If you've noticed a foggy or hazy appearance between the two panes of your double glazed windows, you're dealing with a failed sealed unit. It's one of the most common UPVC window complaints — and it has a definitive cause and solution.
Why Does Misting Happen?
A double-glazed sealed unit is hermetically sealed — the space between the two panes is filled with dry air or an inert gas like argon, and the unit is sealed around the edges with a desiccant and a primary sealant. Over time, the edge seal can break down due to thermal cycling (the expansion and contraction of the glass as temperatures change), poor original installation, or simply old age. When the seal fails, moisture-laden air enters the cavity. The glass surfaces inside become contaminated and the misting cannot be removed without replacing the unit.
Can a Misted Unit Be Fixed Without Replacement?
Various companies offer to 'clear' misted units by drilling into the glass, injecting a cleaning solution, and inserting a valve. While this can temporarily improve appearance, it does not restore the thermal performance of the unit and the improvement is often short-lived. For a permanent solution, the only option is to replace the sealed unit.
What Does Sealed Unit Replacement Involve?
Replacing a sealed unit is a professional job involving removing the glazing beads, extracting the old unit, measuring, ordering a replacement unit to the correct size and specification, and fitting and re-beading. The glass unit itself accounts for most of the cost — the frame can usually be reused. The Glass Guardian supplies A-rated sealed units as standard for all glass replacement work.
Need a UPVC Repair in Birmingham or the Black Country?
The Glass Guardian provides fast, affordable UPVC window and door repairs across Birmingham, Dudley, Walsall, Wolverhampton, and the surrounding area. Call for a free quote.