Condensation: Venting your frustration

Dampness is something many people associate (rather unfairly) with Manchester, where our EKA North office is located. I say unfairly as Manchester isn’t actually the wettest City in the UK – it’s not even in the top 10. Anyway, dampness was on my mind so I recently reviewed all the damp/water ingress investigations and reports that I’ve written over the past few years, curious to discover what percentage of these related to a certain type of damp issue e.g. condensation or poor maintenance of building elements.

Over 65% of these investigations pointed to condensation as the cause, based on my deduction at the time of investigation.

And around 40% had an issue relating to poor maintenance of rainwater goods and/or roof coverings. On discovering this, I thought of the time, money and inconvenience that could be alleviated if homeowners were armed with the appropriate knowledge about the causes of water ingress – particularly condensation.

And here, I am hoping to share enough in a brief blog to ensure that people with a responsibility to look after a property – be they a leaseholder, freeholder or a property manager – have some clear starting points in ascertaining the cause of the damp.

The first step – as where most of my “water ingress” inspections took place – is to look at internal living conditions and thus either eliminate or diagnose condensation. So, what is condensation?

Condensation is water in the air existing as vapour, i.e. water in its gaseous form. Condensation actually arises when the vapour comes into contact with a cold surface (a surface that is at or below the dew point temperature of the room) and cools to the point it becomes a liquid.

This is why it becomes an issue on our windows, external walls and even fixtures and fittings that have a cool surface such as metals. In a well ventilated and insulated property, water vapour still exists and there may be minor signs of condensation, such as water droplets on the internal glazing of the window, but more often than not, it quickly disperses. Trickle vents installed in double or triple glazed windows help to dissipate condensation (hint: always leave them open in the winter months!).

There is more than one type of condensation. BS 5250: Code of practice for control of condensation in buildings, gives four different types:

• Surface condensation – this is the most commonly found.
• Interstitial condensation – occurs within or between the layers of the building, such as the underside to a cold deck roof.
• Reverse condensation – a form of interstitial and occurs to southern facing walls that get sunlight after a wet period.
• Radiation condensation – another form of interstitial, which occurs when there is rapid heat loss by radiation on a clear, cold night.

So how do you know if your damp issue is condensation related? A surveyor will have a multitude of tools at his/her disposal: moisture meters, hygrometers and even salt testing kits.

Condensation is pure water so if no salts are detected then most likely, but not definitively, the problem can be related to condensation, hence the kits can be very useful.

Mould is often an indication of condensation but a lack of mould does not rule out condensation and visa-versa. So, assuming you don’t have moisture meters or salt testing kits lying around at home, then the following steps may help you diagnose condensation – they are good tips to prevent condensation in any case:

1. Avoid drying your washing indoors. If you have no option, then dry them in a room with an open window and close the door to the rest of your home.
2. When bathing or cooking ensure all doors are closed to other parts of your home, open a window and turn on extractor fans – clean the fans as well, make sure they are in working order. Upgrading the fan if it is old may be worth considering.
3. In bedrooms, make sure trickle vents are in working order and leave them open when sleeping. We can exhale up to 500ml of water during the night – that’s nearly a pint’s worth!
4. Maintain adequate working and opening windows. If a window is stuck closed, call out a window specialist to ease and repair.
5. Provide a constant general level of heat to your home in the colder months. Low to mid heat levels are ample when no one is home. This can then can be increased in the evening avoiding sudden bursts of heat, though this does rely on having a thermostatically controlled heating system. The aim here is to ensure the air and building fabric temperature are elevated during times of colder weather.

Warm air holds more moisture than cold air. When warm air is cooled, such as when the heating is switched off at night, it will deposit the water that it can no longer retain as condensation on a cold surface.

Condensation is more of an issue in the colder months of the year and so there is a “condensation season” which is typically from September – March, though this is changing as we are seeing higher temperatures in September.

If you have a damp problem then the above steps 1-5 should be undertaken during the colder months which may confirm condensation is the problem or help to eliminate it. These simple steps provide practical and immediate steps to your damp diagnosis. If not condensation, what else could it be?

Other common damp / water ingress issues 

Penetrating damp
Is water – not necessarily rain – entering your building from outside the habitable space? External sources of water include precipitation (rain, snow, sleet, hail and even fog) and external plumbing leaks such as those from soil pipes and any water entering the building above the DPC (damp proof course) level.

I have found that penetrating dampness generally falls down to poor maintenance. Typical examples are overflowing hopper heads, broken gutters or faulty downpipes. But damp penetration can be due to poor design, such as cistern overflows dripping for a long period of time eroding the pointing and penetrating the wall. These overflows should be designed so that water is directed away from the building fabric via downpipes.

Cavity walls were designed to assist in the prevention of penetrating damp to solid walls. A well-designed, constructed and maintained cavity wall will do just that.

Penetrating dampness will manifest itself in some way, usually by internal or external staining. Check for staining down the brickwork and follow the stain upwards; it will likely lead to the source. A regular cycle of rain water goods cleaning/clearing out is always recommended. Doing this twice a year, whilst it may cost a few hundred pounds, could savemoney and perhaps more importantly, save time and avoid severe inconvenience and expensive insurance claims.

A surveyor will have tools such as infrared cameras and may recommend water tests to determine the source of water i.e. waste, foul or tap. Again salt tests can be used to determine the source.

Internal plumbing leaks
These are not so easy to self-diagnose. If you are on a water meter then higher bills will be an indication of escaping water, but due to the potential of causing further damage by self-diagnosing and investigating, we would recommend always seeking professional advice if you believe that there is an internal plumbing leak. Insurance policies often cover ‘trace and access’ so you can rest assured the leak will be found by the insurer’s contractor and isolated.

Detecting water leaks
The subject of a future blog, we will explore the leak detection systems available to property developers/house builders and managing agents. These systems very cleverly detect, raise the alarm and even and shut off a supply to prevent large-scale escape of water damage.

If you have a tricky damp issue that needs diagnosis, please get in touch with a member of the EKA team here in Manchester, or the slightly drier teams in London or Brighton.

Andrew Banister MRICS is Regional Director North, at Earl Kendrick Associates 0161 804 8439 andrew.banister@earlkendrick.com