You notice it one morning: a haze between your window panes that won’t wipe away no matter how hard you try. Or maybe the room near that window is always cold, even when the heat is running. Both of those symptoms point to the same culprit — a failed insulated glass unit, or IGU.
At Martin Glass, we’ve been replacing IGUs for Portland-area homeowners for over 25 years. We hear the same question constantly: “Do I need a whole new window, or just the glass?” The answer, more often than not, is just the glass — and that saves you real money. This guide explains exactly what an IGU is, how to tell when it’s failing, and what replacement realistically costs in the Portland metro area.
What Is an IGU (Insulated Glass Unit)?
An IGU is the sealed glass assembly inside your window frame. It’s not a single pane of glass — it’s two (or sometimes three) panes held apart by a spacer, with an airtight seal around the edges. That sealed cavity is filled with either air or an inert gas like argon or krypton, which acts as insulation.
This sandwich structure is what gives modern windows their energy efficiency. The gas fill slows heat transfer. Many IGUs also have a microscopic Low-E coating on one of the inner surfaces that reflects infrared heat while letting visible light through.
The frame — wood, vinyl, aluminum, or fiberglass — holds the IGU in place. When the IGU fails, the frame is usually still fine. A glazier can remove the old unit and drop in a new one without touching the frame. That’s why IGU-only replacement is almost always the smarter, cheaper move compared to full window replacement.
How to Tell Your IGU Has Failed
IGU seals don’t fail overnight. They degrade over time from UV exposure, thermal cycling (the glass expanding and contracting with temperature changes), and moisture. Here’s what failure looks like:
- Fogging or condensation between the panes — the most common sign. Once the seal breaks, moist air enters the cavity and condenses on the inner glass surfaces. You can’t clean it off because it’s on the inside.
- Visible streaks or mineral deposits between the panes — moisture that’s been evaporating and leaving residue behind.
- Drafts near a window that used to be tight — a failed seal means the insulating gas has escaped. The window is now performing like a single pane.
- Higher heating or cooling bills — this one is harder to pin on a single window, but multiple failed IGUs in a home add up fast on an energy bill.
- Ice forming on the interior glass surface in winter — in the Pacific Northwest climate, this is a clear sign the thermal barrier is gone.
If you’re seeing any of these in your Hillsboro or Beaverton home, the IGU is the first place to look.
IGU Replacement Cost: What Portland Homeowners Actually Pay
Pricing depends on several variables: glass size, glass type (standard clear, Low-E, tempered, or obscure), gas fill, and labor. According to data from HomeGuide and Angi, professional double-pane IGU replacement typically runs $150 to $400 per unit for most standard residential windows. Portland-area labor rates run roughly 10% above the national average, so factor that into any estimate.
| IGU Type | Typical Cost Range | Notes |
|---|---|---|
| Standard double-pane (clear glass) | $150 – $250 | Most common residential replacement |
| Double-pane with Low-E coating + argon | $200 – $350 | Best energy performance for Oregon climate |
| Tempered or safety glass IGU | $250 – $400+ | Required in doors, sidelites, bathrooms |
| Triple-pane IGU | $300 – $500+ | Premium insulation; less common in residential replacements |
| Obscure or decorative glass IGU | $200 – $400 | Bathroom windows, privacy panels |
Ranges sourced from HomeGuide and Angi national data; Portland area pricing may be 5–10% higher due to regional labor rates.
What Affects the Price Most
- Size — IGUs are priced per square foot of glass. A small bedroom window costs less than a large picture window or a sliding patio door panel.
- Glass specification — Low-E coatings and argon fill add cost but pay back in energy savings. Oregon’s climate — mild but cloudy and damp — makes Low-E a smart investment.
- Tempered vs. annealed — Any IGU in a hazardous location (within 18 inches of a door, near a floor, in a wet area) requires tempered glass by code. Tempered costs more to manufacture.
- Accessibility — A first-floor window costs less to service than a second-story unit that requires ladder work or staging.
- Number of units — Replacing multiple IGUs in one visit typically lowers the per-unit cost because the trip charge and setup time are shared across more work.
IGU Replacement vs. Full Window Replacement
This is the question every homeowner asks, and the answer matters for your budget. Full window replacement — frame and all — typically runs $300 to $1,000+ per window installed, according to Angi’s 2026 data. That’s two to four times the cost of IGU-only replacement for a standard window.
IGU-only replacement makes sense when:
- The frame is structurally sound — no rot, no warping, no damage to the sill or jamb
- The window still operates correctly (opens, closes, locks)
- The failure is limited to the glass seal, not the frame or hardware
Full window replacement makes sense when:
- The frame has wood rot or significant damage
- The window is an older single-pane unit with no IGU at all
- You’re doing a planned renovation and want to upgrade the style or operability
- Multiple windows in a home are failing simultaneously and a full replacement project makes economic sense
A qualified glazier can tell you which category you’re in after a quick look. We do this assessment for homeowners across Portland, Aloha, and Forest Grove every week.
Get Your Exact Price
Every window is different. Size, glass type, frame condition, and location all affect the final number. The fastest way to know what you’re looking at is to use our free online estimator — no phone call required, no obligation.
Price My Project — Free Online Estimator
Or call us directly. We’re local, we’re fast, and we carry IGU stock for most standard sizes — which means we can often turn a same-week appointment into a same-week repair.
Martin Glass: (971) 257-4946
Why a Local Glazier Beats a Big-Box Window Company
National window replacement companies make their money selling full window replacements. Their salespeople are not going to walk into your Hillsboro home and tell you that a $200 IGU swap will solve your problem. A local glazier’s incentive is different — we want the work we can do well, and we want you to call us again in ten years.
Martin Glass has been serving the Portland metro area for over 25 years as a family-owned glazing company. We know Oregon’s building codes, we know which glass specs perform in the Pacific Northwest climate, and we stock the most common IGU sizes locally so we’re not waiting on a two-week factory order.
When you call us, you’re talking to a glazier — not a call center.
Frequently Asked Questions
How long does an IGU last before it needs replacement?
Most IGUs last 15 to 25 years under normal conditions. The seal life depends on installation quality, sun exposure, and how much the window is exposed to thermal cycling. South- and west-facing windows typically fail sooner because they absorb more UV and heat. If your home was built or had windows installed in the early 2000s or before, some of your IGUs may be approaching end of life.
Can a foggy IGU be repaired, or does it have to be replaced?
Once an IGU seal has failed and fogging appears, the unit cannot be repaired — it must be replaced. There are services that drill small holes to inject desiccant and temporarily clear the fog, but this does not restore the seal or the insulating gas fill, and the fog typically returns. A new IGU is the only permanent fix.
Does homeowner’s insurance cover IGU replacement?
Standard homeowner’s insurance covers sudden, accidental damage — like a rock thrown by a lawnmower or a break-in. It does not cover gradual seal failure from age and wear, which is considered normal maintenance. If your IGU failed due to a covered event (storm damage, vandalism, impact), document the cause and contact your insurer before scheduling repairs.
How long does IGU replacement take?
For most standard residential windows, the swap itself takes 30 to 60 minutes per unit once the glazier is on site. We measure first, order or pull from stock, then schedule the install. For common sizes, we can often complete the full job — measure, order, install — within a week. Specialty sizes or custom shapes take longer due to fabrication time.
Do I need to be home while the IGU is replaced?
For exterior-accessible windows, you don’t always need to be present during the installation itself — but someone should be available for the initial assessment so we can check the frame condition and confirm measurements. We’ll walk you through the process before we start so there are no surprises.