Instructions for Building Wood Sash Windows

Written by brian scudder
  • Share
  • Tweet
  • Share
  • Pin
  • Email
Instructions for Building Wood Sash Windows
Wood sash windows add a decorative touch (window with flowerpot image by Stanislav Pepeliaev from

Building wood sash windows adds an elegant feature to homes, incorporating a decorative, yet functional moulding and edge profile to the window sash. Building wood sash windows requires the use of router bit kit specifically designed for building wood window sashes. These kits consist of two separate router bits, one to cut the interior side of the sash and the other cuts the exterior. The interior sash bit is used to cut the Roman Ogee profile and also serves to cut the locking joints in the corner of the sash. The exterior sash bit cuts the opposite profile of the interior bit, while simultaneously cutting the rebate for the glass to set in.

Skill level:

Things you need

  • Tape measure
  • Mitre saw
  • Sash router bit set
  • Router
  • Router table
  • 6 pieces poplar wood 1 1/4-by-3-by-36 inches long
  • 1 piece 1 1/4-by-5-by-36 inch poplar
  • Table saw
  • Wood glue
  • 4-penny finish nails
  • Hammer
  • Nail set
  • 2 48-inch bar clamps
  • Glazing points
  • Glazing compound

Show MoreHide


  1. 1

    Determine the size of the sash according to the window frame opening.

  2. 2

    Transfer the dimensions onto four of the 3-inch poplar pieces. These pieces are for the perimeter frame of the sash.

  3. 3

    Mark the dimensions on the vertical pieces first. The vertical pieces of the sash are called the "stiles," while the horizontal pieces are known as "rails."

  4. 4

    Mark the rails to the predetermined dimension and subtract 5 1/4-inches for the lap onto the stile pieces. The lap length refers to the amount in which the rail extends into the stile on each side. The subtracted length is due to the thickness of the right and left side which are 3 inches each. The rails will extend into each side 3/8 inches.

  5. 5

    Transfer the length dimension of the sash onto one of the remaining 3-inch wide boards and subtract 5 1/4-inches. This piece will be used for the vertical mullion pieces.

  6. 6

    Mark the remaining 3-inch piece to the same length as the previously calculated rail length.

  7. 7

    Cut the six pieces on the marks by placing them on the mitre saw table and tight against the fence.

  8. 8

    Set the saw to 90 degrees by unlocking the table lock located on the front of the saw and swing the saw until the angle indicator aligns with 90 degrees on the angle scale.

  9. 9

    Place the end cope bit into the router and tighten it.

  10. 10

    Adjust the height of the end cope bit by raising the router until the top of the guide bearing is 1 1/4-inch from the surface of the router table.

  11. 11

    Align the router table fence flush with the guide bearing of the end cope bit.

  12. 12

    Lay the rail piece on the router table with the end tight against the fence and cut the ends of both rails.

  13. 13

    Place the 5-inch piece against the rip fence and cut the entire length of it with the end cope bit. This piece will be used as a jig for securing the smaller mullion pieces as they are machined.

  14. 14

    Place two of the 3-inch poplar mullion pieces on the router table and make end cuts on both of them.

  15. 15

    Remove the end cope bit and replace it with the groove/ long cut bit.

  16. 16

    Adjust the groove/long cut bit to match opposite the cut made by the end cope bit. This is accomplished by aligning the piece which was cut with the end cut bit to the groove / long cut bit.

  17. 17

    Adjust the router table fence flush with the guide bearing on the bit.

  18. 18

    Cut the length of the rail and stile pieces with the groove/ long cut bit.

  19. 19

    Cut both sides of each 3-inch mullion piece with the groove/long cut bit along the entire length.

  20. 20

    Set the table saw rip fence to cut a 3/4-inch wide piece.

  21. 21

    Rip four mullion pieces to 3/4-inches. These pieces have a profile on one side that was previously cut with the groove/ long cut bit.

  22. 22

    Place each mullion piece inside the previously cut jig and cut the square edge of them with the groove/long cut bit. The jig pieces' profile is opposite of the mullion profile which allows it to be safely cut.

  23. 23

    Divide the mullion pieces into the desired equal lengths and mark the dimensions on them.

  24. 24

    Cut the mullion pieces to the calculated length by subtracting 3/4-inches from the original, previously divided result. This measurement is determined by the divided mullion length. The 3/4 inch less dimension represents the thickness of the intersecting mullion pieces.

  25. 25

    Remove the groove/long cut bit and replace it with the end cope bit and cut the mullion ends.

  1. 1

    Assemble the mullion pieces together by aligning the intersecting pieces together and assemble the sash frame around the mullions without glue.

  2. 2

    Glue all intersecting joints and place a clamp at each end of the sash.

  3. 3

    Diagonally measure each side of the sash to ensure squareness. These dimensions must be exactly the same.

  4. 4

    Remove the clamps when the glue is dry and install two 4-penny finish nails through the rail pieces, into the stiles on each corner.

  5. 5

    Drive the nails below the surface of the frame with the nail set.

  6. 6

    Insert the glass into the rebated side of the sash. This is also the exterior side of the sash which was cut with the groove/long cut bit.

  7. 7

    Place glazing points into the wood sash to hold the glass in place.

  8. 8

    Apply glazing compound to secure the glass.

Tips and warnings

  • Dry fitting the sash together before applying glue will allow for adjustments in the sash.
  • Always use safety glasses when operating machinery. Use push sticks and finger boards to avoid risks of injury.

Don't Miss

  • All types
  • Articles
  • Slideshows
  • Videos
  • Most relevant
  • Most popular
  • Most recent

No articles available

No slideshows available

No videos available

By using the site, you consent to the use of cookies. For more information, please see our Cookie policy.