SKILL LEVEL 3
by Larry Johnston
When a wooden window sash starts coming apart, don’t immediately rip out the whole window and replace it. Whether you have single- or double-hung windows, windows with hinged panes, sliders or storm windows, straightforward repairs on your wooden sash can give the window a new life. Here are some repair techniques you can try.
Larry Johnston writes about home repair, renovation and remodeling between bouts of maintenance on the 1908 house his family calls home. Not so long ago he made four new wooden storm sashes for the big front windows.
3 Skill level
3 out of 5
You can use a steel or brass corner brace to reinforce a loose corner, either as a temporary patch until you can remove the sash for a permanent repair or as a permanent repair if its utilitarian look won’t upset the room aesthetics
The flat, L-shape style works best; buy one that spans the joint between the sash stile (the vertical side piece) and rail (the horizontal crosspiece) and has two screw holes on each end.
With the sash closed, hold the plate across the loose joint on the face of the sash and mark the screw hole locations on the stile. Drill pilot holes for the screws and attach the mending plate to the stile. Then drill pilot holes for the screws in the rail, making them slightly off center, away from the stile — so driving in the countersunk screws draws the joint together more tightly. Screw the plate onto the rail.
If you don't want to do the brace option from step 1, you can either reinforce the sash corners with dowels or disassemble the sash and reglue it. Before you do either, remove the sash. The technique depends on the window style; it's a good idea to have a helper, especially if the window is heavy.
Double- or single-hung
With a utility knife, cut through the paint along the joint between the jamb and the sash stops (the strips that hold the sash in place) along the side of the window.
Carefully loosen and remove the stop on each side by forcing a thin pry bar between the stop and the sash. Pry a little at a time, working the pry bar along the length of the stop to avoid breaking the stop. Holding the sash in place, remove the stops. Pull out any nails still in the jambs.
Pull the sash out of the opening. If the sash has weight cords attached, pull the knotted end out of the sash recess on each side and secure the cords so they won’t fall into the weight channel behind the jambs. If the window has spring counterbalances, remove the attaching screws from the sash.
If you can raise the sash high enough in the jamb to clear the lower stop, tilt the sash and remove it. If not, remove the stops as outlined for a hung window.
Loosen the turn buttons around the window's edge. If you don’t see turn buttons, look for slotted screw heads inset into the face. A fraction of a turn on each one releases the window.
Release or disconnect the supports that hold the window open, if installed.
If the storm window hangs from hinges at the top, swing out the window and lift it up to remove it. Otherwise, tilt the top out and lift the sash clear.
Disconnect or remove any support arms or braces. Support the sash and remove the hinge pins or the screws that attach the hinges to the sash.
On a generally sound sash, dowel reinforcements strengthen a loose corner while remaining mostly invisible on a painted sash. On a stained and sealed sash, the dowels are likely to show, so make them a style feature by adding them in the same locations at both corners on the same rail or at all four corners. Dowels of a contrasting wood — say walnut dowels in an oak sash — give a distinctive look.
Here's how to insert the dowels:
Cut the dowels
Cut two lengths of 3/8-inch dowel rod to the thickness of the sash plus about 1/4 inch. Measure the actual diameter of the dowels, because they might not be exactly 3/8 inch.
Drill the holes
Square up the sash with a framing square or by measuring both diagonals. (When both diagonals are equal, the sash is square. Be careful, however, that you measure to the same points on both diagonals; broken-off or worn-down corners spoil the accuracy.) Clamp the sash square with bar clamps.
Mark center points for two holes on the stile at the loose corner, locating the holes where they will go through the rail tenon where it passes through the stile.
With a twist drill the same diameter as the dowels, drill straight through the stile at each center point. Place a piece of scrap wood under the sash corner to minimize splintering when the drill breaks through the back. To keep the frame from twistig out of square, place a piece of scrap wood the same thickness under each corner.
Insert the dowels
Coat the dowels with woodworking glue and push them into the holes. Tap them in with a soft-face or wooden mallet, if necessary, until each extends about 1/8 inch beyond both faces. Allow the glue to dry according to the label instructions.
With a fine-tooth saw, cut the dowels flush with the stile on both sides. A flush-cutting saw, with the teeth set toward only one side, does a neat job.
Sand the surfaces smooth and touch up the paint or finish.
If your sash is loose and wobbly all around, your best bet might be to disassemble and reglue it. If part of the sash is damaged, rebuilding is your only option. Though the work is pretty straightforward, the job may take some time.
Remove the glass
Because panes of glass aren't uniformly rectangular, place masking tape in the top left corner of each pane, noting its the row and column it's in. That way, you know where each pane goes later, and how it's oriented in it's opening.
Wearing protective eyewear and leather work gloves in case the glass breaks, scrape the glazing compound (putty) from the edges of the glass with a glazing tool, chisel or putty knife. To soften old, hardened glazing compound, you can warm it with a heat gun, taking care not to scorch the wood. Move the heat gun just ahead of your chisel or putty knife for best results. (If wooden stops hold the glass instead of putty, remove them.)
Remove the metal glazing points that retain the glass, and lift the pane out of the sash.
Clean old putty and paint out of the window channel with a putty knife, chisel or stiff wire brush.
Take the sash apart
Pull the rails and stiles apart and remove pane dividers. Work carefully; a joint might have nails or screws in it.
Reassemble the sash
Inspect the stiles, rails, muntins and mullions (dividing strips) for cracks or other damage. You can repair many cracks or splits yourself with glue. Take parts that are beyond repair to a custom millwork or woodworking shop for advice.
Scrape traces of paint, old glue and dirt off joint mating surfaces. Be careful not to pare away so much wood that you make the joint too loose.
Assemble the sash without glue to determine the correct assembly order and to test joint fit.
Glue the joints and assemble the sash.
Square the sash and clamp it, following with the glue instructions.
Paint or finish as necessary.
Reglaze the sash using glazier’s points and glazing compound. Remove the masking tape.
Rinstall the sash, reversing the procedure you followed to remove it. Touch up paint on the jambs and stops as necessary.
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|Corner reinforcement plate, l-shaped|
|Dowel rod, 3/4 in.|
|Glue, slow-set epoxy|
|Glue, woodworking glue|
|Leather work gloves|
|Paint, or stain and sealer|
|Power drill/driver and bits|
|Saw, fine-tooth, preferably flush cutting|
|Soft-face or wooden mallet|