How do I know if my window has a failed seal versus dirty glass?

The test is simple: wipe the glass surface on both the interior and exterior. If the haze or fog is still present after wiping both surfaces, it is between the panes -- a failed IGU seal. If the glass clears when wiped from one side, it is surface contamination that cleaning resolves. Failed IGU fog often has a particular quality: it may be heavier in the morning after cool nights and lighter in the afternoon when temperatures equalize, because condensation responds to temperature differential. Mineral staining from years of condensation between the panes appears as a white haze or streaking that does not respond to temperature changes.

How long do double-pane windows last in Tampa Bay before the seal fails?

Double-pane window IGUs installed in Tampa Bay homes typically last 15 to 25 years before seal failure becomes visible, with considerable variation based on sun exposure, installation quality, and original manufacturing. South and west-facing windows -- which experience the most daily thermal cycling from direct afternoon sun -- tend to fail earlier than north or east-facing windows in the same home. Windows over HVAC supply registers or near heat-generating appliances also cycle more and fail faster. Quality of the original spacer and sealant materials matters: windows from the early 1990s sometimes used organic sealer compounds that degraded faster than modern polymer sealants.

Does a failed window seal affect a Tampa Bay home's energy bill?

Yes, measurably. An intact double-pane IGU provides thermal insulation from both the trapped gas fill and the dead air space between the panes. A failed seal that has been infiltrated by ambient humid air loses some of that thermal barrier. In Tampa Bay's climate where cooling load is the primary energy cost, south and west-facing windows with failed seals allow more solar heat gain into the home than intact units. The energy difference per window is not dramatic -- a single failed window is unlikely to produce a noticeable change in your power bill -- but multiple failed windows on solar-exposed elevations can add meaningfully to cooling load. Impact-rated or low-E glass replacement windows address both the seal failure and the solar heat gain simultaneously.

Do home inspectors always flag window seal failures?

Yes. Window seal failure is a standard item in a home inspection report. Inspectors note the number and location of failed IGUs as a material defect. Buyers receive this information and typically use it to negotiate either a price reduction or a credit for window repair or replacement. Sellers who address IGU failures before listing eliminate this inspection finding and the negotiating leverage it creates. IGU-only replacement (just the glass unit, not the frame) is typically the most economical way to clear this finding before listing. Call (813) 416-8676 to discuss window assessment and the referrals for IGU or window replacement work in your area.

Window Seal Failure in Tampa Bay: What the Fog Means and What to Do About It

What Is Window Seal Failure?

Most windows in Tampa Bay homes built since the 1990s are insulated glass units -- two panes of glass sealed at the edges with a perimeter spacer and sealant, with the cavity between the panes filled with argon gas or dry air. This sealed unit is called an IGU (insulated glass unit). The sealant at the perimeter of the unit keeps the cavity sealed against moisture infiltration from outside.

When the sealant fails -- from age, thermal stress, or manufacturing defects -- outside humid air enters the space between the panes. In Tampa Bay's humid climate, that infiltrating air carries moisture that condenses on the interior glass surfaces when temperatures drop slightly. The result is the fogged, hazy, or streaked appearance that homeowners notice: it is not on the exterior surface (wiping it does nothing), and it cannot be cleaned because it is between the panes. This is a failed IGU.

James Evans and the Best Bay Services team see window seal failure regularly in Tampa Bay homes, particularly on south and west-facing windows that experience the most thermal cycling. This guide explains why Florida accelerates IGU failure, what the realistic fix options are, and where this repair fits in the handyman-versus-specialist question.

Why Florida's Climate Accelerates Window Seal Failure

IGU seal failure is a lifespan issue -- all sealed units eventually fail. But Tampa Bay's climate accelerates the timeline in two specific ways:

Thermal Cycling

Every time a window transitions from the cool of air conditioning to the heat of direct sun exposure, the glass, spacer, and sealant expand and contract slightly. On a south or west-facing Tampa Bay window, this cycle can happen multiple times daily: morning sun on a west-facing window is absent, then the afternoon sun drives the surface temperature significantly higher, then evening cools it back down. Over years of this daily cycling, the repeated expansion and contraction fatigue the sealant at the perimeter of the IGU. Tampa Bay windows experience more total thermal cycles than windows in northern climates that have a real winter and more moderate summers.

