Step 1: Inspect Weatherstripping on All Windows
Weatherstripping is the first line of defense against cold air infiltration. Over time, it compresses, cracks, hardens, and detaches -- all of which create gaps that allow cold air to enter and warm air to escape. Begin your winter preparation by inspecting the weatherstripping on every operable window in your home.
To test effectiveness, close and lock each window, then slowly run your hand around the edges of the sash. If you feel air movement, the weatherstripping has failed at that point. For a more precise test, close the window on a piece of paper. If the paper pulls out easily without tearing, the seal is insufficient. Focus on the meeting rail (where upper and lower sashes overlap on double-hung windows) and the sides of the sash where it contacts the frame.
Replacement weatherstripping is available in several types: adhesive-backed foam (easiest to install, lasts 1 to 3 years), V-strip or tension seal (durable, lasts 3 to 5 years), rubber or silicone tubular (excellent seal, lasts 5 or more years), and spring bronze (most durable, lasts 10 or more years). For the DC metro climate with its temperature extremes, invest in rubber, silicone, or spring bronze for the best long-term performance.
Step 2: Check Exterior and Interior Caulking
Caulking seals the gap between the window frame and the wall opening (the rough opening). Over time, caulk shrinks, cracks, and separates from one or both surfaces, creating a direct path for cold air to enter the wall cavity and reach the interior. Inspect the exterior caulk around every window by looking for visible cracks, gaps, missing sections, or areas where the caulk has pulled away from the frame or siding.
On the interior, check the trim around each window for gaps between the trim and the wall, and between the trim and the window frame. These gaps may indicate that the original caulking or insulation behind the trim has deteriorated. While interior gaps allow air infiltration, they are also a sign that the wall-to-frame connection needs attention.
Choosing the Right Caulk
For exterior window caulking in the DC metro area, use a high-quality polyurethane or modified silicone caulk rated for outdoor use and temperature extremes of -20 to 150 degrees Fahrenheit. Avoid pure silicone on painted surfaces (paint will not adhere to it) and avoid acrylic latex for exterior applications (it becomes brittle in freeze-thaw cycles). Apply caulk when temperatures are above 40 degrees and surfaces are dry. A clean, properly applied bead of exterior caulk should last 7 to 10 years.
Step 3: Test Window Operation and Locking Hardware
Every window in your home should open, close, and lock smoothly. A window that does not lock fully cannot compress the weatherstripping against the frame, creating air gaps even with new weatherstripping. Test every window lock to ensure it engages fully and pulls the sash tight against the frame. On double-hung windows, test both the sash locks and any tilt-latch mechanisms.
Casement windows (crank-operated) should close flush against the frame when the locking handle is engaged. If the sash does not pull tight, the operator mechanism or hinge may need adjustment. Sliding windows should glide smoothly in their tracks -- rough operation often indicates dirty tracks, worn rollers, or a bent frame. Clean tracks with a vacuum and brush, then lubricate with silicone spray (never oil-based lubricants, which attract dust and dirt).
Step 4: Inspect Storm Windows
Many older homes in the DC metro area, particularly in historic neighborhoods of Alexandria, Georgetown, Capitol Hill, and Takoma Park, have exterior storm windows. Storm windows provide an additional layer of insulation over the primary window and can reduce heat loss by 25 to 50 percent when properly maintained. Before winter, inspect each storm window for cracked or broken glass, deteriorated glazing putty, bent or corroded frames, and gaps between the storm window and the exterior casing.
For combination storm windows (storm and screen panels in a single track), switch from the screen panel to the storm glass panel in October. Ensure the glass panel seats fully in the track and the latch engages. Clean the weep holes at the bottom of the storm window frame -- these small holes allow moisture to drain and must remain clear to prevent water damage. If your storm windows are severely deteriorated, consider replacing them or upgrading to new primary windows that eliminate the need for storm windows entirely.
