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Launch Slideshow

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Weatherstripping Double-Hung Windows

A guide to ugrading older units that are worth saving

Weatherstripping Double-Hung Windows

A guide to ugrading older units that are worth saving

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    Tom O'Brien

    The author believes that windows should be replaced if they're falling apart, but that most nominally sound windows old enough to have sash weights deserve an upgrade rather than a toss in the dumpster.

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    Figure 1. A lead-safe work zone is needed when working with old double-hungs (A). A spring clamp prevents the sash cord from dropping into the pocket; on the window shown (B), the trim was in bad shape and was removed for replacement, allowing the author to insulate the cavity with XPS and spray foam. To improve the windows operation, old paint is removed from all running surfaces; here the author uses an infrared paint-stripping tool (C). Paint is also removed from the inside of the window frame and the edge of the stop (D); raw wood surfaces will be waxed.

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    Figure 1. A lead-safe work zone is needed when working with old double-hungs (A). A spring clamp prevents the sash cord from dropping into the pocket; on the window shown (B), the trim was in bad shape and was removed for replacement, allowing the author to insulate the cavity with XPS and spray foam. To improve the windows operation, old paint is removed from all running surfaces; here the author uses an infrared paint-stripping tool (C). Paint is also removed from the inside of the window frame and the edge of the stop (D); raw wood surfaces will be waxed.

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    Tom O'Brien

    Since old windows of this type typically have some lead paint on them, I set up a lead-safe work space around each of the window frames, and take appropriate safety measures while preparing the sash and stops for weatherstripping.

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    Tom O'Brien

    A spring clamp prevents the sash cord from dropping into the pocket; on the window shown, the trim was in bad shape and was removed for replacement, allowing the author to insulate the cavity with XPS and spray foam.

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    Tom O'Brien

    To improve the window’s operation, old paint is removed from all running surfaces; here the author uses an infrared paint-stripping tool.

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    Tom O'Brien

    Paint is also removed from the inside of the window frame and the edge of the stop; raw wood surfaces will be waxed.

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    Figure 2. After years of weatherstripping old windows and doors, the author has settled on three seal profiles for most jobs: a polypropylene brush seal for the sides; a 14-inch tube seal (white or bronze) for the meeting rail, and a white 316-inch tube for the bottom (A). Slots for the seals are cut with a 3-millimeter slot cutter (B); the seals are installed with a screen tool or by hand (C).

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    Figure 2. After years of weatherstripping old windows and doors, the author has settled on three seal profiles for most jobs: a polypropylene brush seal for the sides; a 14-inch tube seal (white or bronze) for the meeting rail, and a white 316-inch tube for the bottom (A). Slots for the seals are cut with a 3-millimeter slot cutter (B); the seals are installed with a screen tool or by hand (C).

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    Tom O'Brien

    After years of weatherstripping old windows and doors, the author has settled on three seal profiles for most jobs: a polypropylene brush seal for the sides; a 1/4-inch tube seal (white or bronze) for the meeting rail, and a white 3/16-inch tube for the bottom.

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    Tom O'Brien

    Slots for the seals are cut with a 3-millimeter slot cutter.

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    Tom O'Brien

    The seals are installed with a screen tool or by hand.

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    Figure 3. The bottom edge of the sash must be trimmed by about 18 inch to account for the thickness of the weather seal (above). After the cut, the end grain gets a treatment of epoxy consolidant to prevent rot infestation (left).

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    Figure 3. The bottom edge of the sash must be trimmed by about 18 inch to account for the thickness of the weather seal (above). After the cut, the end grain gets a treatment of epoxy consolidant to prevent rot infestation (left).

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    Tom O'Brien

    The bottom edge of the sash must be trimmed by about 1/8 inch to account for the thickness of the weather seal.

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    Tom O'Brien

    After the cut, the end grain gets a treatment of epoxy consolidant to prevent rot infestation.

  • Figure 4. Using a plunge router, the author centers the slot for the bottom tube seal 58 inch from the face of the sash (A); the slot for the meeting-rail seal is centered 38 inch below the top edge (B). The side brush seals are placed as close to the edge as practical  14 inch (C). Any closer and the thin strip of wood left behind may break off.

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    Figure 4. Using a plunge router, the author centers the slot for the bottom tube seal 58 inch from the face of the sash (A); the slot for the meeting-rail seal is centered 38 inch below the top edge (B). The side brush seals are placed as close to the edge as practical 14 inch (C). Any closer and the thin strip of wood left behind may break off.

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    Tom O'Brien

    Using a plunge router, the author centers the slot for the bottom tube seal 5/8 inch from the face of the sash.

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    Tom O'Brien

    The slot for the meeting-rail seal is centered 3/8 inch below the top edge.

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    Tom O'Brien

    The side brush seals are placed as close to the edge as practical — about 1/4 inch. Any closer and the thin strip of wood left behind may break off.

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    Figure 5. Before the weatherstripped sash can be reinstalled, the stool must be scribed and trimmed to allow for the thickness of the brush seals on the face of the side rails. A 1/16-inch-wide gap, scribed with a carpenters pencil, allows for expansion (top). A bullnose plane with a removable toepiece cuts away the excess stock with a minimum of dust (above).

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    Figure 5. Before the weatherstripped sash can be reinstalled, the stool must be scribed and trimmed to allow for the thickness of the brush seals on the face of the side rails. A 1/16-inch-wide gap, scribed with a carpenters pencil, allows for expansion (top). A bullnose plane with a removable toepiece cuts away the excess stock with a minimum of dust (above).