Humidity Pressure

Tampa Bay's ambient humidity -- regularly above 70% during the wet season -- means that when a small breach in the IGU seal occurs, moist air at high relative humidity enters the cavity quickly. A unit with a microscopic seal failure in a dry climate might take years to show visible fogging; the same unit in Tampa Bay's humidity shows visible condensation between the panes within months of the seal breach.

What Fog Between Panes Actually Tells You

The fog, haze, or mineral staining you see between the panes of a failed IGU tells you the insulated cavity has been breached and the thermal performance of the unit is degraded. The argon gas fill (in units that originally had it) has long since escaped and been replaced by humid ambient air. The unit is no longer providing the thermal barrier it was designed to deliver.

What it does NOT necessarily mean:

It does not mean the window frame is failing. The frame may be in excellent condition with a failed glass unit inside it.
It does not mean all the windows are failing. IGU failure is often localized to the most thermally stressed units -- south and west exposures, skylights, windows over radiators or HVAC vents -- while windows on north or east exposures in the same home remain intact.
It does not mean the window is structurally unsafe or will fail imminently. A fogged IGU is a performance and aesthetic defect, not a safety hazard.

Options for Addressing Failed IGUs

IGU Replacement (Glass Unit Only)

For windows where the frame is solid, the operation is smooth, and the only failure is the glass unit, replacing just the IGU is typically the most economical option. A window glazer or glass shop fabricates a new sealed unit to the exact dimensions of the existing unit and installs it in the same frame. This is not a handyman job -- it requires access to IGU manufacturing or supply channels, specialized tools for removing and installing the sealed unit without damaging the frame stops, and the ability to order units in the right thickness and spacer specification. The cost of IGU-only replacement is significantly less than full window replacement, and the result is a new insulated unit in a frame that still has remaining service life.

Full Window Replacement

When the frame itself is damaged, warped, difficult to operate, or when the window style is being changed, full window replacement makes sense. A window contractor removes the entire window unit including the frame and installs a new window in the rough opening. This is more expensive and more disruptive than IGU replacement, but it addresses the full system including frame seal, operation, and glass all at once. For older aluminum single-pane windows in homes built before the 1990s, full replacement to double-pane or impact-rated windows is often a significant energy and comfort improvement that justifies the cost.

Defogging Services

Some companies offer window defogging as a service: they drill a small hole in the spacer, inject a cleaning agent to remove the mineral deposits, insert a desiccant device to absorb future humidity infiltration, and seal the hole. This does not restore the original argon gas fill or the seal performance of the IGU -- the unit remains technically failed and will continue to allow some moisture infiltration. Defogging improves clarity temporarily in many cases but is not a permanent fix. For homeowners who want to defer the cost of replacement, defogging buys time. For homeowners preparing to list a home where an inspector will note the failed seals, defogging does not address the underlying deficiency that shows up in a home inspection report.

The Caulk-and-Frame Seal Distinction

Window seal failure (IGU failure) is different from exterior caulk failure around the window frame -- and both are common in Tampa Bay homes. Exterior caulk seals the gap between the window frame and the wall surface, preventing water infiltration around the window perimeter. Caulk failure shows as cracked, shrunken, or missing caulk bead at the window frame edges. This is a handyman repair: remove the failed caulk, clean and dry the joint, and apply new exterior-grade caulk appropriate for the surface material (polyurethane for wood trim, silicone or hybrid for stucco and vinyl). Many Tampa Bay homeowners confuse the two: they see foggy windows and failed exterior caulk together on an older window and assume they are related. They are two separate issues with separate fixes. Exterior caulk replacement is something we do regularly; IGU replacement is a glass shop or window contractor job.

What Best Bay Services Handles

We handle exterior window caulk replacement -- one of the most common maintenance items on Tampa Bay homes built in the 1980s through 2000s where Florida's heat cycling has dried and cracked the original caulk. We also handle window hardware: latches, operators, and pulls that have failed or become difficult to operate. What we do not do is replace IGUs or full window units -- that work goes to a glass shop or licensed window contractor. For homeowners who are not sure which type of window problem they have, a first call to us helps sort out whether it is a caulk, hardware, or glass unit issue. Call (813) 416-8676 to schedule a window assessment.