FAQ: The abbreviation FENSA stands for FENESTRATION - SELF ASSESSMENT.
The uk dictionary definition of the word fenestral or fenestrate is " belonging to or like a window" The word fenestration is "the arrangement of windows in a building". FENSA is used by double glazing uk trade companies to certify that their replacement windows and doors installed comply with Building Regulations Document L (and more), actually checking av. 1% of all replacement windows installations.
Did You Know?
Double glazing sealed units misting up and going misty inside the glass.
About the premature failure "misting up" of double glazed sealed Units:
Once you have 'misty' double glazed sealed units:
In the trade we say that the double glazed sealed unit has 'broken down'. This means that the perimeter edge seal has lost it's integrity and that it is letting in moisture somewhere. The moisture itself is hard to spot at first, sometimes becoming only visible as the Sun or another heat source 'draws' the moisture up. Typically the moisture will be drawn in as the atmospheric pressure changes, and it will build up eventually condensing into water inside the sealed unit. This can sometimes look like a fish tank with several inches of water inside that cannot escape, and quite funny when it is in a door and the water sloshes about!
What you can do about misted up double glazed sealed units:
The only answer is to replace the double glazed sealed unit with new ones. That almost always means little or no alteration or disruption to the framework if it is sound as the glass sealed unit is designed to be removable and replaceable. Trying to separate the glass is not practical as the sealed unit is factory made with the glass bonded together to (hopefully) last a lifetime.
Why did the double glazed sealed unit break down:
There are a number of different glazing techniques for the fitting of double glazing sealed units into different frame materials like Wood, as opposed to either PVC-U or Aluminium frames, and there are some important Do's and Don'ts to ensure a reasonable life expectancy for the sealed unit.
Although there many reasons why a double glazed sealed unit may mist up inside when it has 'broken down' due to premature failure of the perimeter seal, the cause will either be down to how the sealed unit was made, how the framework it is fitted into was made, or how the double glazed sealed unit was fitted into the framework. On top of this environment conditions may play a part, such as wind or sonic loads, and possible exposure of the perimeter seal to aggressive chemicals such as those found in washing up liquid. This may all sound a bit complicated, but the cause of a premature failure of a double glazed sealed unit can usually be fairly easily traced once the sealed unit has been removed from it's frame.
Choose he frame material below to find out more specific causes of sealed unit failure:
Read up more about sealed units: