Preventing Window Condensation in Utah Winters: 7 Proven Methods

Window condensation during Utah winters is not inevitable. While our climate creates the perfect conditions for foggy, dripping windows — bitterly cold nights, dry outdoor air that tempts you to crank the humidifier, and homes sealed tight against the cold — there are proven methods that eliminate the problem without sacrificing comfort.

These seven methods are arranged from the easiest and cheapest to the most comprehensive. Most Utah homes need a combination of two or three to fully prevent condensation. Start at the top, implement each one, and stop when your windows stay dry.

Method 1: Calibrate Your Humidifier to Outdoor Temperatures

Cost: Free | Difficulty: Easy | Impact: High

This is the single most effective step for the majority of condensation-prone Utah homes, and it costs nothing.

Most furnace-mounted humidifiers have a fixed set point — typically 40-45% relative humidity. That is fine when outdoor temperatures are above 30 degrees F, but it is far too high during the cold snaps that define Utah winters. The colder it is outside, the colder your window glass becomes, and the less indoor moisture it takes to reach the dew point.

Use this temperature-based humidity chart:

• Above 30 degrees F outside: Up to 40% indoor humidity
• 20 to 30 degrees F outside: 35% maximum
• 10 to 20 degrees F outside: 30% maximum
• 0 to 10 degrees F outside: 25% maximum
• Below 0 degrees F outside: 20% maximum

To implement this, you need two things: a digital hygrometer placed in the room where condensation is worst ($15-30 at any hardware store) and a willingness to adjust your humidifier as the weather changes. During a typical Salt Lake City January, you might adjust your humidifier three or four times as temperatures fluctuate between cold snaps and milder periods.

If your humidifier is a standalone portable unit rather than furnace-mounted, the same principle applies. Many portable units have built-in humidistats that can be set to a target percentage. Set it to match the chart above based on the current outdoor temperature.

The adjustment does mean your indoor air will feel drier during the coldest weeks. Combat this with personal comfort measures — a glass of water on the nightstand, lip balm, and moisturizer — rather than by raising humidity back to levels that cause condensation. The tradeoff is dry air vs. wet windows, and wet windows lead to mold and wood damage that is far more costly than dry skin.

Method 2: Upgrade Kitchen and Bathroom Exhaust Ventilation

Cost: $100-$400 per fan installed | Difficulty: Moderate (DIY-able for replacements) | Impact: High

Kitchens and bathrooms are the biggest point-source moisture generators in any home. Every time you boil water, run the dishwasher, or take a shower, you are pumping significant moisture into the air. Proper exhaust ventilation removes that moisture before it reaches your windows.

The problem in many Utah homes: builder-grade exhaust fans are undersized, poorly ducted, or not vented to the exterior at all. Here is how to check and upgrade.

Bathroom fans: A standard bathroom needs a fan rated at 80-110 CFM (cubic feet per minute). Many homes built in the 1990s and 2000s have 50-CFM fans that cannot keep up with a hot shower. To test your current fan, hold a single sheet of toilet paper against the fan grille while it is running. If the fan cannot hold the paper, it is too weak.

Upgrade to a fan rated at 100+ CFM with a humidity-sensing switch. These switches detect rising humidity and automatically turn the fan on, then keep it running until humidity normalizes. This is far more effective than relying on remembering to flip a switch. Quality units from Panasonic, Broan, or Delta Breez run $80-200 for the fan plus $100-200 for installation if you hire an electrician.

Kitchen exhaust: Your range hood should exhaust to the exterior, not recirculate through a charcoal filter. Recirculating hoods remove grease and some odor but do not remove any moisture. If your range hood is a recirculating model, consider upgrading to a ducted model. If that is not practical, at minimum run it on high whenever you are boiling, steaming, or using the dishwasher, and run it for 10-15 minutes after cooking stops.

Verify exterior venting: Go outside and confirm that both bathroom and kitchen exhaust terminate through the wall or roof with a proper dampered vent cap. It is not uncommon to find exhaust ducts that terminate in the attic — which means you are pumping moisture into your attic space rather than outside. This causes both window condensation problems and attic mold issues.

