How to Trim Out a Window

By: Scott Gibson, This Old House magazine

Shopping List

Supplies You Will Need

1. WOOD MOLDING

2. CARPENTER'S GLUE

3. PENCIL

4. PAINT OR STAIN

5. 120-GRIT SANDPAPER

6. WOOD PUTTY

7. 4D AND 8D FINISHING NAILS

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Tools List
Tools You Will Need
- 20-ounce finish hammer
- Hand plane,
  for trimming jamb extensions
- Measuring tape
- Router,
  for making stool profile
- Random-orbit sander,
  or hand sanding block
- Jigsaw,
  for notching stool and profiling apron
- Pneumatic nailer,
  for attaching casing
- Compass,
  for transferring marks and reveal lines
- Table saw,
  for cutting rabbet in bottom of stool
- Square,
  for marking casing, stool, and apron
- Utility knife or chisel,
  for trimming drywall and adjusting fit of stool
- Miter saw,
  for crosscutting trim pieces to length
- Nail set (to recess heads of hand-driven nails
- Drill with 1/16-inch-diameter bit,
  for making pilot holes before hand nailing
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Product selections for this project
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Photos: David Carmack

Introduction
Overview
Steps:
- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9

1. Prep the jambs

Hold a straightedge across the window; check that each jamb is flush with the wall. If they protrude, plane them down to the wall. If the jambs fall short of the wall, measure the largest gap between the straightedge and each jamb. Then, from 1x stock, rip jamb extensions as wide as necessary and ¼inch thinner than the jamb thickness. Holding the strip against the jamb, drive 1 ½inch 18-gauge pneumatic nails (or 4d finish nails) every 8 to 10 inches. Plane off any excess.

Spread the legs of a compass ¼ inch and rest the point on one of the jamb's lower inside corners. Using the inside face of the jamb as a guide, draw a reveal line along the edges of all three jambs.

Tip: For a tight fit between the casing and jamb, plane a slight bevel into the wall-side edge of the jamb.