Original windows are a big part of what gives an old home its charm, but when the sash cord dries out and breaks, you've got a heavy problem on your hands. Learn about your three main options for repairing a broken window sash cord.
LESLIE: Well, one focal point of any old home  is, of course, the windows . You know, they’re big, beautiful and also heavy. And they rely on a system of counterweights to help you raise and lower them.
TOM: And just like anything else with an old house, occasionally the cords supporting those weights can break and you’re left to resort to the old stick-in-the-window method to hold it up. But it doesn’t have to be that way. Tom Silva , the general contractor from TV’s This Old House , is here with the fix that will allow you to toss the window stick away once and for all.
TOM SILVA: Well, thanks, guys. It’s nice to be here.
TOM: And window construction has changed dramatically from the old days. So, tell us about how windows used to work and how they still do today if you’ve got an old home with its original windows .
TOM SILVA: Right. Well, windows work on a balancing system. Inside the weight cavities – in other words, behind the casing – there are four weights, two on each side.
TOM: And this is to the left and the right of the window: basically, the wall kind of right alongside of it.
TOM SILVA: Right.
TOM SILVA: So in each cavity, if you have a double-hung window , there will be two on each side. If you have a single-hung window, there’ll be one on each side. A single-hung window only opens in the bottom. A double-hung window opens top and bottom.
Well, what happens is the weight is held into place to the window with a rope. And over time, that ropes dries out and breaks and then you’ve got to replace it.
TOM: And that’s when you have the window that doesn’t really stay up. It feels very heavy. It can get dangerous.
TOM SILVA: Very heavy, yeah. Well, you’ve got to pull a window that weighs – depending on the size of it, it could weigh 5 pounds, it could weigh 25 pounds.
And there’s a few ways that you can repair that. You can replace that sash cord with another rope, you can replace it with a sash or you can replace it with a retractable balancing system.
TOM SILVA: And the rope is probably the most common.
TOM: And so, for that, you’re basically going to take your casing off to expose where that rope broke and kind of rethread it?
TOM SILVA: Well, actually, you don’t have to take the casing off.
TOM SILVA: You’re going to take off what is called the “stop bead.” The stop bead holds the sash into the opening. You need to take the stop bead off and if you live in an old house, it’s usually three or four screws. You take the screws off, you push the window up enough to get it out of the opening and then you’ll see there’s a little door on the left and the right side, held into place with one screw. You loosen the screw and the little door comes out, drops down or could – picks up, depending on how the company made them. You get that out of the way, you can reach in and pull the window weight out.
Now, you want to make sure that you untie the rope that’s there. And now you have to snake down a new rope from above to reattach it to that window weight.
TOM: So, that’s interesting. So even way back then, the manufacturers designed a way to replace that rope if it was necessary.
TOM SILVA: Absolutely. Because they knew it was going to wear out.
And then you just want to make sure that you attach the rope at the right dimension. You want to get the rope the right length so when you open the window, the weight isn’t touching the bottom.
TOM: Doesn’t bottom out.
TOM SILVA: Right. Exact.
TOM: Yeah. Got it.
TOM SILVA: So, once you’ve figured all that out, you put the window back into place. Now, you can use the rope or you can use a chain. A lot of people like to use the chain because they feel that once they do the chain, it’s not going to fall apart or rot.
LESLIE: Do you feel any sort of difference in how the window operates, between the rope and the chain?
TOM SILVA: The window with the chain is noisier when you open and close it. But it’s opening once and closing once, so it’s not like it’s up and down and going to keep you up all night.
TOM: Yeah. Now, if you didn’t want to go through the process of replacing the rope with a chain, are there ways to sort of replace jambs? I remember seeing, I guess what I’ll call sort of a “pressure jamb,” where it kind of squeezes the sides of the window. You pull the sash out, you put these new jambs in and slip the whole thing back in so that it’s sort of spring-loaded and holds the window in place.
TOM SILVA: Right. Well, they have what is called a “spiral balancing system.” And then, basically, they go into an aluminum or a vinyl track. But there is absolutely no insulation value to those except they basically are the balancing system. You attach them to the underside of the window. You have to put them in place before you put them in the window. You hold them together; you have to be a little bit of a contortionist. You put it into the opening, tilt it up and then the window is balanced.
The way you adjust the balance of the window is the tension on the stop bead when you put it in. So, in other words, when you let the window go, if it pops up, you have to take the stop bead and push it a little bit tighter to the window so that it moves the way you want it to move.
TOM SILVA: So it’ll stay where you put it, basically.
TOM: But it’s …
LESLIE: That’s really a trial-and-error sort of system.
TOM SILVA: Yeah. It’s not that difficult. It sounds a little tricky but it’s basically just applying pressure to the stop bead.
TOM: It sounds like it’s almost as much work as just redoing it the way the manufacturer intended for the window to work.
TOM SILVA: Right. The benefit to using a spiral balancing system is that it now allows you to insulate the cavity that the weights and pulleys were in. And by insulating the cavity of the weights and pulleys, you increase the efficiency of the window without doing anything to the window. Because that’s usually where your biggest heat loss is: in the cavity that holds the weights and pulleys.
LESLIE: Mm-hmm. So you probably do this a lot when you’re doing the repairs on This Old House, because you want to keep the authentic window to keep the historical aspect of the home in those situations. But you also want to boost the insulative value.
TOM SILVA: I do want to increase the insulation variable. What I do on an old house – I like the weights and pulleys. I love the old windows . But I then have to figure out a way to insulate behind that cavity. And lots of times, what I do is I insulate with a polyisocyanurate rigid-foam foil-faced and basically 1 inch or a ½-inch thick. And I just remove the casing because I now have the thickness of the plaster which is, in most cases, ¾ to 1 inch. So I can then sandwich tightly, in between the plaster and the casing, a piece of isocyanurate foam and I put my casing back on. I now have a window that is much more efficient.
You still get the draft that comes out of the pulley, where the rope goes, but it makes a huge difference in the window. And then I just spray-foam underneath the apron and over the header.
TOM: So it doesn’t matter if the window is old or new, there is a way to improve its efficiency.
TOM SILVA: Absolutely.
TOM: And that’s how you do it. Tom Silva, the general contractor on TV’s This Old House, thanks so much for stopping by The Money Pit.
TOM SILVA: It’s my pleasure. Thank you.
LESLIE: Alright. Catch the current season of This Old House and Ask This Old House on PBS. For local listings and step-by-step videos of many common home improvement projects, visit ThisOldHouse.com .
TOM: And This Old House is brought to you by Lumber Liquidators. Lumber Liquidators, hardwood floors for less.