You notice it on a cold morning: a foggy, hazy film between the panes of your double-pane window that won’t wipe away no matter what you do. That’s not a dirty window — it’s a failed seal. The insulated glass unit (IGU) has lost its argon gas fill and allowed moisture to creep between the panes. In the Portland area, where we get significant temperature swings and consistent rain, seal failure is one of the most common calls we take at Tualatin Valley Glass.
The good news: in most cases you don’t need to replace the entire window. You just need a new IGU installed into the existing frame. This guide explains exactly what that costs, what drives price differences, and how to make the right call for your home.
What Is an IGU and Why Does It Fail?
An insulated glass unit is the sealed glass assembly inside your window frame — two (or three) panes of glass with a spacer bar around the edge, filled with argon or krypton gas for insulation. The seal around that assembly keeps moisture out and the gas in.
Over time, that seal breaks down. Heat cycles expand and contract the frame. UV exposure degrades the sealant. Water infiltrates around the spacer bar. Once the seal fails, moisture gets trapped between the panes and you see that foggy, streaked, or condensation-filled look that won’t go away.
In the Portland metro climate — wet winters, warm summers — this process tends to accelerate. Homes in Tigard, Lake Oswego, and Tualatin frequently see seal failures on south- and west-facing windows first, since those exposures get the most sun stress.
Foggy Window Repair Cost: What Portland Homeowners Actually Pay
According to data from Angi and HomeGuide, IGU replacement typically runs $150 to $500 per window for most residential applications in the Portland area. That range covers labor and materials for a standard double-pane unit in a wood, vinyl, or aluminum frame.
Here’s how costs break down by the factors that matter most:
| Factor | Lower End | Higher End |
|---|---|---|
| Standard double-pane IGU (clear glass) | $150 | $280 |
| Double-pane with Low-E coating + argon fill | $220 | $380 |
| Triple-pane IGU replacement | $300 | $500+ |
| Oversized or specialty glass unit | $400 | $700+ |
| Hard-to-access window (2nd floor, ladder required) | Add $75 | Add $150 |
Price ranges sourced from Angi (2026), HomeGuide (2026), and HomeAdvisor (2025). Portland area costs may vary based on glass specs and site conditions.
What Drives the Price Up or Down
Glass Type and Coatings
The IGU itself is the biggest cost variable. Standard clear double-pane glass is the least expensive. If your existing windows have Low-E coatings (a thin metallic layer that reflects heat), the replacement unit needs to match — and that adds cost. Homes with energy-efficient windows often have Low-E glass, and matching it matters both for performance and appearance.
Window Size
Glass is priced by square foot. A small bathroom window costs significantly less than a large picture window or a wide sliding door glass panel. Large custom sizes sometimes require special ordering, which adds both cost and lead time.
Number of Windows
Most glaziers — including our team at Tualatin Valley Glass — offer better per-unit pricing when you’re doing multiple windows in one visit. If you have four or five foggy windows, getting them done together is almost always more cost-effective than scheduling separate appointments.
Frame Condition
IGU replacement assumes the frame is in good shape. If the frame is rotted, cracked, or badly out of square, the frame may need repair or full replacement — which changes the scope of the job entirely.
Access Difficulty
Ground-floor windows are straightforward. Second-story windows that require ladder work, or windows blocked by landscaping or decks, add labor time. Expect an additional $75–$150 for windows that require special access.
IGU Replacement vs. Full Window Replacement: Which Makes Sense?
This is the question we hear most often. Here’s the straight answer: if the frame is in good condition and the window hardware works properly, IGU replacement is almost always the better financial decision. You’re paying $150–$500 versus $300–$1,500 or more for a full window replacement — and you get the same result: a clear, insulated, moisture-free pane.
Full window replacement makes sense when:
- The frame is rotted, warped, or structurally compromised
- The window is single-pane and you want to upgrade to double-pane for energy savings
- The window hardware (locks, operators, tilt mechanism) is failing
- You’re renovating and want new profiles for aesthetic consistency
If none of those apply, save the money. A new IGU in your existing frame does the job.
What About Window Defogging Services?
You may have seen ads for “window defogging” — a process where a technician drills small holes in the glass, injects a cleaning solution, and reseals the holes. According to Angi, this runs $75–$200 per window, making it cheaper than IGU replacement.
Here’s our honest take: defogging can temporarily improve clarity, but it does not restore the insulating gas fill or the original seal integrity. The energy performance of the window is permanently compromised once the seal fails. Defogging is a cosmetic fix, not a structural one. For most Portland homeowners trying to maintain comfortable, energy-efficient homes, IGU replacement is the better long-term investment.
The Tualatin Valley Glass Advantage: 25+ Years of Local Experience
We’ve been replacing IGUs for homeowners across the Portland metro area — Tigard, Lake Oswego, Sherwood, Tualatin, and surrounding communities — for over 25 years. As a local, family-owned glazing company, we stock common glass sizes, which means faster turnaround on most standard jobs. We can also custom-order specialty glass, match existing Low-E specs, and source glass for older or uncommon window brands.
We show up, measure, order what’s needed, and install it right. No subcontractors, no upsells, no pressure.
Get Your Exact Price
The ranges above are a useful starting point, but your actual cost depends on your specific window dimensions, glass specs, and location. The fastest way to get a real number is to use our free online estimator — no obligation, no phone call required to start.
Get your free estimate at tualatinvalleyglass.com/price-my-project/
Rather talk to someone? Call us directly at (503) 639-4304. We serve Tigard, Portland, Lake Oswego, Tualatin, Sherwood, and throughout the Portland metro area. Most IGU replacements can be scheduled within a week, and same-week appointments are often available for straightforward jobs.
Frequently Asked Questions
How do I know if my window needs an IGU replacement or a full window replacement?
If the fogginess is between the panes and the frame itself is solid — no rot, no warping, and the hardware still works — you almost certainly just need a new IGU. A glazier can confirm this on a quick inspection. Full replacement is only necessary when the frame or operating hardware is failing, not just the glass seal.
How long does IGU replacement take?
The glass typically needs to be measured and ordered first, which takes 3–7 business days for most standard sizes. The installation itself usually takes 30–60 minutes per window once the glass arrives. Some common sizes can be done same-day or next-day from shop stock.
Will replacing the IGU improve my energy bills?
Yes. A failed window seal means the insulating argon gas has escaped and the thermal barrier between panes is gone — your window is essentially performing like a single pane. Replacing the IGU restores the original energy performance, which in Oregon’s climate translates to measurable heating and cooling savings.
Can foggy windows be repaired instead of replaced?
Defogging services exist and cost less upfront ($75–$200), but they are a cosmetic fix only — they do not restore the seal or the insulating gas. The fog may return, and the energy performance of the window remains degraded. IGU replacement is the only repair that fully restores the window’s function.
Does homeowner’s insurance cover foggy window repair?
Standard homeowner’s insurance generally does not cover IGU seal failure because it is considered normal wear and tear, not sudden damage. However, if the seal failure was caused by a covered event — a hail strike, impact from a storm — there may be a claim worth pursuing. Check your policy or ask your agent.
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