Bisaillon Patio Doors October 03rd, 2017 - 04:40:31
Patio doors comprise an outer frame plus individual door frames. These can be made from wood (soft- and/or hard-wood), metal or alloys (usually aluminium), pvc (polyvinyl chloride, a thermo-plastic polymer - the u stands for unplasticised) or a composite material, which may comprise any of the foregoing materials plus grp (glass reinforced polymer). There is also a style known as frameless, where the vertical sides of each door have no frames.
A visible "kitemark" on the glass is the consumers assurance that the double-glazed unit has been manufactured to British standards. The BSI has numerous standards, including: U-value verification, Window Energy Rating and Window Installation. The lower the U-value, the better the thermal performance and most local authorities will require this to be 1.8 or better to meet building regulations.
Sight lines is the term used to describe the interruptions in the view through the doors; in other words, the width of the vertical opaque areas between the glass when the doors are closed. On hinged doors, such as French doors and bi folding doors, timber and pvc frames generally have broad sight lines because, unlike aluminium, narrower frames would not be strong enough to be fit for purpose. As a guide to the width of two frames together, cheaper pvc door frames can exceed 200mm, aluminium frames are typically between 135mm and 160mm and frameless patio doors sight lines are under 40mm. Depending on the width of each door and number of doors to be installed, the difference in glass to frame ratio could be significant.
Arguably, French doors could be considered as retractable as each door can be pulled back. The advantage of retractable doors is that maximum access is possible between the two sides of the aperture whereas sliding panel doors generally overlap unless built to retract into a recess.