How To Repair and Restore Old Wood Windows

How To Rehabilitate Old Windows

   If you're looking to save money on energy bills by replacing your drafty windows, I think you'll find that repairing your old windows will save you even more.  This is especially true since the life expectancy of new windows is only 15-20 years.  With the cost of having a new window installed reaching a minimum of $189 (plus tax) for a limited-size window, and the cost of repairing an old window reaching a whopping $5-$25, it may be worth a try to learn how to fix the old ones.
   Disassembling and putting back together a window can seem like a daunting task the first time you do it.  You might break or damage something in the process, but everything's fixable, and you surely won't make the same mistake twice.
   The first thing you need to do is assess what kind of condition the window is in and what needs to be done in order to bring it back to life.  Repair may be as simple as glazing and painting, or as complex as complete dis-assembly (which is not as hard as it sounds.)

Glaze and Repaint

   This is the simplest and most important part of keeping a window like new.  Don't disturb the glazing (the hard sealant used around the exterior of the glass,) if it's solidly in place, with no pieces missing.  If it has a large crack along the wood or along the glass, and it falls out when you gently pry it out with your finger, then it's time to reglaze. 
   Use a utility knife inserted between the glazing and the wood to cut along the crack, and the glazing will fall out easily.  If it doesn't, don't force it or you may break the glass.  Clean the glass with a sharp putty knife, again, being gentle so as to not break the glass.  If the glass is loose, use a glazing point to resecure the glass, sliding it into the wood with a putty knife.  Glazing points are sold next to the buckets of glazing compound in the paint department of home improvement stores.
  Next, clean out the groove with your utility knive, putty knife, and a broom or whisk.  Blowing out the dust and debris doesn't hurt either.    Some experts recommend applying linseed oil to the bare wood to make the glazing stick better.  Apply glazing with a glazing tool (also sold near the glazing compound).  Only apply enough to cover the channel.  Don't put on so much that it's visible from the interior.  Smooth it out with the tool.  This will take some practice.  There are several methods of applying glazing, and you'll find one that suits you.
  After at least seven days of 40 degree weather, prime the glazing with oil base primer.  I like to use small foam throwaway brushes because they're cheap, and oil is hard to clean out of a brush.  Then paint the sash with the color of your choice and you're done!

