Part 8.2 Windows and external glazed doors
New for 2022
This Part does not cover the installation of assemblies that are internal or revolving doors, fixed louvres, skylights, rooflights and windows not installed in the vertical plane, windows in greenhouses or horticultural buildings or frameless sliding doors.
Installation of windows
New for 2022
Windows must be installed in accordance with the following:
- Structural building loads must not be transferred to the window assembly.
- A minimum 10 mm gap must be provided between the top of the window assembly and any loadbearing framing or masonry wall element.
- The requirements of (b) may be increased where necessary to allow for frame settlement over wide openings.
- Packing, if provided between each window assembly and the frame, must be—
It is important for windows to be fixed correctly in the external frame or wall of a building to prevent buckling, diagonal distortion or twisting that may compromise weathertightness around the perimeter of the opening. Correct installation is also critical to ensure windows resist design wind pressures that the external walls of the building are subject to over its expected life and transfer the resultant forces only to the framing members beside the window. Consideration should be given to any additional details for systems designed specifically to meet acoustic or energy efficiency requirements.
Window assemblies should be installed so they are as close as possible to being perpendicular with the vertical and horizontal planes and where all corners form right-angles, have equal distances when measured diagonally to ensure they are square.
A gap provided between the top of the assembly and the external wall frame will allow for settlement after construction and prevent the transfer of structural loads. Where packing is used between the openings in the external wall and the window assembly, it should be of a material that is compatible with both the frame and the window assembly. It should also be positioned and fixed to stay in place permanently and ensure the sides and sills remain straight.
Where aluminium sills of a window assembly may contact masonry, particularly mortar, an isolating material such as bituminous membranes or paints and caulking compounds containing zinc chromates should be used. Care must be taken to minimise any gaps between sills and external skins to prevent excessive ingress of water.