Method 3: Improve Air Circulation at Window Surfaces

Cost: Free to $50 | Difficulty: Easy | Impact: Moderate

Stagnant air pockets near windows allow moisture to accumulate on the cold glass surface. Even a small amount of air movement raises the glass surface temperature slightly and carries moisture away before it condenses.

Open window treatments during the day. Heavy curtains and closed blinds trap a pocket of cold, still air against the glass. This air cools to the glass temperature and condenses readily. Opening curtains and raising blinds in the morning allows warm room air to circulate past the glass.

At night, leave a gap. If you close window treatments at night for privacy or additional insulation (which is a good practice), leave a 2-3 inch gap at the bottom. This allows convective air circulation — warm air rises along the window, cools, sinks, and exits through the gap at the bottom, to be replaced by more warm room air. This continuous loop keeps the glass surface slightly warmer.

Use ceiling fans. Set ceiling fans to run clockwise on low speed during winter. This pushes warm air that has risen to the ceiling back down toward the floor and windows. The gentle circulation prevents stagnant cold zones.

Reposition furniture. Bookcases, desks, couches, and other furniture placed against or directly below windows block air from reaching the glass. Move them at least 4-6 inches away from windows, especially during the heating season.

Direct a small fan at problem windows. For the one or two windows that condense worst, a small desk fan or clip-on fan directed at the glass can eliminate condensation entirely. This is not elegant, but it works while you implement longer-term solutions.

Method 4: Install a Heat Recovery Ventilator (HRV)

Cost: $2,000-$5,000 installed | Difficulty: Professional installation | Impact: Very High

An HRV is the gold-standard solution for homes that are tightly sealed and well-insulated — which describes most modern Utah construction and many retrofitted older homes. It addresses the root cause of elevated indoor humidity in tight homes: insufficient air exchange.

An HRV works by simultaneously exhausting stale, humid indoor air and bringing in fresh, dry outdoor air. The two airstreams pass through a heat exchanger core where the outgoing warm air transfers 70-85% of its heat to the incoming cold air. You get the moisture-reduction benefit of outdoor air exchange with only a fraction of the energy penalty.

During a Utah winter, incoming outdoor air at 10 degrees F and 30% relative humidity enters the HRV. As it is heated by the outgoing indoor air stream, its relative humidity drops dramatically. By the time it enters your home at near-room temperature, its relative humidity may be only 10-15%. This very dry incoming air dilutes and lowers your overall indoor humidity.

Best candidates for an HRV: Homes built after 2000 with tight construction, homes that have had air sealing or insulation retrofits, homes where humidity stays above 35% despite humidifier reduction, and homes where multiple occupants and daily activities generate more moisture than exhaust fans can handle.

HRV vs. ERV: An ERV (energy recovery ventilator) transfers both heat and moisture between the airstreams. In Utah's dry winter climate, an HRV is usually the better choice because you want to expel moisture, not retain it. An ERV makes more sense in humid summer climates.

A qualified HVAC contractor can assess your home's ventilation needs and specify the right size unit. Look for a contractor familiar with ASHRAE 62.2 ventilation standards.

Method 5: Apply Temporary Interior Window Insulation

Cost: $3-8 per window | Difficulty: Easy DIY | Impact: Moderate to High

Window insulation film kits — the heat-shrink plastic type you apply with double-sided tape and a hair dryer — are an underappreciated condensation solution. They work by creating an insulating air pocket between the plastic film and the glass, keeping the interior surface (now the film, not the glass) warmer.

Studies have shown these kits can reduce heat loss through windows by up to 50% and reduce condensation proportionally. For $50-100, you can insulate every window in a typical home and see results immediately.

Application tips for best results:

• Clean the window frame thoroughly with rubbing alcohol before applying the double-sided tape. Any dust or moisture will prevent the tape from adhering.
• Apply the film on a dry day when temperatures are moderate, if possible. The tape adheres best above 50 degrees F.
• Pull the film taut before shrinking with a hair dryer. Hold the dryer 2-3 inches from the film and move continuously — do not linger in one spot.
• Trim excess film neatly for the best appearance.