Step 5: Check for Condensation and Seal Failure
As temperatures drop, failed insulated glass seals become visible. Fog, moisture, or a milky haze between the panes of double or triple-pane windows indicates that the perimeter seal has failed, the insulating gas (argon or krypton) has escaped, and the desiccant inside the spacer bar is saturated. This reduces the insulating performance of the window by 10 to 15 percent.
Check every double-pane window in your home on a cold morning (when the temperature differential makes condensation most visible). Note which windows show interior fogging -- these are candidates for insulated glass unit (IGU) replacement or full window replacement, depending on the age and condition of the frame. Schedule these repairs before the coldest months to maximize energy savings during peak heating season.
Interior Surface Condensation
Moisture on the room-side glass surface is typically a humidity issue, not a window failure. It indicates that indoor humidity is high relative to the glass temperature. Reduce humidity with ventilation or a dehumidifier, and consider upgrading to higher-performance glass.
Between-Pane Condensation
Moisture trapped between the panes of an insulated glass unit is a definitive sign of seal failure. The IGU must be replaced -- there is no effective repair for a failed seal. This can be done without replacing the entire window in many cases.
Step 6: Add Window Insulation Film Where Needed
For single-pane windows or older double-pane windows that you are not ready to replace, interior window insulation film is a practical and affordable solution. Heat-shrink film kits cost $5 to $15 per window and create a sealed dead air space that adds approximately R-1 to the window assembly. This reduces heat loss through the glass by 20 to 30 percent and eliminates drafts at the glass surface.
Apply the film to the interior trim using double-sided tape, then shrink it tight with a hair dryer to remove wrinkles. The result is a nearly invisible barrier that significantly improves comfort near the window. The tradeoff is that the window cannot be opened until the film is removed in spring, and visibility is slightly reduced. For windows that you never open during winter (most of them), this is an excellent temporary improvement while planning for permanent window replacement.
Step 7: Inspect and Maintain Window Hardware
Window hardware -- locks, operators, hinges, balances, and tilt latches -- must function properly for windows to seal correctly against cold air. Lubricate all moving parts with a dry silicone lubricant or white lithium grease. Check sash balances (the springs or counterweights that hold window sashes up) and replace any that have failed, as an improperly balanced sash will not seat correctly in the frame.
For casement windows, inspect the operator arm and track for wear, corrosion, or bending. The operator must draw the sash tightly against the frame when closed. If the crank feels loose or the sash does not compress evenly against the weatherstripping, the operator may need adjustment or replacement. These are inexpensive repairs that significantly improve the thermal performance of the window.
Step 8: Schedule Repairs Before Cold Weather Hits
The most important step in winter window preparation is scheduling necessary repairs before temperatures drop. Glass companies in the DC metro area experience a surge in emergency calls once winter arrives -- broken windows from storms, failed seals causing visible fogging, and cracked glass from thermal stress. Wait times for service increase significantly from November through February.
If your inspection revealed cracked glass, failed seals, rotting frames, broken hardware, or windows that no longer close properly, schedule repairs in October or early November. This ensures your home is fully sealed before the first cold snap and avoids the premium pricing and longer lead times associated with emergency winter service calls. At Expert Glass Repair, we recommend scheduling a comprehensive window inspection every fall to identify and address issues proactively.
Emergency Contact for Winter Window Issues
If a window breaks or fails during winter, call (703) 679-7741 for emergency service. We provide temporary board-up and expedited replacement for broken windows throughout Northern Virginia, DC, and Maryland. Broken windows in winter are not just uncomfortable -- they can cause pipe freezing, water damage, and significant energy waste. Do not wait for warmer weather to address a broken or severely damaged window.
Energy Audit: The Professional Assessment
For homeowners who want a thorough, data-driven assessment of their window performance, a professional home energy audit is the gold standard. Energy auditors use blower door tests to measure overall air leakage, thermal imaging cameras to identify heat loss through windows and walls, and detailed calculations to quantify energy waste and prioritize improvements.
