How have I got condensation inside my double glazed unit?
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The double glazed unit consists of 2 pieces of glass held apart around the edge by a (usually silver colored) spacer bar. This bar is filled with a desiccant, tiny silica balls similar to those found in parcels to reduce the moisture levels. In the case of double glazed units, the silica soaks up any residual moisture held in the space within the unit when it is first made. Around the outside of this metal spacer bar, sealant is pumped to seal the unit and complete the process.
After a period of time the seal 'breaks down', causing a hairline fracture in the seal, thereby letting air containing moisture in. Various factors can accelerate this breakdown, such as wood frames and putty, poor frame drainage, poor installations not leaving sufficient gap between the glass edge and the frame, locations in extreme sunny positions or where excessive vibrations occur.
Once air can get into the unit, the silica originally used becomes fully saturated and condensation starts to form as temperatures rise and fall against the side of the glass.
If your units were installed during the last 10 years, check your guarantee and see if you are still covered.
Despite rumours to the contrary, it is not possible to repair the units by splitting them and re-sealing them!
Stuart
