What’s Happening

Drafty windows are almost always a sign that the seal between the glass and frame has failed, or that the weatherstripping has worn past the point of doing its job. Either way, conditioned air is escaping and outside air is getting in, and your heating or cooling system is running longer to compensate.

Call (682) 281-2168

That extra run time is what shows up on your energy bill. The window itself isn’t broken in the dramatic sense – nothing has shattered, nothing looks obviously wrong from the street. But the thermal barrier that made the window worth installing in the first place is gone. Cold air pooling at the sill in winter, warm humid air pushing through the frame in summer, a faint whistle when the wind picks up – these are all the same problem at different stages. Left alone, a failed seal lets in more than air: moisture follows, and moisture inside a wall or inside a double-pane unit starts a much worse chain of events.

Why It Happens

Failed Insulated Glass Unit (IGU) Seal

Most modern windows are double- or triple-pane, with an inert gas like argon sealed between the panes to slow heat transfer. When the perimeter seal of that glass unit fails, the gas escapes and humid air takes its place. You’ll know this is the cause when you see a foggy or hazy film between the panes that doesn’t wipe off – it’s on the inside surface of the glass, trapped. The fog is worst in the morning and sometimes clears by afternoon, which is a reliable tell.

Weatherstripping Breakdown

Weatherstripping is the foam, rubber, or pile material that runs along the edges of the sash and presses against the frame when the window closes. It compresses thousands of times over its life and eventually stops compressing – it just sits there flat, creating gaps. Run your hand slowly along the perimeter of a closed window on a cold or windy day. If you feel air movement anywhere along that line, the weatherstripping is the likely culprit.

Frame Contraction and Expansion

Frames – especially older vinyl, aluminum, or wood frames – expand in heat and contract in cold. Over years of cycling, the frame can warp slightly or pull away from the rough opening in the wall. The gap might be microscopic, but at the corners it can open enough to let a steady stream of air through. Look for daylight at the corners of the frame when you’re inside with the lights off, or feel for air movement at the seam where the frame meets the wall trim.

Worn or Missing Glazing Compound

Older single-pane windows, and some wood-frame windows, use a putty-like compound called glazing to hold the glass in the frame and seal the joint. Glazing dries out, cracks, and eventually crumbles. You can see it: the edge where glass meets frame will have gaps, missing chunks, or a chalky texture instead of a smooth, solid bead. When the glazing goes, that joint is no longer sealed, and air moves freely through it.

What to Do Right Now

• Do a hand-test sweep. Close every window in the affected room, wait for a windy moment or turn on a box fan outside, and slowly run your palm around the frame perimeter. Note every spot where you feel air movement – photograph it if you can, because that documentation helps your technician triage the job before arrival.
• Check for fog between the panes. Stand a foot back from the glass and look at it at an angle. Fog, streaks, or a milky haze locked between the panes confirms a failed IGU seal. Write down which windows show it.
• Temporarily block the gap – carefully. A rolled towel at the sill or removable rope caulk from a hardware store can reduce heat loss while you wait for a professional. These are stopgap measures, not repairs, and they won’t show up on an energy bill as a meaningful improvement. They just keep the room livable.
• Don’t caulk the frame yourself yet. It seems like an obvious fix, but caulking over a gap without knowing what caused it can trap moisture inside the wall cavity. Let a technician assess the frame first.
• Photograph the exterior too. If you can safely see the outside of the window from the ground, a photo of the exterior frame condition – cracked caulk, rotting wood, gaps at the corner trim – gives your local Juniper Windows & Doors team a head start on diagnosing which windows need full replacement versus which might need weatherstripping alone.

How We Fix It

When your local Juniper Windows & Doors team arrives, the first thing a technician does is a frame-to-frame assessment: glass condition, seal integrity, frame plumb and level, weatherstripping, and the rough opening behind the trim. That takes about fifteen to twenty minutes per window and gives both of you a clear picture before anything is quoted.

If the damage is isolated to weatherstripping or the glazing compound, that’s addressed in the scope of a window service visit. If the IGU seal has failed or the frame has warped beyond correction, the path is Window Replacement – pulling the old unit and installing a new one, properly flashed and sealed into the rough opening. For a single window, a straightforward replacement typically takes two to four hours. Multiple windows in one visit follow the same process unit by unit.

Product lines like PGT, ECO Window Systems, and ViewLux offer thermally broken frames and high-performance glass units suited to a range of climates and budgets. Your technician will walk through the options that fit your opening size and your home’s style.

Every job comes with a written price before any work starts – that’s not a courtesy, it’s how Juniper operates on every project, every time. And every completed installation is covered by the 365-Day Done Right Promise: if it isn’t right, Juniper makes it right, in writing, for a full year.

Frequently Asked Questions

Get It Fixed

Call (682) 281-2168 – a real person answers, right now, any time of day or night. Your local Juniper Windows & Doors team will schedule your visit, give you a live arrival time to track, and put the price in writing before any work begins. No phone tag, no surprises.

Written by Sean Mackey, Owner & Installer at Juniper Windows & Doors, part of the Relay Home Co. family since 2001.