Installing windows can be tricky, but there’s plenty you can do to make it easier.
Modern windows are often big, heavy and sometimes awkward shapes. The increasing use of insulated glazing units and a fondness for large doors that slide or fold away has added significantly to the weight that needs to be lifted, handled and manoeuvred.
There is plenty that can be done on site to make window installation less fraught and lower the potential for damage to both the window and the installer. By following some key steps, your windows should go in smoothly.
Openings and framing
Site measure all openings for width (top, bottom and middle) and height (left, right and middle) before fabrication of the windows.
Check the trimming framing for accuracy, and adjust the installation of the cladding to ensure that window flange cover will be maintained. Where the ends of the cladding are cut to the line of the trimming stud, cover may be lost if the trimming stud is out of plumb.
Construct wall frames correctly. It is common practice for pre-nailed frames to arrive on site with the sill trimmer bevelled on the front edge, but for cavity construction, the bevel is not required and may make the installation of the window support brackets and the window more difficult.
Preparing the opening
Prepare the opening correctly. Ensure sufficient allowance has been made for the build-up in materials that occurs at corners (for example, the layers of flexible flashing tape) and to allow for installation of the packers and air seal.
Trim off the wall underlay that is turned into the framed opening at the internal face of the framing or turn it down or along the inside face of the framing and staple it (see Figure 1). Don’t cut it off part way across the sill trimmer or trimming stud as this makes achieving an effective air seal much harder.
Checking, stacking and storage
Check windows on delivery to ensure they are ‘well made’, are the correct size and have the correct glass. Windows have been supplied to sites without the reveals being fixed to the aluminium frame – the staples were missing.
Provide a clear, dry, level storage space with unobstructed access. Stack windows in accordance with manufacturer’s instructions – where stacked on edge, ensure they are restrained to prevent them falling over.
Clear access for installation
Ensure the site is tidy – the biggest hindrance to window installation is not having clear access to the framed opening to allow the window to be safely carried to its position and lifted into place.
Don’t try to be a hero
Above all, don’t struggle with a larger window by yourself – get some help. A jarred or dropped window may be damaged, and there is the possibility of injury to you or someone else.
For heavier windows, site glazing may be required after the frame is installed.
Fixing and support
Complete the fixing in of the window as installation proceeds. Don’t tack it in place – you might forget to come back later and fix it in properly.
Install packers at each window fixing point. Not doing this may lead to poor performance.
For larger windows in higher wind areas, ensure the fixing of the window into the trimmed opening is sufficient for the wind loads. For specific design wind zones, the fixing may require input from an engineer.
Provide sill support and ensure the sill trimmers are securely fixed in place. The potential for rotation of a poorly secured sill trimmer is greater where windows are larger, double glazed (heavier) or projected forward of the framing line where a cavity is installed behind the cladding.
Articles are correct at the time of publication but may have since become outdated.