How to Fix Double Hung Windows

Double hung wood windows are popular because they are attractive and traditional. They can be opened to admit cool summer breezes but shut tightly against cold winter winds. Their construction is simple --- two movable windows, or sashes, controlled by counterweights hanging in channels on both sides of the window frame allowing motion up and down along stops attached to the side jambs. Several things can go wrong with double hung windows but they're all easily remedied with a few tools and readily available replacement parts.

Difficulty: Moderate

Instructions

Things You'll Need:

• Mallet and hammer
• Screwdriver
• Pry-bar or upholstery pry-tool
• Utility knife
• Saw and miter box
• Measuring tape
• Caulking and insulation
• Rust-resistant wood screws and finish nails
• Paraffin or a bar of soap
• Options and replacement parts:
• Glazers' points and window putty
• Paint
• Sash cord
• Sash kit
• Jamb liners
• Jig saw
• Wood trim pieces
• Stop trim

1. 
    
   Top and bottom sashes

   Look for the simple answer first. All double hung windows have sashes suspended between stops running up and down the side (or jamb) of the window. A bit of soap or paraffin along the jambs may free a sticky sash. If the sash can't be freed, try cutting the layer of paint or varnish that bonds it to the jamb or along the stop. If it won't stay up, though, or the glass is broken, you'll have to take the window apart.

2. 
    
   Double hung windows have three stops to hold sashes

   Remove a sash for re-glazing or repair by pulling out the inner stop with a pry-tool. Tip the sash out slowly and carefully pull the sash cord out of its slot along the side of the sash, then tie it off so it won't fall into the well alongside the window. If the outer sash is broken, repeat the process, prying out the parting stop that separates the sashes in the window frame and carefully tying off the sash cords. If the window is newer or was installed with vinyl jamb liners, remove the sashes by raising the sash halfway and unclipping the sash from the liner --- these easy-to-manage spring-loaded mechanisms have replaced the old weight-and-rope counterweights, making removal and replacement simpler.

3. Re-glaze a sash by digging out the putty that holds the glass in (usually on the exterior of the window), removing the broken glass and cleaning out the pane. Set a new piece of glass, secure it with diamond-shaped metal points and putty around the frame. Let the putty dry completely before painting the window with exterior paint. Replace broken vinyl or wood sashes by replacing the sash with a sash kit available from the window manufacturer --- simply slide in a new sash and replace the stop or stops.

4. 
    
   Jamb liners allow easy removal and cleaning of sashes

   Solve existing or future counterweight problems by restringing weights. Unscrew the plate that holds the pulley over which the cord moves and carefully pull the heavy weight up and out of the well next to the frame. Tie a new piece of sash cord or best-quality heavy cotton clothesline rope of the same diameter to the weight and cut to the same length as the old cord. Tie a knot at the end of the rope and lay it into the cord slot on the sash so that it lays flat. To replace the counterweights with vinyl jamb liners, drop the weight cord into the side well and remove the pulley plate, then attach the jamb liner and sash clips as directed with flat-headed wood screws.

5. 
    
   Be sure to read directions and fasten all the clips when installing new parts.

   Complete repairs and paint wood sashes before reinstalling. If the sash fits too tightly, sand the sides of the sash --- the thickness of paint can make it bind. Sand any built-up paint off the jambs and stops before reinstalling the stops to prevent binding. Reinstalling a sash between jamb liners involves catching the clip on the sash to the latch on the liner spring and tilting the window back in. Replace weak or broken stops with new trim.

Tips & Warnings

• Whether replacing sash cords or installing new jamb liners, keep the channels in which the sashes slide clear of rope, screw heads or anything that might bind the movement of the sash. Chains are also available to replace sash cords, but rope sash cords cost less and can last as long as the house.
• When working with old counter-weighted windows, be careful. The weights are heavy and, if the cord slips, the weight and the cord will plummet down into the well and land on the floor behind the wall with a crash. Always wear eye protection when using power or hand tools.

References

• Jamb Liners
• Sash Repairs

Resources

• Double-hung Q and A