Double-pane and triple-pane insulated glass units (IGUs) dramatically reduce heat transfer -- keeping your home cool in DC summers and warm in Virginia winters. We install new IGUs and repair foggy window seals across the DMV.
An insulated glass unit (IGU) consists of two or more panes of glass separated by a spacer bar and sealed at the perimeter. The sealed gap between panes is filled with air or, more commonly in modern units, with argon gas. This gas-filled gap is the primary insulating layer -- it dramatically reduces heat transfer by convection and conduction compared to a single pane of glass.
The spacer bar that separates the panes contains a desiccant material that absorbs any residual moisture inside the sealed unit during manufacturing. This keeps the interior surfaces fog-free for the life of the seal. When you see condensation or fog between your window panes, it means the perimeter seal has failed and moisture-laden air has entered the gap.
For the DMV climate -- hot, humid summers and cold winters -- insulated glass is essential. A single-pane window has a U-factor of approximately 1.0, meaning it offers almost no resistance to heat flow. A standard double-pane IGU with air fill reduces that to approximately 0.47. Add Low-E coating and argon gas fill, and the U-factor drops to 0.28-0.30. Triple-pane with Low-E and argon reaches 0.18-0.22 -- nearly five times better insulation than a single pane.
Most windows in the DMV built after 1990 already have double-pane IGUs. If your windows are foggy, drafty, or the original single-pane glass, an IGU upgrade or replacement is one of the highest-ROI home improvements available.
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Condensation between window panes is the most common insulated glass problem in the DMV. It means the hermetic seal has broken, argon gas has escaped, and moisture has entered. The good news: we can replace just the glass unit without replacing your entire window.
Fog, haze, or milky appearance between panes that cannot be wiped away from either side. You may notice it worsens in direct sunlight or temperature changes. This is internal condensation -- proof of seal failure.
We remove the failed glass unit from your existing frame, order a new IGU to exact dimensions with your choice of Low-E, argon, and glass type, and install the replacement. Your frame, trim, and hardware stay in place.
The new IGU restores thermal insulation, eliminates the foggy appearance, and can improve performance beyond the original if you upgrade to Low-E and argon. Most IGU swaps are completed in 1-2 hours per window.
Double-hung, casement, sliding, and picture windows. IGU replacement is the most common residential glass service we perform in Northern Virginia and Maryland.
Large sliding glass doors with failed seals are a significant source of energy loss. We replace the IGU panels in standard and custom-size door frames.
Overhead IGUs with Low-E and laminated glass for code compliance. Skylight IGU replacement is a specialty service -- improper installation leads to leaks.
Storefront glazing with insulated units for energy code compliance. Large-format IGUs for retail, office, and restaurant applications across the DMV.
Multi-panel insulated glass systems for year-round comfort. We upgrade single-pane sunroom glazing to double-pane Low-E IGUs for dramatic temperature improvement.
Georgetown and Capitol Hill homes with original single-pane windows can receive custom IGU inserts that fit inside existing historic frames without altering the exterior appearance.
Fog between panes means the perimeter seal of the insulated glass unit (IGU) has failed. Moisture from the air enters the gap between the panes and condenses on the interior glass surfaces. Once a seal fails, the argon gas fill (if present) also escapes, reducing the window's insulating performance. The only fix is replacing the IGU -- the glass unit itself, not necessarily the entire window frame.
Yes. In most cases, we replace only the insulated glass unit (IGU) inside your existing window frame. This is called a glass-only replacement or IGU swap. It is significantly less expensive than a full window replacement, preserves your existing frames and trim, and can be completed in 1-2 hours per window. If the frame is damaged or rotted, we will recommend full replacement.
Argon is an inert, non-toxic gas that is denser than air. When used to fill the gap between panes in an IGU, it reduces heat transfer by convection more effectively than air alone. Argon-filled IGUs typically improve the U-factor by 10-15% compared to air-filled units. Given the modest cost difference, argon fill is almost always worth it for DMV homes where both heating and cooling costs are significant.
A quality insulated glass unit with a properly applied dual-seal system typically lasts 15-25 years before the perimeter seal begins to degrade. Factors that shorten seal life include direct sun exposure (south- and west-facing windows degrade faster), poor original installation, frame movement from settling, and repeated thermal cycling. When seals fail, the glass fogs -- that is the signal to replace the IGU.
Double-pane IGUs have two glass layers with one air/gas gap. Triple-pane IGUs have three glass layers with two gas gaps. Triple-pane provides about 20-30% better insulation (lower U-factor) than double-pane but weighs more, costs more, and requires heavier-duty hardware. For most DMV residential applications, double-pane with Low-E and argon delivers the best balance of performance and cost.
Absolutely. A failed IGU seal means the argon gas has escaped and moisture has entered. The insulating performance drops dramatically -- often to near-single-pane levels. Replacing the IGU with a new unit restores full thermal performance. If you upgrade to Low-E coated glass at the same time, you gain even more energy savings than the original window provided when new.
Add Low-E coating to your IGU for maximum energy savings
Safety glass required in code-mandated locations
Acoustic IGU configurations for noise reduction
Security and UV protection in an IGU assembly
Reduce glare and solar gain with tinted IGUs
Crystal-clear IGU without the green tint
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Foggy windows, drafty rooms, or new construction -- we provide free estimates for all insulated glass projects across DC, Maryland, and Northern Virginia.
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