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Diagnose the symptom first
A draught you can feel. Hold a lit match or a strip of tissue near the perimeter on a windy day. If the air is moving at the sash meeting rail or along the weatherstripping, that is often a repair: new weatherstripping, an adjusted or replaced lock, a tightened hinge. If it is moving at the trim or behind the casing, the air is bypassing the window entirely, and that is a sealing and insulation job, not a window job.
Fogging or haze between the panes. The sealed unit has failed and the gas fill is gone. The frame, hardware and installation may be perfectly sound. On many modern windows the insulated glass unit can be replaced on its own, leaving the frame in place. Ask about that before you accept a whole-window quote.
A sash that will not stay up. On an old double-hung, this is usually broken sash cords, a failed counterweight or a worn balance. It is a repair, and often an inexpensive one.
Condensation on the inside of the glass. Usually a sign that indoor humidity is high and the glass surface is cold. New glazing will raise the surface temperature, but check the humidity source first: bathroom and kitchen ventilation, a humidifier setting, an unvented crawl space.
Soft wood at the sill or lower rail. Probe it with a screwdriver. Localised rot can be cut out and repaired. Widespread soft wood, especially at the joints, points to replacement, and to finding out where the water is getting in.
A window painted shut, stiff, or hard to lock. Annoying, not structural. Usually repairable.
Cracked glass in a single pane. Replace the glass, not the window.
Repair usually wins when
- The frame and sill are sound and the problem is hardware, weatherstripping or a single failed sealed unit.
- The windows are original to an older Wisconsin home and the joinery is good. Old-growth wood sash, properly maintained with storm windows, can outlast a cheap replacement unit.
- The house is in a historic district where appearance is regulated and a matching replacement would be expensive or restricted.
- You are selling soon and the windows are functional.
- Only one or two windows are a problem.
Replacement usually wins when
- Frames or sills are rotted or structurally compromised at several windows.
- Sealed units have failed across the house and replacement glass is no longer available for the product line.
- The windows are single-glazed with no storm windows and the rooms are genuinely uncomfortable to use in January.
- Hardware is obsolete and parts cannot be sourced.
- You are already opening up the exterior for siding or structural work, so the access cost is shared.
- The windows do not open, in a bedroom. Raise this with your building department; see window permits.
The rebate angle
If a rebate is part of your thinking, note what the Focus on Energy programme requires: you must be replacing existing single-pane or clear double-pane windows with ENERGY STAR Version 7 Northern Climate Certified models, through a participating Trade Ally contractor, with a reservation approved before purchase [W2]. Repairs are not covered, and the current purchase-and-installation window runs from June 1, 2026 to December 15, 2026, while funds last [W2].
That is a reason to understand the dates, not a reason to replace something that could be repaired. Anyone starting now should ask a contractor whether a before-purchase reservation and an installation finished by December 15, 2026 is still achievable, and should know that 2027 terms were not published as of November 13, 2026. Confirm current terms with Focus on Energy on 800.762.7077. See the rebate page.
The cost comparison, honestly
We can give you the replacement side of the comparison from a source: a 2026 This Old House survey of 1,000 homeowners put the national average at $517 per installed window, with an average total project of $7,183 [W1]. That is a national survey average, not a Wisconsin price and not a quote.
We have no sourced figure for what a window repair costs, so we are not going to print one. Get a repair quote and a replacement quote for the same windows, and compare those. Glass companies, carpenters and sash restoration specialists quote repairs; most replacement contractors do not.
Don't skip the cheap things first
Before either job, there are measures that cost far less per degree of comfort: storm windows, interior storm panels, weatherstripping, sealing the rim joist, attic hatch insulation, and a whole-home energy assessment to find out where the heat is actually going. In many Wisconsin houses the windows are not the biggest leak, they are just the one you can feel.
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