Autumn view through window

Seasonal update | Our guide to the weather changing

As the nights draw in and the weather starts to cool down our after-sales team get the occasional phone call from customers asking about changes to their doors and windows. To offer advice and provide more information we have put together this blog with some explanations and further detail.

External Condensation

With highly insulated products and glazing, external condensation can naturally occur demonstrating that the glass is doing its job keeping the heat inside making the external pane of glass cool and susceptible to external condensation.  This is perfectly normal and is not showing any failure of the glass, the external condensation may show markings on the glass such as sucker marks left during the manufacture or installation process which again do not constitute a failure of the product.  The marks in time will fade or disappear through regular cleaning and sunshine.

Moisture condenses out of the air onto a cold surface that is said to be below the dew point. The dew point varies with the air temperature and the amount of moisture it contains. Particularly in spring and autumn, the glass temperature can fall to a low level during the night and the dew point can be comparatively high in these seasons. The glass temperature can be below the dew point under these conditions and moisture can condense onto the surface.

In order to save energy, maintain a comfortable internal environment and satisfy building regulations requirements, the windows we fit in our homes are much more thermally efficient than in the past. With single glazing and older style double glazing, a large proportion of heat was lost to the outside through the glass. With modern low emissivity glass, more of the heat is kept inside and the outer pane is not heated as much.

The more thermally insulating the glass is, the lower the outer pane temperature is likely to be and the greater the risk of condensation on the external surface. In northern European countries, where levels of thermal insulation are higher than in the UK, the phenomenon is understood and accepted.

There is not much that can be done to avoid the risk of condensation to the outside. In many cases, the condensation does not last long. A little heat from the sun warms the outer glass enough to evaporate the moisture and a gentle breeze or wind will help.

You may notice that not all of the panes are affected by early morning condensation, even in the same window. Subtle differences in orientation and the position of objects outside the window can change the surface temperature of the glass to the point that one pane suffers and another does not. Any object such as a canopy or tree blocking off the window to a clear night sky will also reduce the effect.

The plus point is the knowledge that your windows are keeping the heat in as they are designed to, proving that you have a superior insulating glass product.

Internal Condensation

As the weather cools you may notice that some condensation can appear on the aluminium frames, this is quite normal and there are many factors that can cause this and is not a failure of the product.

Whilst our modern aluminum profiles have a thermal break separating the cold external aluminum frame from the warmer inside an amount of heat transfer will naturally occur.  Despite the advanced performance of the doors there is every chance that, because the frames are made of metal, they may be one of the coolest surfaces in your home – which can lead to moisture in the air condensing at this point causing condensation.

With the change to autumn and winter the problem is exacerbated when the outside temperature is much lower and ventilation within the home is reduced due to closed windows and doors. This creates the perfect conditions for condensation as firstly the air is warm because it is heated, secondly the moisture we create through bathing, cooking, washing and even breathing is trapped in our homes and finally, exterior facing surfaces such as windows are much cooler.

What can be done to reduce or prevent condensation? Ventilation is the key to reducing the amount of water in the air which in turn will reduce the chance of condensation, this may be through opening windows during and after cooking, drying washing or bathing or through the use of mechanical ventilation with extractor fans or a dehumidifier.

Visible Water in Drainage Channels

All of our products are laboratory tested to withstand both water and air ingress although on occasion you may see some water within the drainage locations.  Both windows and sliding doors are designed with drainage slots concealed within the frames that will transfer water to the outside should it gain entry through the first external seal.  During periods of heavy or consistent rain, you may notice that some water is visible in either the bottom frame of a window when you open it or within the bottom track of your sliding door.

This is perfectly normal and the water will escape.  Due to the nature of a sliding door system, the panels are staggered across multiple tracks, and each of the tracks contains drainage chambers which will allow the water to escape.  Below the points where the panels alternate to a different track there is a sealing block to reduce the amount of water that can pass, this seal can become overwhelmed during downpours or consistent rain causing some water to become visible on the internal section of the drainage channel.  This is perfectly normal and the water will eventually work its way to the outside.

When should you contact us? The most common problem is that the drainage holes have become blocked, this generally happens when the doors are new and have been installed on an active building site.  Dust and debris from various trades can find its way into the drainage channels causing problems.  You will see the slots cut into the tracks of the sliding doors, you should check they are free of debris and remove anything that may be causing the blockages.  Should you ever experience water totally overwhelming a system and ending up on your floor inside this may indicate there is a problem.  Our aftersales department will be able to offer advice and organize a team to visit should it be required.