If you live in an older Bay Area home, you’ve probably felt it: a cool ribbon of air sliding off a window on a foggy morning, or a curtain that stirs when nobody opened anything. Drafty windows are one of the most common complaints in our older housing stock, and a lot of the time the fix is cheap and well within reach for a homeowner. The trick is knowing which leaks you can handle yourself and which ones are telling you something bigger is wrong.
This guide walks through the usual causes, the safe DIY fixes, and the clear signs it’s time to bring in a licensed pro.
Why older Bay Area windows leak
Much of the Bay Area’s housing was built decades ago, and a good share of it still has original single-pane wood windows. Wood moves. Through years of damp winters and dry summers, frames swell and shrink, joints open up, and the old weatherstripping inside the window gets brittle or just wears away. Caulk that sealed the trim when the house was painted years ago dries out, cracks, and pulls loose.
Our climate actually works in your favor here. We don’t get the deep freezes that punish windows in colder regions, so most of what you’re fighting is comfort, dust, a little noise, and small energy loss rather than frozen pipes or ice. That means the stakes on a DIY attempt are low, as long as you stay away from anything structural.
Find the draft before you fix anything
Don’t buy a single thing until you know where the air is actually coming in. Pick a breezy or windy day and try one of these:
- Wet the back of your hand and move it slowly around the edges of the closed window. Moving air feels cold on damp skin, and you’ll feel the leak before you see it.
- Hold a lit candle or an incense stick near the seams. If the flame or smoke pulls sideways, you’ve found a draft. (Keep it away from curtains and don’t do this near gas.)
- On a sunny day, look for daylight at the corners and along the sash.
Check the whole perimeter: the joint where the trim meets the wall, the joint where the frame meets the trim, and the moving parts of the sash. Note which gaps are fixed (they never move) and which are on parts that open and close. That difference decides your fix.
Caulk the fixed gaps
Caulk is for joints that don’t move. The classic spot is where the window trim meets the wall, or where the frame meets the trim. If you feel air there or see cracked, shrunken old caulk, that’s your target.
Scrape out the old, loose caulk first and wipe the surface clean and dry. Run a steady bead of a good exterior-grade or paintable caulk along the joint, then smooth it with a wet fingertip. Let it cure as the label says. That’s it. It’s one of the highest-payoff hours in home maintenance.
One warning: never caulk a part of the window that’s meant to move. If you seal the sash shut, you’ve traded a draft for a window that won’t open.
Weatherstrip the moving parts
The sash (the part that slides up and down or swings open) needs weatherstripping, not caulk. Old foam or felt strips flatten out and stop sealing. Peel the worn stuff off, clean the channel, and apply fresh weatherstripping sized for the gap.
There are a few types: adhesive-backed foam tape for flat surfaces, V-channel for the sides of double-hung sashes, and felt for lighter duty. For the bottom of a door-height window or a sliding unit, a sweep can help. Take the old piece to the hardware store so you match the profile and thickness. Too thick and the window won’t close; too thin and it won’t seal.
This is genuinely a beginner job. Most of the work is cleaning the old adhesive off and measuring carefully.
Don’t forget the easy add-ons
If a room still feels drafty after sealing, lined or heavier curtains and cellular shades cut the chill noticeably on foggy nights. Removable interior storm panels and clear window film kits are low-commitment options for a single problem window, and they peel off in spring. None of these touch the structure, so they’re safe to try.
When to call a licensed pro
Some things are past a tube of caulk, and trying to push through them can cost you more or put you at risk. Call a licensed window or remodeling professional when you see:
- Foggy or cloudy glass between double panes. That’s a failed seal, and the glass unit or window needs replacing.
- Soft, spongy, dark, or crumbling wood anywhere on the frame or sill. That’s rot, and it can spread into the wall framing. This is structural and not a patch job.
- A window that won’t open, won’t close, or won’t latch. Forcing it can break the sash.
- Any sign of lead paint. Homes built before 1978 often have it, and disturbing it has real safety rules. Don’t sand or scrape suspect paint yourself.
- Anything that means opening up the wall, the trim, or the framing.
For window replacement, rot repair, or structural work, hire a licensed local contractor and confirm the license before work starts.
A quick note on scope: our brand is an information resource and doesn’t perform window, plumbing, or electrical work. For appliance and HVAC service in the Bay Area, our sister company ADRIUM Service Solutions is a California-licensed contractor that handles that work. For windows and remodeling, go with a licensed pro in your area.
The bottom line
Start by finding the draft, match the fix to the gap (caulk for fixed joints, weatherstripping for moving sashes), and you’ll solve most older-window leaks in an afternoon for very little money. When you hit fogged glass, soft wood, or a window that won’t work right, stop and call a licensed pro. Those are the signs that the window is asking for more than a seal.