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    Tom O'Brien

    Before the weatherstripped sash can be reinstalled, the stool must be scribed and trimmed to allow for the thickness of the brush seals on the face of the side rails. A 1/16-inch-wide gap, scribed with a carpenter’s pencil, allows for expansion.

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    Tom O'Brien

    A bullnose plane with a removable toepiece cuts away the excess stock with a minimum of dust.

Launch Slideshow

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Guide to Upgrading Older Units

Diagnosing problems, removing and stripping old sashes

Guide to Upgrading Older Units

Diagnosing problems, removing and stripping old sashes

  • Image

    http://www.jlconline.com/Images/tmp6AF5%2Etmp_tcm96-1488786.jpg

    true

    Image

    600

    Tom O'Brien

    The author believes that windows should be replaced if they're falling apart, but that most nominally sound windows old enough to have sash weights deserve an upgrade rather than a toss in the dumpster.

  • IMG_0337.JPG

    Figure 1. A lead-safe work zone is needed when working with old double-hungs (A). A spring clamp prevents the sash cord from dropping into the pocket; on the window shown (B), the trim was in bad shape and was removed for replacement, allowing the author to insulate the cavity with XPS and spray foam. To improve the windows operation, old paint is removed from all running surfaces; here the author uses an infrared paint-stripping tool (C). Paint is also removed from the inside of the window frame and the edge of the stop (D); raw wood surfaces will be waxed.

    http://www.jlconline.com/Images/tmp6AF8%2Etmp_tcm96-1488789.jpg

    true

    Figure 1. A lead-safe work zone is needed when working with old double-hungs (A). A spring clamp prevents the sash cord from dropping into the pocket; on the window shown (B), the trim was in bad shape and was removed for replacement, allowing the author to insulate the cavity with XPS and spray foam. To improve the windows operation, old paint is removed from all running surfaces; here the author uses an infrared paint-stripping tool (C). Paint is also removed from the inside of the window frame and the edge of the stop (D); raw wood surfaces will be waxed.

    600

    Tom O'Brien

    Since old windows of this type typically have some lead paint on them, I set up a lead-safe work space around each of the window frames, and take appropriate safety measures while preparing the sash and stops for weatherstripping.

  • IMG_8405

    Image

    http://www.jlconline.com/Images/tmp6AF6%2Etmp_tcm96-1488787.jpg

    true

    Image

    600

    Tom O'Brien

    A spring clamp prevents the sash cord from dropping into the pocket; on the window shown, the trim was in bad shape and was removed for replacement, allowing the author to insulate the cavity with XPS and spray foam.

  • Image

    http://www.jlconline.com/Images/tmp6AF9%2Etmp_tcm96-1488790.jpg

    true

    Image

    600

    Tom O'Brien

    To improve the window’s operation, old paint is removed from all running surfaces; here the author uses an infrared paint-stripping tool.

  • O'Brien_fig8

    Image

    http://www.jlconline.com/Images/tmp6AFA%2Etmp_tcm96-1488791.jpg

    true

    Image

    600

    Tom O'Brien

    Paint is also removed from the inside of the window frame and the edge of the stop; raw wood surfaces will be waxed.

There’s money to be made from replacing old windows, and sometimes a complete replacement makes sense for the homeowner, too, especially if the windows in question were never built to last. But in most cases, the hoped-for energy savings simply don’t justify the expense of tearing out and disposing of an otherwise sound wood sash. In my experience, any window that’s old enough to have weights and cords deserves an upgrade rather than a toss in the dumpster.

Homeowners considering a window replacement almost always bring up energy concerns, but their bigger beef is that the units operate poorly — usually because over the years too much paint has been applied in the wrong places. After I’ve cleaned and weatherstripped an old sash, it fits tightly, yet goes up and down with the touch of a finger.

Double-Hung to Single

Back in the days before A/C and active ventilation systems, double-hung windows promoted air circulation when the bottom sash was raised and the top sash lowered. Most of the older windows I encounter have top sashes that haven’t moved in decades and storm windows that are only screened for the lower sash. So unless the owner insists on having two operable sashes, I simply make sure that the upper unit is square and secure. If it’s loose, I toenail it in place with a pair of 3-inch trim screws driven upward through each side of the bottom rail, then caulk the edges.

Removing the Sash

Taking out a lower sash simply requires prying off one stop and disconnecting the cords, but I remove both stops because they will need to be ripped down slightly to accommodate the thickness of the weather seals. After I disconnect each sash cord, I attach a spring clamp to prevent the weight from falling to the bottom of the weight box (see slideshow). If I’m working on more than one window, I mark an indelible code on each of the pieces to ensure that everything goes back in the right place.

Since old windows of this type typically have some lead paint on them, I set up a lead-safe work space around each of the window frames, and take appropriate safety measures while preparing the sash and stops for weatherstripping.

Sashes that are in rough shape — with extensive wood rot, flaking paint, separated joints, cracked panes, or crumbling glazing — need to be completely stripped and repaired. But if the sash is generally sound, I simply remove the paint from the surfaces that are to be fitted with weather seals or that are subject to abrasion. For this task I use an infrared paint remover (around $500 from Eco-Strip, 703/476-6222, eco-strip.com), which breaks the bond between the paint and substrate without releasing lead fumes. The tool is an investment, but worth it if you plan to do a lot of this work; nothing is faster.

After the paint is gone, I give the bare wood surfaces a light sanding with 100-grit paper in a random orbit sander attached to a HEPA vac.