Get free estimates from qualified pros Get free quotes » Most experts agree that condensation or fogging inside of a double-pane window technically is not a fixable problem—at least not in the sense that your window can be restored to its original level of performance. Presently, there are two different ways to deal with condensation: either replace the window (you can usually replace only the glass unit and not the whole window) or hire a local company to drill holes in the outer pane, clean the windows from the inside and install one-way air vents to help prevent future condensation. If your condensation problems are in a sliding glass door or a window that is likely to have tempered glass (for example, if the window has more than 9 sq. ft. of glass area and is less than 18 inches above the floor), your only option is replacement. This is because it’s essentially impossible to drill tempered glass without breaking it. You should assume that all doors with double-pane glass areas large enough to fit a 3-inch sphere through them are made with tempered glass (or in some cases, laminated safety glass).
Double-pane windows, also called “insulated” or “thermal” windows, are made with two panels of glass sandwiched over a spacer and sealant, creating a space between the panes that is filled with air or with a gas, usually argon or krypton. It is this sealed space that gives the window most of it’s thermal performance. The spacer may also contain a desiccant material to help absorb and moisture in the air within the sealed space. Condensation in a thermal window typically indicates a failure of the seal between the glass panels and/or saturation of the desiccant.Because a breached seal allows fresh air and water vapor to enter the window space, a condensation problem simply becomes a function of nature. Condensation is also a sure sign that gas-filled windows are no longer so. And since there’s no way to re-seal an insulated window, replacement of the glass is the only option for restoring maximum thermal performance, in addition to solving the condensation problem. As mentioned, most glazing on insulated windows can be replaced as a unit, which saves you the expense and remodeling work of replacing the entire window, frame and all.
If your windows are still under warrantee, the first step is to contact the supplier or manufacturer, since replacement may be free. If the warrantee has expired, it’s still a good idea to consult with the manufacturer to discuss the recommended replacement options. Many local glass companies can also fabricate new window units in any size.While insulated window restoration companies may claim that their processes can restore most of your window’s thermal performance (in addition to eliminating condensation), these claims remain hotly disputed.The only way to rid a thermal window of condensation is by removing the moist air in between the panes and replacing it with dry air. And there’s a professional service based on this very technique. Thermal window restoration or repair companies come to your house and drill a small hole (3/8-inch or so) at one top and bottom corner of the affected window. They spray various liquid solutions onto the inside faces of the panes through the top hole and suck them out through the bottom hole.
Once the window is clean and dry, the holes are sealed with little vent plugs that allow air and water vapor to escape the window cavity but don’t let them back in.Will this process work for your windows? Or it might not. There are numerous consumer accounts in both directions. In any case, restoration companies commonly claim that their process costs 1/3 to 1/2 as much as glass replacement. And don’t even consider a service that doesn’t offer a money-back guarantee.Deciding Which Way to GoThis can be a tough call, and you should examine your options carefully. If you decide to try restoration and it doesn’t work, you won’t really devalue the window further, since it has already failed. On the other hand, if the restoration isn’t satisfactory and the company doesn’t make good, you’ll be out the cost of restoration and will still be faced with paying for new glass. Of course, if thermal performance is a high priority, replacement is clearly the best option.The standard in patio doors is two panes of glass, factory sealed around an insulating airspace.
The frames may be aluminum or wood. The style may be French doors on hinges or sliding doors on tracks. But aside from a stray baseball, every double-glazed door is vulnerable to the same fatal flaw: fogging.Fog on the outside or inside surfaces is only an occasional nuisance you can wipe away. But you can't clear moisture between panes, although it may change some with the weather. On humid days, it might cloud the entire panel, then on dry days almost disappear. But it never goes away for good. The problem is cosmetic, doesn't hinder door operation, or in most cases even reduce its energy efficiency very much. But it makes the door look dingy, and sometimes the fog is so dense you can't see through it.It's a cracked gasket -- a breach in the rubbery edging installed at the factory to seal the dead airspace between panes. It might rupture after many years of normal operation, or from one crash closing. It might crack because a broken wheel bounces the door along the track, or from temperature swings that expand and contract the gas sealed inside.
(Most fog problems occur on the sunstruck side of the house, where temperature swings are greatest.) Whatever the cause, once the seal is broken the formerly dead airspace comes to life. When it's muggy outside, it's muggy inside the double glazing, too.The one sure fix is to replace the glass panel. The drawback is the expense -- unless replacement is covered by warranty. Depending on door size, type, and condition, replacement materials and labor could run $400 or more. That may be worthwhile if you're repairing one of several panels in a top-line, wood-frame unit that cost $3,000. It's an iffier proposition with an entry-level aluminum slider. Then it's like replacing the blown engine in a car. You could make the investment and gain a working version of the same old model, or put the repair money toward a new car.But some contractors advertise that they can fix this problem on site for less than the cost of replacement. Sounds good, until you find out what their plan is. Sometimes, it's simply drilling holes that make the gasket leak everywhere.
This lets out the moisture, they say -- and it certainly will on a dry day. But guess what comes back through all those holes the next time it rains: moisture.Others say they'll shoot a desiccant (absorptive drying agent) into the space between panes, which also means drilling more holes. That will help temporarily -- long enough for the contractor to collect his money. But as engineers at Pella, a leading manufacturer, put it, "Desiccant material will attract and hold as much moisture as it is capable of, but will eventually become saturated. When that happens, fogging will occur."De-fogging doors seems to attract contractors who promise what they can't deliver. No one can duplicate the elaborate vacuum and sealing processes of a door factory at your house. But some companies offer a kind of in-between fix. Their solution starts the same way: drill another hole, "so the unit can expel moisture on its own," the company says. Then they add a small valve that opens when sunlight pressurizes the air between the panes, allowing moisture to escape.
When the valve closes, "the sealed unit no longer accumulates moisture and has recovered its dry air insulating properties." To restore a typical fogged door, Apex charges $300 per panel.The California-based, Glass Guru Co. (the nearest of their 32 franchises is in Columbus, Ohio), has a similar approach. After drilling into the airspace, the company says they "clean it, flush it with a drying agent, and then reseal it with our patent-pending micro vents."With the vent approach, there are only two possibilities. The vent valve can open once to expel moisture and then close for good. Or it can keep working, opening and closing when fog builds up again. Apex says "the valve keeps working." That amounts to a breathing window, not a factory-sealed window. To explore this option, you need to be clear about exactly what the de-fogging service is promising: no more fog and a warranty to remove it at no cost in case there is? Or some fog now and then as the vents open and close. New Owner Demolishes O.j. Simpson MansionDark meaning of bubble-gum Pumped Up Kicks is tough to chewHandshakes For All, Including Simpson, As Fung Ends Testimony