???? How to Measure Aluminium Sliding Windows for Installation – A Step-by-Step Guide
Accurate measurement is critical when ordering aluminium sliding windows to ensure a perfect fit, avoid delays, and prevent costly modifications during installation. Whether you’re replacing old windows or fitting new ones, knowing how to measure properly will save you time and money.
This guide walks you through the correct process to measure aluminium sliding windows for installation.
????️ Tools You’ll Need
Tape measure (metal recommended)
Notepad and pen
Ladder (if measuring higher windows)
Level (optional)
Assistant (optional for large windows)
???? Step 1: Measure the Window Opening
Width Measurement
Measure the width of the window opening from the inside edge of the left frame to the inside edge of the right frame.
Take measurements at the top, middle, and bottom of the opening.
Use the smallest measurement as the width.
Height Measurement
Measure the height from the inside edge of the sill (bottom) to the inside edge of the top frame.
Take measurements at the left, center, and right.
Use the smallest measurement as the height.
???? Step 2: Measure the Window Depth
Measure the thickness of the wall where the window will be installed.
This will help determine the correct frame depth needed for a flush fit.
???? Step 3: Check for Squareness
Use a level or measure diagonally from corner to corner.
If the two diagonal measurements differ by more than 5 mm, the opening is not square and may require adjustments or custom frames.
???? Step 4: Note Additional Details
Check for obstructions like handles, grilles, or mouldings.
Measure any existing trims or stops that may affect fitting.
Note the type of window sill or reveal depth.
???? Step 5: Account for Installation Allowance
Leave a clearance gap of about 5–10 mm around the window frame for fitting and insulation foam.
Your installer will fill this gap with appropriate sealant or foam to ensure airtightness.
???? Tips for Accurate Measurement
Always measure twice to avoid errors.
Use a rigid tape measure for accuracy.
Record all measurements clearly.
Consult your supplier or installer if unsure about any dimension.
???? Final Thoughts
Correct measurements are the foundation of a successful aluminium sliding window installation. Taking your time to measure carefully will ensure your windows fit perfectly, operate smoothly, and provide the best performance.