84 FINE HOMEBUILDING

Yes, they’re worth fixing. Those old windows were built better (and frombetter wood) than anything you can buy today.

BY DAVID GIBNEY

Sashes

Other than a lighted match, noth-ing will ruin the charm of anold house faster than rippingout the original double-hung

windows. But if your windows are oldenough to have sash cords, pulleys, andweights—and especially if they’ve fallen intodisrepair—you might be tempted by thoseads that promise huge energy savings and nomaintenance if you replace the windows.What they won’t tell you is that energy-wise,you’d get a much better return on your in-vestment simply by repairing existing win-dows and adding high-quality stormwindows (sidebar p. 89).

From my perspective, it makes no sense toremove window units that have survived fora century or more and to replace them withsomething that may not last a decade beforethe finger-jointed wood frame rots or thevinyl cladding deteriorates or the double-glazed seals rupture. Why not spend a littletime, and a lot less money, to help your ex-isting windows last another century?

They don’t make them like they used toMaterials vary by region, but most of the oldwindows that I see are crafted from first-growth, vertical-grain pine. This remarkablestuff is dimensionally stable and highly rot-resistant, far superior to anything available today. Old-growth pine is so durable and for-giving that even though they may look bad,most of the windows I’m asked to repair (orreplace) generally require little more than mi-nor touch-ups and a bit of reglazing.

If your house is 100 or more years old and ifyou’re lucky, you still might have the originalhandblown glass. This important feature de-notes early windows. Depending on whenthey were made and what raw materials were

WindowRestoring

Photo this page: Randy O’Rourke

If a window sash needs ma-jor repairs, both glass andpaint usually have to comeoff. To get at the glass, Istart by hand-scraping theoutside of the frame wherethe wood meets the glazingputty; removing the overlap-ping paint helps to breakthe bond between the twomaterials. 1 For putty re-moval, I depend mostly on aFein MultiMaster (800-441-9878; www.feinus.com),which is set up with a vibrat-ing scraper. Coming in flatover the glass loosens mostof the putty, but it can beslow going. If the putty isrock hard, I attack first withmy 33⁄8-in. cordless Makitacircular saw, but this processrequires a skilled hand. I setthe depth of the blade sothat it will not touch theglass, then carefully cutalongside the shoulder ofthe frame. After the saw cut,the remaining putty goesquietly. 2 Once all the puttyis gone, I slide a scraperalong the surface of theglass to remove the oldglazier’s points. 3 To cut outany putty embedded be-tween glass and wood, I runa knife blade along the edgeof the glass. Then all it takesis a gentle push up from thebottom side to free theglass. 4 I use an electricpaint remover (Warner ToolProducts;www.warnertool.com; 877-992-7637) to strip the flatsections of the sash. 5 Aheat gun in combinationwith a contoured scrapertakes care of the profiles.

FEBRUARY/MARCH 2004 85

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54

REMOVINGPUTTY ANDPAINT IS THEHARD PART

used, some window panes are rippled like theocean, and others are bubbled or scatteredwith bull’s-eyes. Each pane, though, is unique.On the rare occasion when I find a windowthat’s not salvageable, I always save the glass.

If you’re seeking sources for old glass, checkfirst with salvage contractors in your area orwith window-replacement contractors, mostof whom will be happy to let you haul awaythe old sashes that they take out. If those op-tions don’t pan out, I know of one supplier(Fairview Glass Co.; www.fairviewglass.com;301-371-3364) that ships glass nationwide.

Window frames rarely need fixingI inspect the window frames as well as thesashes. Like a dentist with a pick, I use ascratch awl to poke around rotted areas to de-termine the extent of damage. Fortunately,unless the house in question has sufferedfrom serious moisture problems, the framesare almost always rock solid, which is why somany manufacturers have come out with re-placement window units that fit within ex-isting frames. If I find some frame rot, it’susually confined to the end grain where theside jamb meets the sill or to the top portionof the sill itself. These infestations are cleanedout and repaired easily with epoxy (see FHB#107, pp. 60-65, or read this article at www.finehomebuilding.com).

If serious damage has occurred, it’s mostlikely to involve the sashes, particularly thelower sash, because they are used and abusedthe most. If sash rot is minor and localized, Imake the repairs in place. But whenever I dis-cover a serious problem such as a severely rot-ted bottom rail or side jamb, or a broken orrotted muntin strip, I remove that particularsash and make the repair in the shop. Only ifthe bottom and both sides are missing do Iconsider a sash to be beyond repair.

Disassembly requires care, especially with old glassAs I remove each sash, I hold it up to a lightsource and take note of which panes of glassare original so that I remember to take spe-cial care to save them. Removing old glasswithout breaking it is a tedious process at best.Sometimes I find that the old glazing putty isso loose that it just needs a good nudge witha paint scraper to get it off; oftentimes, how-ever, the putty is as hard as rock.