Replace or Reattach Ropes

  If your ropes are broken, it's not as hard as you may think to solve this problem.  This process involves removal of the lower sash and some trim.
  The first thing you need to do is carefully remove one of the vertical inside stops that hold the lower sash in place.  There is one on each side of the window.  If you only have broken rope on one side of the window, you only have to remove the stop on that side.  Use a stiff scraper blade inserted underneath the back side, and something soft under the blade handle to keep from marring the rest of your trim.  Pry loose the stop, starting at the bottom, and working your way up a little at a time.  If there is a stop along the bottom of the window, this must be removed first.  If you have a hard time removing the stop, check for a buildup of paint, and remove that buildup before prying, other wise you'll end up with two pieces of wood instead of one.  This is a case where two is NOT better than one.
  After the stop is removed, check for metal weatherstrip along the side of the sash.  If you have the kind of weatherstripping that has something that is bent in a shape that inserts into a groove in the window, it will have a small nail holding it at the top, bottom, and sometimes halfway down or anywhere in between.  First, pry out the nail by hammering a wood chisel underneath the weatherstripping, behind where the nail is.  Then pry out the nail a little bit and pull it out the rest of the way with a pair of pliers or a pry bar hooked underneath the nail head.  It's easiest to pull out the nail at the top of the weatherstripping first, then open the window and pull out the rest.  You only need to remove the weatherstripping from one side of the lower sash.
  At this point you can pull out the lower sash a little bit on the side where the weatherstripping was removed.  The easiest position for the window to be in while your doing this is the lowered position, opened slightly, so that it will come out without hitting anything.  Once it is pulled toward you, you can then pull it sideways out of the other side as well.
   If either of the ropes are still attached, remove the nail that holds them in place with a pair of pliers.  Rest the window on the sill while you're doing this, and catch it so that it doesn't fall.  At the same time, hang on to the rope if it's still attached to a weight so that it doesn't fall into the cavity.  Tie a simple knot in the end of the rope and that will keep it from falling into the pulley.  Discard any broken rope that you remove from the sash, and rest the window where it will be out of the way for a while.  This is a good time to clean out the weatherstripping on the top of the lower sash and the bottom of the upper sash with a screwdriver and/or vacuum.  These are called meeting rails, because they're located where the two sashes meet.  Cleaning these out will ensure that the window closes and seals properly.
   On the side of the window that has the broken or missing rope, you'll need to remove the parting stop that runs vertically along the center, in between where the upper and lower sashes slide.  It measures 1/2 inch by 3/4 inch, and runs the entire height of the window opening.  Before you do this, halfway up the parting stop, there might be a tiny weatherstripping item that is made of metal, with felt behind it.  If it is there, and it is attached to the parting stop, pry out the two nails that hold it in place, with the wood chisel and a hammer. 
   The parting stop is removable by inserting a flat blade screwdriver, tapping the screwdriver with a hammer until it is about 3/8ths of an inch in, then prying on the screwdriver until it comes out a little bit.  Do this every 12 inches or so until the whole parting stop is loose.  When you've pried it out as far as it will go, move the parting stop toward you and it will come out.
   The next task is to look for a rectangular cutout where you removed the large piece of weatherstripping.  If it is held in place with a screw, you're lucky.  If it held in place with a nail, you're not.  Tap upward into the crack underneath the wood where the nail is with the wood chisel and pry on the cutout until it comes out far enough for you to pull it down and out.  If you can, remove the nail before you do this.
   Inside the hole you should see two weights.  One is for the upper sash and one is for the lower.  Remove the weight that aligns with the lower sash by lifting it and pulling out the bottom of the weight.  Remove the broken rope if it's still attached. 
   To install fresh rope, you'll need a package of "Sash Cord" that corresponds with the diameter of rope your windows had.  This is usually 3/8ths inch.  Don't buy clothesline cord because it's stretches too much.  You'll also need a length of bead-- the kind that is used for ceiling fan pulls, and you'll need some 2" masking tape.  Attach the bead to the end of the new rope with masking tape, and lower the bead through the pulley and into the weight cavity.  When you see the bead inside the cutout hole, pull it until the rope comes through.  Attach the rope to the weight with a knot, make sure it's tight, and cut off excess rope on the knot.  Put the weight back in the cavity and pull the slack out of other end of the rope.  Cut off the rope, leaving about 12 inches hanging out of the pulley.  Reinstall the parting stop and the small weatherstripping felt exactly where they were.  Use a smaller hammer with a square head to tap the parting stop back into the groove.
   Set the window sash back on the sill, untie the knot that you tied earlier on the good side, and reattach it exactly where it was, using the same nail and nail hole. Slide the window sash back onto the weatherstripping on the side where you left the weatherstripping on.  Leave the other side of the sash hanging out, but hold onto it.  Pull the new rope down until it won't go any farther, then let it go back in a couple of inches.  Attach it to the sash precisely where you stopped, using the original nail or one similar to it.  The place where you attach it is critical to the operation of the window later on. 
  Place the large weatherstripping back on the sash and slide the window back in.  If there were any shims behind the weatherstripping, slide those in there too.  If the window seems loose from side to side, you can add some drywall shims in there.  These are found in the putty knife section of the drywall aisle at home improvement stores.  Pull down on the weatherstripping until it aligns with the weatherstripping on the sill.  Open the window fully, and reattach the nails that held the weatherstripping in place.  Close the window to reattach the top nail on the weatherstripping.  Reattach the inside stop exactly where it was, inserting the existing nails in their original holes.  Tap each nail a little at a time up and down the stop, to avoid breaking it. 
   Open and close the window to see how it works or if you need to do any adjustment, etc., and you're done!  You can use these methods to reattach the ropes on the upper sash if you like, and if so, you will enjoy the benefits of a fully functional double-hung window--easy cleaning, and the ability to open the top sash for ventilation, even when it's raining.

The Benefits of Old Wood Window Restoration

    Windows that were built before our grandparents were born had a quality of workmanship that you don't find in new windows today.  I'm not talking about energy efficiency here, but that certainly was a part of the old window design.
   Before you get fed up with drafty, loose, or broken old windows, take a few moments and think about how original windows compare with modern equivalents:

Materials Used In Construction

Windows over 100 years old generally were built of hardwoods, which last significantly longer than new pine replacements.  They are commonly known to last 50-100 years with little or no maintenance, and can last indefinitely with a little maintenance every 25-50 years.  Even among wood replacement windows, the original thickness of the wood is something that is almost unheard of today. 


If you have a better model of original window, it came with interlocking metal weatherstripping.  It is long lasting and provides a superior seal.  New windows use different styles of plastic channels, which can become brittle after 15-20 years.  Pile weatherstrips naturally become matted like a carpet and begin to leak air.

