5 tips for repairing double-hung windows

July 28, 2015

Having to replace an entire double-hung window can be an expensive undertaking. Luckily, it is possible to repair and replace parts of the window instead with these five tips. 

5 tips for repairing double-hung windows

1. How to replace a broken windowpane

  • Buy a piece of glass cut 3 millimetres (.12 inch) smaller than the broken window.
  • Carefully remove the broken glass. Then chip out all the old compound around the opening without damaging the wood. Use a hair dryer or heat gun to soften stubborn chunks.
  • Coat the exposed wood in the opening with linseed oil and let it soak in well. Line the opening with a thin bead of compound, and press the new piece of glass into place.
  • Use a putty knife to push new glazing points into place against the glass every 10 centimetres (four inches) around the perimeter. Don't use the old holes.
  • Apply more compound over the glazing points and around the exposed edges of the glass, dipping the putty knife in linseed oil to keep it from sticking to the compound. Let the compound cure for about a week before repainting.

2. How to replace a sash cord with chain

  •  Working on the side with the broken cord, unscrew or pry out the inner stop — the vertical moulding strip that holds the sash in place. Also remove and save any metal weather stripping.
  • Remove the end of the broken sash cord from the channel. Disconnect the sash cord from the other side of the sash, and if it's intact, tie its end to a pencil to keep it from slipping over the pulley. Set the sash aside.
  • Unscrew or pry open the counterweight pocket door on the side with the broken cord. Pull out the weight and remove the cord. Use cutting pliers to cut a chain 30 centimetres (12 inches) longer than the broken cord.
  • To install the chain, slip a nail through a link in one end, then feed the other end over the pulley and pull it out through the access hole. Loop the chain end through the eye of the weight, securing it with wire or manufacturer-provided clips. Slip the weight back inside the chamber.
  • Put the sash back on the sill and refasten the intact cord. Pull the new chain down until the weight hits the pulley; then lower it about five centimetres (2 inches). Remove the nail from the free end of the chain, and secure it to the sash with two centimetre (2/3 inch), number 6 wood screws through two of its links.

3. Replacing crumbly window putty

  • Window putty keeps water from soaking into the wood sashes and rotting them.
  • Replace cracked or brittle compound by chipping it out with a chisel or a five-in-one painter's tool and spreading on a new coat.

4. Gluing cracks in glass

  • A small crack in a windowpane can morph into a big problem. As soon as you see a crack, fill it with industrial glue.
  • Squirt the glue directly from the container into the crack. Any excess will dry to a clear, invisible finish.

Repairing rotted windowsills

  • Chisel away the rotted wood and scrape paint from other soft areas.
  • Drill 0.5 centimetre (.20 inch) holes in the damaged areas, and soak them with liquid consolidant.
  • Quickly apply the epoxy filler, gradually building up the sill to its original level.
  • Smooth with a putty knife dipped in lacquer thinner to prevent it from sticking.
  • Smooth with 100-grit sandpaper; prime and paint.
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