Plenty of tools and techniques are availablefor removing stubborn old glazing putty, and

none of them is perfect. I’ve had lots of suc-cess using a Fein MultiMaster tool along witha small Makita cordless circular saw to breakup old putty, but this process is not for thesqueamish (sidebar p. 85).

If you’ve tried to remove the glass withoutsuccess, you might be able to find a localwindow-repair or paint-removal specialistwho can help. Or you might attempt the repairwith the glass in place. You also might wantto check out a new infrared paint-removaltool that claims to be equally effective for re-moving glazing putty (see FHB #150, p. 114).

Epoxy repairs minor damageAfter all the glass has been removed and care-fully set aside, the built-up layers of paint arenext to go. Old windows almost always haveat least one layer of lead paint on them, so it’simportant to take some safety precautions (seeFHB #150, pp. 66-73, or read this article atwww.finehomebuilding.com). If I have an

86 FINE HOMEBUILDING

Use a utilityknife to breakthe paint sealfrom thewindow stop.

Remove the windowstop using a small prybar over a stiff-bladedputty knife.

Pull out thelower sash.

Pierce the sashcord with a smallfinish nail toprevent sashweights fromdropping to thebottom of theweight cavity.

To access the upper sash,remove the parting bead bygrasping tightly and pullingstraight back.

Window stop

REMOVINGTHE WINDOW SASH

REPAIR SASH WITH OLD WOODAND EPOXY

1

Parting bead

Vise-Grip lockingsheet-metal tool(www.irwin.com;800-464-7946)

Drawings: Chuck Lockhart

FEBRUARY/MARCH 2004 87

Why not spend a little time, and a lot less money, to help your existing windows last another century?

www.westsystem.com); the heat treatment al-lows the liquid epoxy to travel deep into thewood’s fibers, creating a superior bond. Assoon as the wood fibers refuse to absorb anymore of the liquid, I spread on a fine skimcoat of solid epoxy filler to create a smoothfinish surface.

Parts and patches are made fromthe same wood as the sashUnlike fixed trim elements, a window sash issubject to a great deal of mechanical stress.To ensure that my repairs last as long as pos-sible, I don’t depend on epoxy to fill largegaps; instead, I fashion all but the smallestpatches from wood. I rely on a dutchman (a

patch that is made with wood) glued with anepoxy adhesive from West Systems to repairdamage that would require more than a skimcoat of filler (photos below).

When I have to replace an entire sash part,such as a rail or a muntin strip, I first try toscrounge up a match in a local salvage yard.But if that doesn’t pan out, I can replicate theprofile using a molding head cutter that fitsmy tablesaw. (To find out how to make a cus-tom molding cutter, visit our Web site atwww.finehomebuilding.com.) If just a por-tion of the original piece is damaged, I cut backto sound wood and splice new wood to old.

Whether it’s a small dutchman or an entirebottom rail, every replacement part should be

entire house’s worth of windows to repair, Isend them to a reputable paint stripper, wherethe paint can be removed safely. If I have justa few windows to repair, I strip the paint my-self using low-temperature heat strippers(photo bottom right, p. 85) or chemicals (Backto Nature Products; 800-423-7733;www.ibacktonature.com).

If the sashes have any minor cases of rot orsimple weather damage, they are repairedwith epoxy. First, I gently wire-brush the sur-face free of all loose wood fibers. Next, I care-fully warm the wood surface with a heat gunset on its lowest setting. Using a disposablepaintbrush, I apply generous amounts of aliquid epoxy (West System; 989-684-7286;

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1 Deep gouges and rot are carved out and squared up with achisel to make room for a wooden patch (commonly called adutchman) that’s fastened with an epoxy adhesive. 2 After allsurfaces have been wetted with liquid epoxy, a thickener isadded to the mix, and a generous helping is applied between

the dutchman and the sash. 3 Cut from the same species of wood as the sash, the dutchman should stand slightlyproud of the surrounding surfaces. After the epoxy hascured fully, the patch can be planed and sanded to make the repair invisible.

88 FINE HOMEBUILDING

fashioned of the same species of wood as thesash: first-growth, tight vertical grain, if pos-sible. I maintain a ready stock of raw mater-ial for replacement parts because I neverdiscard any old wood.

Whenever large-scale repairs are needed,the sash has to be disassembled. Early sashes(150 years old or more) were joined by a tapered wooden peg driven through a mor-tise and tenon. To disassemble this type offrame, the pegs must be punched out fromthe small-diameter side. Don’t worry aboutsaving the pegs; they can’t be reused. Sashesmade in later years substituted glue for pegs;they usually can be separated by cuttingthrough the glueline with a knife, then gen-tly tapping the mortised section loose using ablock of wood and a mallet.

After I’ve completed all necessary repairs,I reassemble the window sash using an exte-rior-grade carpenter’s glue such as TitebondII (Franklin International; 800-347-4583;www.titebond.com). Unlike an epoxy adhe-sive, carpenter’s glue is reversible, so it allowsfuture carpenters the opportunity to take thewindow apart should they ever need to makerepairs. If the joints are loose, however, I haveno choice but to use a thickened epoxy ad-hesive to fill the gaps.

