DIY Network

How to Install Sidelight Sashes

Learn how to install traditional side sashes and create a welcoming front door.

More in Windows Walls and Doors

  • Time


  • Price Range

    $250 - $500

  • Difficulty

    Moderate to Hard


Step 1: Remove the Glass Blocks

The homeowners have glass-block sidelights surrounding their entry door. They feel that the glass blocks are not visually consistent with the period and architecture of their home. So, they want to replace them with more traditional side sashes (Image 1).

Just like bricks, glass blocks are held in place by mortar. Begin by removing the trim pieces and exposing the mortar joint of the glass block. Use a cold chisel and hammer to break out one of the mortar joints (Image 2). If you can successfully loosen the joints, you may be able to pull the blocks out one by one.

If (as in our case) breaking the joints does not work, you may simply have to settle for the "brute strength" option -- breaking out the glass with a hammer. Begin by breaking out the top glass block, cleaning it out and working your way down the row cleaning out all the mortar all the way down.

Scrape out any adhesives, additional mortar or fasteners using a paint scraper, putty knife, pry bar, pliers and hammer.

With the old material removed, a metal lath may be exposed. The metal lath is the surface to which the original blocks were secured. In our case, this was part of what made the removal of the glass blocks so difficult. Continue breaking out all of the blocks as well as the supports that held them (Image 3).

Step 2: Prep the Area for the Sidelights

To prepare the openings for the new sidelights, the damaged wooden jambs must be cleaned up and reconditioned. Sand the newly exposed surfaces to remove all rough spots and smooth the jamb surfaces.

In our case, an old, damaged screen-door latch (Image 1) had to be filled. Use a polyester or epoxy resin filler to fill any damaged areas to the surface and cover any voids (Image 2). We used a two-part wood filler to restore a smooth surface to the damaged jambs. Allow the filler to harden as per the manufacturer's instructions.

Sand the filled-in areas smooth, then sand the entire surface in preparation for primer. Paint on one coat of oil-based primer and let it dry.

Step 3: Install the Sidelight Sashes

Prepare the new sidelight for installation by measuring the existing opening and trim to fit if necessary. In our case, we intentionally ordered the sashes slightly oversized, slightly wider and taller than the opening, then custom cut the sashes to fit.

To cut the sashes to width, they are cut lengthwise using a table saw with a fine-tooth blade (Image 1). Then using a clamped board as an edge-guide and reference, the sashes are cut to length using a circular saw (Image 2).

Check to see if the bottom of the existing threshold is beveled. The bottom of sidelight sash will have to be beveled to match it.

Set the new sidelight sash into place. To secure it in place, nail through the frame of the sash diagonally into the existing wood door jamb (Image 3).

Replace any interior trim at the sidelights, and caulk the interior and exterior. Apply an enamel finish coat of paint.

In our case, there was a slight problem in that the sashes ordered weren't the exact same thickness as the jamb, so when put in place it extended out beyond the face of the jamb just a little too far. To remedy this problem a small rabbet was cut around the edge of the sash (Image 4) so that it would sit flush in the opening.