Cat Flap Fitter Advice.
Misted Window, When Installing a Cat flap Can Save You Money
Cat out of glass
It is moisture getting into the glass and cannot escape. Usually, this is caused by the British weather. You will discover double glazed windows that are more exposed to the elements at your property fail quicker.
In autumn and spring when air gets in between the two pieces of glass they will expand in the cold then when there is a sudden change of temperature, like a warm spring morning, the stress will break the double glazed unit seal and water or moisture condensing on the glass becomes visible.
Often I hear stories from customers that a double glazing salesman has informed them that a whole new frame is required. This is nonsense UPVC, wood or aluminium frames are designed so that the glass can be replaced easily.