How often should you reseal window frames?
Updated July 2026
Renew the exterior caulk where a window frame meets the siding about every 5 years, and give it a quick look yearly for cracks and gaps. Sun and seasonal movement dry out caulk until it splits and pulls away, and that open seam is where wind-driven rain gets into the wall and drafts get into the room. One important distinction: fogging between the panes is not a caulk problem at all, it means the sealed glass unit itself has failed and needs replacing.
What changes the interval
| Your situation | Interval | Why |
|---|---|---|
| Exterior perimeter caulk | Every 5 years | The seam between frame and siding is the main water and air path |
| Wood-sash glazing putty | Every 5–10 years | The bed that holds the glass dries, cracks, and drops out over time |
| Sun and weather-facing walls | Every 3–5 years | South and west elevations bake the caulk brittle fastest |
| Cracked or missing caulk found | Recaulk now | An open seam does not wait for the calendar to let water in |
| Fogging between the panes | Replace the glass unit | The insulated glass seal has failed; recaulking will not fix it |
| New-construction settling | Check at year 1–2 | Fresh framing shrinks and moves, opening early gaps in the caulk |
The cost of skipping it
What skipping it costs: a failed exterior seal is a slow, hidden leak. Water tracks into the wall cavity behind the trim, rotting the framing and sill and feeding mold, damage that can run into the thousands before a stain ever shows inside. A tube of quality exterior caulk is $8–15, and having a pro recaulk a house of windows is $150–400, a rounding error against wall repair or the $400–1,000 per window replacement that water damage eventually forces.
How to do it (10–20 minutes per window · DIY with a caulk gun)
- Inspect the exterior seam around each window for cracked, shrunken, or missing caulk and any daylight gaps.
- Cut away and pull out the old, failed caulk, then wipe the joint clean and let it dry fully.
- Run a bead of exterior-grade polyurethane or silicone caulk along the frame-to-siding seam.
- Tool the bead smooth with a wet finger so it sheds water and bonds to both surfaces.
- Leave the bottom weep gaps at the sill open; they are meant to drain, not to be sealed shut.
- Inside, check the sash weatherstripping and add a bead of interior caulk on trim if you still feel a draft.
Knowing the interval is the easy half. OnOtto reminds you at the right interval, and it won't let you snooze it into next year. Tasks persist until they're done, and completing window resealing schedules the next one automatically.
Put this on autopilot, free for 30 daysFrequently asked questions
What is the difference between resealing frames and replacing windows?
Resealing is exterior maintenance: renewing the caulk seam between the frame and the wall so water and air stay out, a cheap, recurring DIY job. Replacing the window means pulling the whole unit because the frame is rotted, the sashes will not operate, or the glass has failed. Many drafts blamed on old windows are really just failed caulk, so reseal first; if it stays drafty or foggy, then look at replacement.
Should I use silicone or polyurethane caulk?
Both work outdoors; the trade-off is paint. Polyurethane and high-quality siliconized-acrylic caulks are paintable and flex well, good where the bead shows and must match trim color. Pure silicone is the most durable and water-resistant but will not take paint, so use it where color does not matter. Whatever you choose, buy an exterior-rated caulk with a long warranty, not cheap painter's caulk, which fails in a season or two.
Can recaulking fix a foggy window?
No. Fog or condensation trapped between the two panes means the insulated glass unit has lost its seal and its inert gas has escaped, and no amount of exterior caulking reaches that sealed space. The fix is replacing the glass unit itself (often $150–400 per sash if the frame is good) or the whole window. Recaulking the frame is still worth doing for water and drafts, but it is a separate problem from the fog.