drying clothes indoor either by a externally vented drier or in a closed room with the window slightly open.
Fitting and using extractor fans in the bathrooms and kitchen. Some work on timers, movement, or even better get one with a humidity sensor.
Using a dehumidifier to collect the moisture from the air at the source.

2. Increase surface temperatures

It might seem obvious but your house cools significantly at night and in winter your windows are just above freezing. If the ceilings aren’t well insulated, especially where they meet the wall, it means that they get very cold too and this is exactly where you’ll find the black mould.

Prevent cold surfaces:

An extra layer of insulation across the attic and especially along the edges will keep the ceiling warmer. Apply coving to help insulate the ceiling edge where it meets the wall to give this weak spot extra insulation.

Our walls have the minimum levels of insulation but the builders often take a shortcut and don’t install plastic sleeve pipes to join the inside and external air vents. They save a few euros but this means that the cold outside air enters the wall cavity and cools your internal walls making the insulation less effective. If you can feel cold spots on the plaster board around the air vent then it’s likely that a simple pipe will remove it.

The wall surrounds of windows are another weak spot where again it’s likely to have no insulation and poor filling of outside gaps, cracks and holes. On a cold day feel the internal plaster wall or window frame and if it’s cold too you’ll know.

Fill inside and outside gaps around the window frame with silicone. If the gaps are big enough use an expanding foam filler aerosol.

Finally turn up the home heating to between 18 and 20 degrees. Dry air is far cheaper to heat than wet air so by drying the internal air you’ll ultimately make a saving.

Insulate the windows:

10% to 30% of a rooms heat can escape through a closed window. In the opposite way to a central heating radiator a cold glass surface takes the warmth from the room.

You have to decide how bad the condensation is and if it’s worth reducing the ventilation to the window by covering it to save on heat loss?

A sure way to reduce the condensation would be to increase the air moving over it using a small fan but this will also lose significantly more heat from the room.

There are 4 further options to help significantly improve our double glazing for both heat saving and reduce condensation.

Cheap option:

Plastic film applied to the window frame, and shrunk to fit. Applied seasonally it is cheap at around €50 to cover the entire home and when applied correctly its barely visible, has a slightly grey tint, but highly effective. It’s not much use for the aluminium patio doors which get extremely cold and the adhesive tends to fail too easily. If the sheet ripples afterwards either the tape has too much glue, so don't buy that brand again, or the surface hasn’t been cleaned sufficiently.

Suppliers on Amazon

Slightly More:

Plastic film applied directly to the glass, normally associated with office buildings and can have a tint or mirror affect. More expensive but they lasts several years and would match the cling film type over the same period and both reduce heat loss and reduce condensation.

One of many Film Suppliers

Much more:

Change the window glass units within the existing frames. Modern glass coatings and seals are significantly better at reducing heat loss and are made to measure so can be swapped by a professional.

Most Expensive:

Change the entire window and the insulation qualities of the window glass, frame and insulation around the entire window can be done properly.

3. Increase Ventilation

The difficulty is to balance between keeping warm and letting colder fresh dry air in.

Window, free.

The most obvious is to leave the windows open but it’s a security risk, a safety risk for small children, and it also gets a huge cold draught through the house.

Vents in the home, free.

All rooms have breather vents up high in the wall but have you checked inside them since some don’t actually have a hole through to the outside, ours were full of rubble, blocked up with cement and most didn’t have a plastic sleeve pipe and were therefore ruining the wall insulation by letting cold air get into the cavity.

You can change the interior vent cover to one that can be opened and closed to prevent cold draughts on days when the wind is blowing hard, just remember to open them again later. The version in the image opposite prevents draughts by its design.

Suppliers on Amazon

Your chimney

If you light a fire it forces hot air up and out and this action pulls in fresh air through your wall vents.

Internal doors, free.

Leave internal doors open at night to increase the air flow around the home. However this is a contradiction if you have security concerns, fire and smoke risks, or simply have a noisy sleeper in the house.

Window vents, €5 each.

These are installed within the window frame and not in the glass. Most modern double glazing windows have these but you can install them quite easily and they serve the same purpose as the wall vents.

Suppliers on Amazon

Extractor fans, €20 to € 150 each.

Typically these are fitted in the bathrooms and possibly above your cooker hob. They are not very effective unless you’ve invested money and installed a powerful version. They need to run for quite some time to be effective since shower room walls are still wet even when the steam has cleared.

There are expensive heat recovery versions too but the main aim is to expel wet air and force fresh air into the house through any air gaps around your home.

Suppliers on Amazon

Positive Input Pressure, €300 to €350.

Since we don’t have a tropical, humid climate the air outside is typically much drier than the air inside your home throughout the entire year. Don’t mix up the idea of rain and humidity since often when the rain stops the wind dries it off the windows fairly quickly.

A PIP device is one you install in the attic to draw air into your home and continuously blow it slowly through a ceiling vent typically installed in the landing area.

Taking filtered air from the attic means it’s warmer and drier than outside and the fan blows extremely slowly to not cause a cold draught. An optional extra pulse heater will slightly warm the incoming air if the attic air is freezing cold.

The overall effect is that those wall vents in every room are now always expelling wet, used air. It also doesn’t really matter if you close all the doors in the house since they’re not air tight seals. The dry fresh air will find its way to mix with all rooms of a traditional style house and you’re less likely to get any incoming draughts.

Potential Supplier

The end result is worth all the effort.

It can take several weeks to ‘dry out’ the fabric of a house using any of the measures mentioned and now is the time to be doing it. All the ventilation and drying your house has undergone through the summer can be undone within a matter of days.

If you need help or simply want a professionals opinion then there are several local trades to consult.

These have provided previous articles and are recommended.