4th September 2017

How to Install a Window Architrave

Watch our video demonstration on installing a window architrave, and print out our instructions below to help with your own window installation.

Tools required

  • Combination square or marking gauge
  • Sharp pencil
  • Mitre saw
  • Nail gun or hammer and punch
  • PVA adhesive
  • Damp cloth
  • Ear muffs or plugs
  1. Mark the quirk or step (distance between inside edge of window reveal and inside edge of the architrave, normally 5mm, but may vary depending on client requirements) on all corners as well as at intervals between corners. These points are used for measuring the short lengths of architrave as well as a guide for positioning inside edge of architrave when nailing in place.
  2. Measure the distance between corner quirk points which represents the short length of your 45 degree mitre cuts. We are installing the right side architrave first and then working around the window in an anticlockwise direction.
  3. Cut a 45 degree mitre cut on both ends of a piece of architrave and add 5mm to the distance measured on step 2.
  4. Position the architrave so the bottom 45 degree mitre cut is held in relation to the bottom quirk intersection point and then remark the top intersection quirk point.
  5. Trim the top 45 degree mitre cut so it meets the top quirk intersection point exactly and nail in position. Nail into window reveal first, keeping inside edge of architrave parallel with quirk points and then nail to plaster and timber framework behind.
  6. Repeat step 2 and 3.
  7. Position right end top 45 degree mitre cut in position, keeping it in line with the quirk points and maintaining the inside edge parallel with the top window reveal. Press top right mitre cut down firmly against the side top mitre cut and observe how neat the fit is. If there is a slight gap on inside or outside of the 45 degree mitre cut, then re adjust the mitre saw and recut to make the mitre joint a neat fit.
  8. Position the right end of the top architrave neatly against the side architrave that is already fixed in place and then mark the left quirk intersection point and trim to length.
  9. Apply PVA glue on the right end of top architrave and position and nail in place as per Step 5.
  10. Wipe off excess glue from corner mitre joint with a damp cloth.
  11. Repeat steps 6 to 10 with the last two pieces of architrave.

Great Work! Your job is now ready to sand and paint.

If you have any questions or want some advice, don’t hesitate to contact our friendly team for help.

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