THE SHORT ANSWER
Before adding a seal, note where the air seems to move: at the opening sash, where the frame meets the wall, or generally near the glass. Make sure the window closes and locks normally, then look for visible gaps or damaged weatherstripping from indoors. A cold feeling alone does not locate a leak or prove that the window needs replacement.
Before you try anything
Stay on the floor and work from indoors. Do not lean out, climb a ladder, remove a sash or dismantle a lock. Keep children away from an open window. Do not use candles, incense, a heat gun or a fan-and-exhaust test to find a draft. Preserve emergency escape openings, drainage paths and intended ventilation. Stop if glass is cracked, the sash is loose, the window will not stay supported or wet electrical equipment is nearby.
Before you begin
For an accessible residential window with a dry, intact interior area and no immediate security or fall hazard. These observations help you explain a comfort problem to the manufacturer, landlord or an energy assessor. They do not diagnose hidden installation defects, water entry, glass failure or whole-house ventilation. Window designs and climate conditions vary.
A note of the room, weather and wind conditions; a photo of the suspected area; and the window brand or product label if already accessible. A flashlight may help with a visual check. You do not need sealant, foam, tools or a smoke source.
In a rental, report the problem to your landlord or property manager before making repairs. Building rules and local requirements vary.
Work through the checks
- 01
Record the location and conditions
From a safe indoor position, note whether the sensation is concentrated at the moving sash, along the interior trim or across the glass. Write down when it occurs. A windy-day observation can be useful to an assessor, but it is not a measurement of air leakage.
- 02
Check normal closure without forcing
If the window operates safely, close and lock it using the normal controls. Closed and locked windows can seal more tightly. If it resists or will not latch, stop and report that behavior instead of pushing harder or adjusting hardware yourself.
- 03
Inspect the visible weatherstripping
Look for a loose, torn or missing section along an accessible edge. Weatherstripping is the compressible seal between the sash and frame. Photograph what is visible; do not pull out a seal or assume that a generic strip fits the window.
- 04
Separate the sash edge from the wall edge
Note visible gaps where interior trim meets the frame or wall as a separate observation. The locations help a professional choose what to inspect. Do not remove trim, fill a hole or treat a visible interior gap as proof of the outside entry point.
- 05
Identify the product before choosing parts
Find the model through an existing record or safely accessible label. Ask manufacturer support which weatherstrip and procedure match it. Andersen specifically calls for product identification before selecting replacement seals. Renters should report the observations to maintenance.
- 06
Use an assessment for a persistent or unclear draft
If closure is normal and no obvious seal problem is visible, ask for a window or home-energy assessment. DOE describes professional blower-door and infrared methods for locating air leakage. Leave those tests to a qualified assessor who can also consider ventilation and combustion safety.
What your result means
These observations help choose a next step. They do not confirm a diagnosis.
| What you notice | What it tells you | Next step |
|---|---|---|
| Draft seems concentrated at a sash edge | Closure or a weatherstrip issue may be involved | Report the exact edge, closing behavior and visible seal condition. |
| A gap is visible at interior trim | The frame-to-wall area needs assessment | Photograph it without removing trim or filling unknown openings. |
| Cold sensation near glass without a clear moving-air point | The source of discomfort is not established | Record conditions and request an assessment before choosing a repair. |
| The window resists closing or locking | Normal fit or operation needs attention | Stop forcing it and contact the manufacturer or maintenance. |
| Water, broken glass or an unsupported sash is present | This exceeds a routine draft observation | Keep clear and arrange help for the immediate hazard. |
Know what happens next
Check the outcome
After an approved repair, confirm normal opening, closing and locking. Compare comfort in similar weather and note any remaining air movement. Check that drainage, ventilation and emergency escape functions remain available. A brief improvement is useful feedback, but it is not a measured energy saving or proof that all leakage has stopped.
When to call a professional
Use qualified window service for damaged hardware, unsafe operation, moisture damage or uncertain installation. For several drafty rooms or an unclear source, request a whole-home energy assessment. Air sealing must account for fresh-air needs and fuel-burning equipment; do not block vents or undertake a pressure test yourself.
Take useful notes with you
A short record makes it easier to explain the problem to a landlord, technician, or responder. Do not collect notes during an emergency.
Notes stay in this page until you leave or reload. Download a copy to keep them. They are not sent to us.
Common questions
Should I caulk every opening around the window?
No. The moving sash, fixed frame, drainage paths and intended vents serve different purposes. Have the actual leak and approved sealing location identified first.
Does a draft mean I need a replacement window?
A draft alone does not establish that. The condition of the product, fit and installation must be assessed before deciding whether care, repair or replacement is appropriate.
Will any adhesive weatherstrip work?
Do not assume so. Match the replacement to the product and its instructions; a strip that interferes with closing can create another problem.
Can I tape a bedroom escape window shut for winter?
Keep emergency escape operation available. Ask the manufacturer or a qualified professional for an option compatible with the window and local requirements.
Sources & scope
This is a desk-researched guide, not a hands-on test or an on-site diagnosis. A licensed tradesperson has not independently reviewed this edition. Follow your product’s manual and local requirements.
- Andersen Windows — Why Winterize Windows?
Accessed 2026-10-10. Supports checking trim gaps, damaged weatherstripping and normal closing/locking; identifying the product before selecting replacement seals; and seeking service for fit problems. Product-specific advice is not a universal repair method.
- Andersen Windows — Window and Door Glossary
Accessed 2026-10-10. Defines sash/frame weatherstripping, locks and drainage weep holes. These distinctions support recording locations and preserving function; they do not identify a particular window defect.
- U.S. Department of Energy — Consumer Guide to Air Sealing the Home
Accessed 2026-10-10. Supports professional assessment, blower-door/infrared leak location and the need to consider ventilation and combustion safety with air sealing. It does not support a reader-performed depressurization test.
Published 2026-10-11 · Our editorial policy · Report a correction