Rope and Pulley Lift and Hold Mechanisms

Ropes and pulleys were intended to allow you to lift a window with one finger and keep it in place when you let go.  New windows, without exception, use other types of spring methods, made of a combination of metal and plastic, but mostly plastic.  Holding methods such as this sometimes don't last more than a year before they start to lose their holding power.  Some have no holding method other than fitting the window tightly in the channel, which can make the window difficult to open and close, or allow air to enter through the sides. 

Style and Flexibility

Large, perfectly flat glass was not widely available, so older windows tend to have wavy glass with an antique look, divided into many "lights" or smaller panes separated by muntins.  This adds character to a house, and interest to the view from the inside.  Wood construction also allows the homeowner to choose from an unlimited palette of colors when painting the outside of the house.  White was not used much during the late 19th century, so typical vinyl windows can look quite strange on a Victorian home.

Wood Window Maintenance Checklist

The key to making sure old windows last indefinitely is maintenance.  Here are a few things to check, if you want to avoid the more lengthy processes involved in window rehabilitation.

Keep a good coat of paint on the exterior at all times.

Don't allow it to peel itself down to bare wood, or you'll invite bigger problems of dry rot and air/water/snow infiltration.  In addition, if you allow it to get so bad that cracks appear, water can get in, freeze, and make the windows come apart.

However, that doesn't mean to paint the window shut.

Double hung windows were designed, especially in larger two and three story homes, to allow for easy cleaning by lowering the upper sash, reaching out and wiping it clean, without the aid of a 40 foot ladder and a lot of guts.  If you're having the house painted, make sure you open and close the windows several times while the paint is still fresh, and also soon after it dries.  You'll regret it later on if you don't.

Check the glazing at the bottom of the glass.

This is critical to stopping the wood from rotting out at the bottom, because it keeps water out.

Don't paint the ropes.

This makes them brittle.  Unpainted ropes can last a lifetime.  This is not so with painted ones.

Vacuum out the weatherstripping channel.

Vacuum out the bottom of the window from time to time, or whenever stuff falls in.  Windows won't seal properly if they can't be closed all the way.  They can't be fully latched either.  Forcing them closed will only put gouges in the wood, or break the glass.

If all of these guidelines are followed, you won't need the advice in the rehabilitation section.

How To Replace Window Glass

  If you only have a small crack in antique glass, its perfectly acceptable to leave it as is, from a historical preservation standpoint.  If the window is broken out though, I don't think anyone would have a problem with you replacing it.  Use gloves and safety goggles, and pull out what glass is left, along with the attached glazing.  Any remaining glazing can be removed using the techniques in the Glazing section.  Run your tool along the opening to check for old glazing points that may still be embedded in the wood.  Remove all of them with needle-nosed pliers. 
   Measure the length and width of the glass opening, taking three measurements each, at different points along the opening.  This is done because sometimes windows are not perfectly square and straight.  Take the smallest measurements, subtract 1/8th of an inch, and give them to your local hardware store or glass company. 
   Before resetting the glass, apply a 1/8th inch thick bed of glazing compound to the opening.  The glass will sit up against this, and it will provide a better air seal, as well as add cushioning protection for the glass.  After setting the glass, secure it firmly, but gently, with glazing points.  Use two points for each side that is longer than two feet.  If the window is more than four feet in width or height, glazing compound is not recommended.  Finally, glaze, prime, and paint as outlined in the Glazing section.

How To Repair or Replace Weatherstripping

   The best old window weatherstripping you'll find is interlocking metal weatherstrip.  It's far superior to spring bronze or no weatherstripping at all, which you may find on some old windows.  If you have any missing or damaged pieces, there are several websites that have a variety of styles, and some of the companies have been around for over 100 years.  Do a search on "interlocking metal weatherstrip" to find one that appeals to you.  I recommend visiting the Accurate Metal Weatherstrip Co. Inc. site, to see the variety of metal weatherstripping that is available.
   If the weatherstripping looks intact, but doesn't work properly, you can bend it back into position, so that it lines up with the grooves on the window sash.  The small piece that attaches to the parting stop where the two sashes meet can be reproduced easily if it's missing.  Cut a small piece of sheet metal into a strip about 1/2 inch by 2 or 3 inches and make a small fold on each end.  Cut a small piece of felt weatherstripping (it's sold in a small roll) to fit underneath the metal and tuck it inside the folds.  Then slide the assembly into the gap where you're having air infiltration, and drive 3/4 inch 18oz wire nails through the assembly into the parting stop, one nail at the top and one at the bottom.  This is the most overlooked part of the metal weatherstripping system, but the one that will make the most difference in energy efficiency.

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