Limitations: The film is temporary (one season), somewhat visible, and prevents window operation. You cannot open a filmed window without removing the kit. It also does not address windows with failed IGU seals or structural issues — it just reduces the symptom.

For windows you rarely open during winter, this is an excellent cost-effective measure that buys time while you plan more permanent upgrades.

Method 6: Seal Air Leaks Around Window Frames

Cost: $10-50 per window (DIY) | Difficulty: Easy to Moderate | Impact: Moderate

Cold air leaking around the edges of your window frame creates cold spots where condensation forms — not on the glass, but on the frame, trim, and adjacent wall. These leaks also make your furnace work harder and contribute to uncomfortable drafts.

Weatherstripping: Check the weatherstripping on operable sashes by closing the window on a dollar bill and trying to pull it out. If the bill slides freely, the weatherstripping is not making adequate contact. Replace with new weatherstripping matched to your window type — foam tape for casements, V-strip or tubular for double-hung.

Caulking: Inspect the caulk joint between the window trim (casing) and the wall. Cracked, peeling, or missing caulk allows air infiltration. Remove old caulk, clean the joint, and apply a quality silicone or polyurethane caulk. Also check the exterior caulk around the window unit where it meets the siding.

Foam insulation in the frame gap: The space between the window frame and the rough opening in the wall should be filled with low-expansion foam insulation. In many homes — especially those from the 1990s — this gap was left empty or stuffed with fiberglass scraps, which settles and degrades over time. If you can remove the interior trim, inject low-expansion spray foam into the gap. Use low-expansion only — high-expansion foam can warp window frames and prevent proper operation.

Method 7: Replace Underperforming Windows

Cost: $500-$1,200 per window | Difficulty: Professional installation | Impact: Very High (Permanent)

When your windows are themselves the weakest link — single-pane glass, failed IGU seals, deteriorated frames, or aged-out builder-grade units — no amount of humidity management or ventilation will fully solve the condensation problem. Replacement is the permanent fix.

Modern energy-efficient windows specified for Utah's climate include dual-pane or triple-pane insulated glass with low-E coatings, argon or krypton gas fill between panes, warm-edge spacer bars that prevent condensation at the glass edges, vinyl or fiberglass frames that do not conduct cold, and factory-applied weatherstripping designed for thousands of operating cycles.

These windows keep the interior glass surface above 50 degrees F even when outdoor temperatures drop below zero. At that surface temperature, you can maintain 35-40% indoor humidity without seeing a single drop of condensation.

Replacement also brings benefits beyond condensation control: lower heating and cooling bills, reduced outdoor noise, improved home value, and better comfort overall. For homes with failed IGU seals, replacement is not optional — the seal cannot be repaired.

If full-house replacement is not in the budget, prioritize the worst offenders: windows with visible seal failure, the rooms where your family spends the most time, and north-facing windows that receive no solar warming.

Putting It All Together: Your Action Plan

Most Utah homes do not need all seven methods. Here is how to build your personalized plan:

Start here (everyone): Implement Methods 1, 2, and 3. These are free or low-cost and resolve condensation in the majority of homes. Give them two weeks during cold weather.

If condensation persists: Add Method 5 (window insulation kits) for the worst windows and Method 6 (air sealing) for any windows where you feel drafts. These moderate-cost steps handle most remaining cases.

If you still have problems: Your windows are likely underperforming. Get a professional assessment and plan for Method 7 (replacement) on the worst windows. In the meantime, Method 4 (HRV) provides whole-house humidity management that improves both condensation and indoor air quality.

For a complete diagnostic framework that helps you determine whether your condensation is a simple humidity issue or a sign of window failure, read the comprehensive condensation and mold guide. And if you have already discovered mold as a result of past condensation, address that first with the mold identification and removal guide.

Every Utah winter tests your windows. With the right combination of these seven methods, your windows can pass that test — staying clear, dry, and mold-free from the first October frost through the last April snow.