Help! My Windows Are Leaking

As a warranty manager for high end builders in the north Texas area for 20 years I was used to the frequent calls from new homeowners who would experience condensation, often heavy amounts, on the inside of their new thermal insulated glass windows. "What's going on here?" they often demanded to know. "I paid several hundred thousand dollars for this home from what I thought was a reputable builder and you give me low quality windows?" For first time homeowners who have just made such a major purchase this was a legitimate concern for someone who previously rented their dwelling and assumed this issue was a factor of "cheap" windows used by their landlord.

This excessive water build up on interior glass surfaces is the result of a natural condensation phenomena, often referred as the "tea glass" syndrome and can occur on well constructed and properly installed windows to some degree. When a cold surface suddenly experiences significantly warmer air running across it, this action condensates the moisture of that warmer air and makes the object "sweat". In the case of your windows on intense cold days the inner panel of your double pane, thermal insulated glass develops a colder temperature than the room air temperature and Voila!Condensation.

Product and Installation Defects

A defective window from the manufacturer or improper installation by the builder can increase the probability of condensation. Glass panels are glazed at the manufacturer's plant. They are then laid within the metal frame of the window on a bead of silicone to create an air tight seal. If this sealant bead is not dispensed adequately and equally along the window frame, air pockets can occur and allow air to pass through at these points. Some manufacturers have had quality control issues too where proper applications of sealant have prevented a strong bonding affect, leaving the glass loose in it's framed opening. This can be detected by moderately pushing against the glass near the metal frame on the opposite side where glazing bead is installed. If not properly bonded you will see the glass push away from the frame. On newer homes your builder's warranty or the window manufacturer's warranty will correct this defect.

Builders today have to meet certain local codes that insure air tightness around windows, doors, pipes and other products that create a break or penetrate your home's vapor barrier. But older homes may not have been built with this up-grade requirement. So minimal water-intrusion techniques could be a factor with the condensation on your windows if your home is over 5-6 years old. Water proof flashing membranes like FortiFlash are now installed over all window edges attached to the framing before siding or brick go up. For tighter seals at likely air gaps, expansive aerosol foams are used to fill such areas as a part of the home's insulation package.

Practices to Reduce Condensation

Some rooms develop higher rates of condensation than others. Obviously rooms like kitchens, bathrooms and laundry rooms where warm moisture is generated at sinks, showers and washer/dryer units will experience greater degrees of moisture build up, effecting condensation. To minimize this effect, always leave doors open where you can and run vent fans in these room where you have them to remove warm vapor that contributes to condensation.

Moisture build up from condensation is primarily a threat if you allow it to remain on organic materials long enough. Most of what your home is built from comes from organic material like wood and gypsum. As you detect it, dry it quickly with towels and run fans to circulate the air to eliminate this main source for mold and mildew.

Older homes are not built as air tight as newer models are (as noted above) and this has the disadvantage of allowing cold air to be drawn in through the tiniest of exterior wall and ceiling cavities. This cooler air drawn in from the outside will then interact with the warmer surfaces conducive to condensation like glass and solid surfaces around windows and doors such as tile and marble. Keep your window and door openings caulked on the exterior. The effects of soil settlement and the expansive reactions to hot and cold climates over time will create gaps at these points and allow greater opportunity for condensation to occur.

Mold can also develop behind walls around windows and doors because the moisture that these gaps allow in are undetectable to you until you see the residual effects of mold - a green, black or beige discoloration on the organic materials there like sheet rock. If you suspect air leaks that can contribute to mold or see the tell-tale signs of condensation, place a small fan in that area and face it at the wall to offset the temperature variations and draw moisture from out behind the sheet rock surfaces. It takes sheet rock about 24 hours when constantly wet to create a viable environment for mold to develop. Therefore, detecting the source of a leak, repairing it quickly and further depriving this organic food material any moisture will stifle the incubation process that allows mold and mildew to occur.

HVAC Systems

Though it will not prevent it under all circumstances, newer, advanced HVAC systems that properly vent and balance room pressure in your home can help reduce the effects of condensation. Humidity is a source of moisture. High humidity levels will generate the moisture required for condensation. A good HVAC system will remove the humidity that can occur in homes by circulating the air in your home through a system of ducts that essentially replace more humid room air with dryer air. The relative humidity ratings in our homes should not exceed much past ASHRAE recommendations of 55%.

Maintaining these lower relative humidity levels will also lessen the risk of mold formations inside living areas.According to a 2007 Florida Solar Energy Center study "The vast majority of mold species require "water activity" levels that are equivalent to material equilibrium moisture contents corresponding to relative humidities of at least 70%. In fact, the great majority of serious, large mold outbreaks inside buildings occur where porous, cellulose-type materials have literally been kept wet by liquid water or sustained condensation. Human beings prefer humidities that are below the critical relative humidity for mold growth."

Homeowner Maintenance

Moisture intrusion is a homeowner's worst enemy. The primary sources at roofs, windows and plumbing lines are the more familiar sources of water leaks. The degree to which moisture accumulates though through condensation and poor air circulation within a home are secondary factors that many homeowners never consider, yet can be easily controlled. The life of your home and thus its long-term value depends on routine homeowner maintenance.

Unlike many hi-tech purchases in the market today the home is perhaps the last major consumer expense that is handmade. New technology and design have reduced the homeowner's need for maintenance from only a decade ago, Regardless though, mankind's age old battle with moisture still requires a physical effort by homeowners to prevent water damage that will seriously devalue a home's worth and incur unwanted expenses. An annual physical inspection of likely spots where water intrusion can occur will go along way to accomplish this.