During the gluing process, the frame issquared up, then clamped tightly and allowedto set for at least 24 hours. Afterward, all sur-faces are sanded thoroughly to prepare themfor paint: I use 60-grit paper to knock downthe high spots, followed by 100 grit to polisheverything paint-grade smooth.

Preservative and primer ensurethat the paint stays stuckOld wood presents a finishing challenge be-cause it tends to be extremely dry. If left un-treated, it will absorb the chemical bindersfrom primer, causing early paint failure. Toput some natural resins back into those driedwood fibers, I brush on a generous coating ofa homemade wood preservative, a mixture of50% mineral spirits and 50% boiled linseedoil (photo top left). I let the frame dry for 48hours before priming it, but I don’t use justany primer.

Traditional primers (oil or latex) soak intothe wood fibers to create a bond, but they can-not soak into the epoxy patches and thus areliable to fail. Instead, I apply a coat of B-I-N

primer-sealer (Zinsser Co. Inc.; 732-469-8100;www.zinsser.com) over all surfaces (photobottom left). This product is a white shellacdesigned to seal knotholes, among otherthings (see article pp. 60-63), but it forms astrong surface bond that adheres equally aswell to epoxy as to wood fibers.

Bed the glass in a bead of caulkPrior to reinstallation, I thoroughly clean allthe original glass. Then I apply a fine bead oflatex caulk to the shoulder that will receivethe glass (photo above). I “back-putty” theglass in caulk rather than glazing compoundbecause the supple caulk provides a cushionthat lessens the chance that the fragile, oldglass might shatter as I’m pressing it intoplace. After all the panes are bedded in thesash, a few glazier’s points are installed to se-cure the glass until the caulk has cured.

The glazing process requires finesse and asteady hand, both of which take practice to

1

After the repairs are done, the sashis treated with a generous coatingof a homemade wood preservative:one-half mineral spirits, one-halfboiled linseed oil. After two fulldays’ drying time, a shellac-baseprimer is applied. This combinationof ingredients ensures that the fin-ish coats of paint bond to a stable,uniform surface.

GLAZING TAKES PRACTICE

Old sashes needspecial attentionbefore painting

Homemade preservative

Shellac-base primer

FEBRUARY/MARCH 2004 89Photo bottom right: Courtesy of Allied Window Inc.

achieve (photos above). Glazing compounddoes not hold paint well until it has had a cou-ple of weeks to cure. If time allows, I store thesashes in my shop, then apply two full coatsof paint before I reinstall them. When paint-ing over the glazing compound, I’ve learnedthat it’s important to let the paint overlap theglass (about 1⁄16 in.); this overlap prevents water from getting behind the glazing, caus-ing early failure.

Repaired window sashes have a greater lifeexpectancy than new window units, but aswith anything that’s exposed to nature’swrath, they still have to be maintained. I urgeall my clients to open and close each of theirwindows at least once a year and to examinetheir windows thoroughly for signs of rot atleast every five years. �

David Gibney is a restoration contractorin Smithsburg, Md. Photos by TomO’Brien, except where noted.

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1 To prevent breakage, the author beds each paneof glass in a layer of acrylic latex caulk before he se-cures them with glazier’s points (one point per side isusually enough). 2 With the sash propped up on ahomemade easel, he works glazing compound into a

By today’s standards, old double-hungs are drafty; but thatproblem is easy to fix. The most straightforward solution isto add storm windows. Triple-track units are the most com-mon option, but they can be bulky and conspicuous. If youdecide to go this route, buy from a high-end manufacturerthat offers custom sizing and a wide choice of colors.

For a less conspicuous appearance, I prefer the HistoricOne-Light (HOL) unit from Allied Window Inc. (800-445-5411; www.alliedwindow.com). This low-profile storm (photoleft) is essentially a single-track unit in which upper andlower sashes mount one over the other; screens are avail-able, but they must be stored elsewhere. For restoration

purists who’d rather not see any storm window on the outside of a home, this man-ufacturer also offers a variety of interior storm-window options.

The windows themselves also can be tightened up. The edges of fixed sashesshould be caulked, inside and out, to eliminate air infiltration. If you’re willing toremove them from their frames, sashes and stops can be routed and retrofittedwith specially designed weatherstripping. Resource Conservation Technology Inc.(410-366-1146; www.conservationtechnology.com) offers a wide variety of weath-erstripping, as well as an excellent catalog that doubles as an installation manual.

Storm windows and weatherstripping tighten up old windows

3⁄8-in.-dia. rope before pressing it into place. 3 Afterlubricating a putty knife with boiled linseed oil, hetools the glazing compound using an index finger asa guide. Finally, he eliminates minor imperfections inthe glazing by wiping downward with a taping knife.