Measuring Guide
Bifold Door Measuring Guide
Measuring correctly is essential when ordering your new bifold doors. The width and height you order should always be based on the structural opening size minus fitting tolerances.
Step 1: Measure the structural opening
Measure the full brick-to-brick or plaster-to-plaster opening where the doors will sit.
Take:
- Three width measurements (top, middle and bottom)
- Three height measurements (left, centre and right)
Always use the smallest measurement from each dimension.
Step 2: Check the opening is square
Use a large spirit level to ensure the sides are plumb and the head is level.
Measure diagonally from corner to corner across the opening:
- If both diagonal measurements are equal, the opening is square
- If not, always work from the smallest measurements
Step 3: Allow fitting tolerance
A fitting tolerance must be allowed so the frame can be installed square and level.
We recommend allowing:
10–15mm tolerance
between the structural opening and the manufacturing size.
This provides space for:
- Packers
- Adjustment
- Smooth installation
Step 4: Calculate the size to order
Take the smallest width and height measurements and subtract 10–15mm from each.
Example:
Structural opening: 3015mm x 2115mm
Recommended order size: 3000mm x 2100mm
Important when ordering
When ordering bifold doors, the overall size must include all components such as:
- Cills
- Add-ons
- Head extensions
- Any additional frame extensions