One of the most common issues we see when we go out to quote for replacement windows and doors is usually condensation on the glass, frames and surrounding area.
Sometimes due to a lot of moisture, the reveals touching off the face of the windows may have turned black and have mould on them.
Moisture forms when hot air meets cold air and usually forms on the coldest surface in the room i.e. the window.
There are many variables at work here, as follows:
- No attic insulation or not enough of it, which allows the cold air from the attic to come down and meet the warm air in the room. Standard building practice for years was to put 6” of Fibreglass insulation in between the rafters and a foilback slab onto the ceiling of the room below. It has since been proven that cold will transfer through a timber joist and into the room below. The current building regulation recommends 12” of Fibreglass in an attic, 6” in between the joist & 6” running across the top of the jois. Also an insulated slab below, would be a huge benefit.
- Drying clothes on radiators. As the clothes dry, there is a higher moisture content in the air than normal and when this hits the cold glass area, condensation occurs.
- Aluminium or Steel window frames which don't have any real thermal resistance. These frames are always cold to the touch and can be one of the biggest causes of condensation in this country. Most of the time, these windows also tend to be single-glazed. Once the temperature drops outside and the pane of glass gets cold, condensation appears.
- Older Double Glazed units. These would be units which may have been manufactured before energy efficiency became common practice. Older double glazed units won’t have low E glass, no argon gas filled cavities, & will only have an aluminium spacer which separates the 2 panes of glass. Nowadays, all double or triple glazed units use a foam spacer bar because the aluminium bar has been proven to be a cold bridge which allowed the cold to pass though and create a cold patch on the inside pane and create a strip of moisture across the bottom or sides. All recent units also incorporate a pane of Low-E glass on the inside which helps keep the heat inside the room & make the windows more “Energy efficient”.
- If you have just re-plastered a room or replaced windows, sometimes there can be a small amount of condensation while the plaster dries out.
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