Calculating Door Frame Opening Width

Introduction

• Determining the appropriate width for a door frame opening is essential in construction.
• The opening must accommodate the door, jamb, and allow space for adjustments or packing.

Key Considerations for Frame Opening

1. Door Width

   • Standard door widths include 820mm, 770mm, 720mm, 670mm, and 620mm.
   • Modern options offer a range of custom widths.

2. Jamb Thickness

   • Must consider the thickness of the jamb material.
   • Example thicknesses: 15mm, 18mm, 19mm.
   • Focus on the narrower piece of jamb material.

3. Clearance Allowance

   • Necessary clearance between the door and jamb.
   • Typical clearance: 3mm for painted finishes.
   • Clearance can be reduced to 2mm for stained or clear finishes.

4. Packing Space

   • Allows for adjustment if studs are not perfectly plumb.
   • Standard packing allowance: 10mm on each side.

5. Repetition of Dimensions

   • All measurements and allowances must be mirrored on both sides of the door.

Calculating Total Opening Width

• Add all allowances and repetitions to calculate the required opening width.
• Example Calculation:
  • Door width: 820mm
  • Jamb thickness: 15mm each side
  • Clearance: 3mm each side
  • Packing: 10mm each side
  • Total calculated opening: 876mm
  • Recommended adjustment to 880mm for added packing flexibility.

Conclusion

• Always ensure measurements are accurate to prevent fitting issues.
• Adjust opening width to accommodate any deviations in construction.

Additional Information

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