In the DC metro area, home energy audits are available through utility-sponsored programs (Dominion Energy, Pepco, BGE) often at reduced or no cost. The audit will identify which windows are the biggest energy losers and provide specific recommendations for repair or replacement. This data helps you prioritize your window improvement budget for maximum energy savings and comfort improvement.
Winter Window Preparation Checklist
Use this checklist to ensure your windows are fully prepared for the DC metro winter.
Inspect weatherstripping on all operable windows -- replace if compressed, cracked, or missing
Check exterior caulking around every window -- recaulk any gaps or cracks
Test all window locks and operators -- repair or replace failed hardware
Switch storm windows from screen to glass panels
Check for fog or condensation between double-pane glass -- schedule IGU replacement
Apply insulation film to single-pane or underperforming windows
Lubricate all window hardware with silicone lubricant
Inspect window frames for rot, cracks, or warping
Clean window tracks and weep holes to ensure proper drainage
Schedule professional repair for any issues found before temperatures drop
Frequently Asked Questions
When should I start preparing my windows for winter in the DC area?
Begin window winterization in early to mid-October in the DC metro area. This gives you time to inspect, repair, and weatherize before the first sustained cold arrives, typically in late November or early December. Scheduling professional repairs in October also avoids the rush of emergency calls that hits glass companies once temperatures drop. If you wait until December, you may face longer wait times and limited appointment availability.
Is window insulation film worth using?
Window insulation film is a cost-effective temporary solution for improving the thermal performance of single-pane or older double-pane windows. A properly applied shrink-fit film creates a dead air space that adds approximately R-1 to the window, reducing heat loss by 20 to 30 percent through that window. It costs $5 to $15 per window and takes 10 to 15 minutes to install. However, it reduces visibility, cannot be opened for ventilation, and must be reapplied each year. It is best used as a stopgap while planning window replacement.
How do I know if my window weatherstripping needs replacement?
Test weatherstripping by closing the window on a piece of paper or dollar bill. If the paper slides out easily, the weatherstripping is not creating an adequate seal. Also visually inspect for cracking, hardening, compression, gaps, or detachment. Foam weatherstripping typically lasts 1 to 3 years, rubber or silicone types last 3 to 5 years, and spring bronze lasts 10 or more years. If you feel drafts near closed windows, weatherstripping failure is the most likely cause.
Can I apply exterior caulking in cold weather?
Most exterior caulks require application temperatures above 40 degrees Fahrenheit for proper adhesion and curing. Below that temperature, caulk may not adhere, may cure improperly, or may crack as it dries. If you need to caulk in cold weather, use a polyurethane-based caulk rated for low-temperature application, or wait for a warmer day (the DC area frequently has 50-degree days even in November and early December). Apply caulk during the warmest part of the day and allow adequate cure time.
Should I replace windows in winter or wait until spring?
Window replacement can be performed year-round by experienced installers. Professional crews use techniques to minimize heat loss during installation, including working one window at a time and having the new window ready for immediate installation as the old one comes out. The exposure time per window is typically 15 to 30 minutes. The advantage of winter replacement is immediate energy savings and more available scheduling since spring and summer are peak demand seasons. Many homeowners find better appointment availability and potentially better pricing during the winter months.
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By the Expert Glass Repair Team
Serving the DMV since 2004 -- DC, Northern Virginia & Maryland
Expert Glass Repair helps homeowners throughout the Washington DC metro area prepare their windows for winter. From weatherstripping replacement to full window upgrades, we ensure your home stays warm and energy-efficient through the coldest months. Call (703) 679-7741 for a free winter window inspection.
Free Winter Window Inspection
Not sure if your windows are ready for winter? Our technicians will inspect your windows, identify problem areas, and recommend the most cost-effective solutions -- all at no cost. Backed by our Comprehensive Warranty.
Related services: Window Replacement | Window Repair