How often should you check exterior window and door trim?

Short answer

Inspect the exterior window and door trim once a year. The trim is the wood or composite framing around every window and door, and the caulk between it and the siding is what keeps rain out of the wall. A walk around the house with a putty knife, pressing on the wood and checking the caulk, takes 30 to 60 minutes. Fixing what you find costs $10 to $30 in caulk, filler and paint, and a handyman charges $150 to $400 to recaulk and touch up a whole house.

Why it matters

Every window and door is a hole in the wall, and the trim around it is the patch. Rain hits the trim directly and runs down it, and the only things stopping water from getting behind it are the caulk at its edges and the paint on its face. Caulk shrinks and cracks over a few seasons. Paint chalks and peels. Once either fails, water runs behind the trim into the sheathing and the framing, and the trim itself, if it's wood, soaks it up.

Wood that stays wet rots, and rotten trim doesn't stop water at all. The bottom corners of window trim and the base of door frames go first, where water collects. By the time the rot shows on the outside, it's usually spread into the sill or the framing behind, and a repair that was a tube of caulk becomes carpentry. A yearly check catches the crack in the caulk while it's still a crack.

When to do it more often

The index gives no modifiers, so once a year holds. Where it lands in the year matters: spring, so you can see what winter did and fix it before the summer rains, or fall, before the freezing starts. The side of the house that takes the weather, which is usually the one facing the prevailing wind, deserves a second look after a stormy season, and so does any trim that's shaded and slow to dry.

What you need

A caulk gun
A putty knife, to probe the wood and scrape loose paint
A paintbrush
A ladder, for the upper windows
Exterior caulk, a paintable one made for outdoor use
Exterior primer and paint matched to the trim
Wood filler, for small soft spots and nail holes

Steps at a glance

Walk the house and look at the caulk line around every window and door for cracks, gaps and places where it's pulled away.
Press the putty knife into the trim at the bottom corners and along the sills. Sound wood resists. Soft wood is rot.
Scrape away cracked caulk and loose paint, and fill small soft spots with wood filler once they're dry.
Run a new bead of exterior caulk along every gap between trim and siding, and at the joints in the trim itself.
Prime bare wood and filled spots, then paint them to match.
Note any trim that's soft deeper than the putty knife tip, which needs replacing rather than filling.

You're done when every caulk line is continuous, no bare wood shows, and the putty knife finds nothing soft.

Signs it's overdue

Cracked or missing caulk around a window or door.
Peeling paint on the trim, especially at the bottom.
Wood that's soft when pressed, or that the putty knife sinks into.
Gaps you can see daylight through from inside, around a door or window frame.

DIY or pro

This is an easy job at ground level and a moderate one on a ladder. Caulking takes a steady hand and a wet finger to smooth the bead, and painting takes a dry day. The inspection itself is the valuable part, and anyone can do that.

A handyman charges $150 to $400 to recaulk and touch up the trim on a whole house, which makes sense for a tall house, a house with many windows, or a year when the caulk has failed everywhere at once. Trim that's rotten through needs a carpenter to replace it, and the sooner that happens the less of the wall comes with it.

Safety

Ladder and heights: the upper windows mean a ladder, and ladder falls are the common injury in exterior work. Set it on firm, level ground, don't lean out from it, and have someone hold it. Do the ground-level trim first and decide how much of the upper work you want to do yourself.

FAQ

How often should you caulk around windows?

Check the caulk once a year and replace it where it's cracked or pulled away. A good exterior caulk lasts several years, but the sunny side of the house fails first.

What kind of caulk do you use on exterior trim?

A paintable exterior caulk, such as a siliconized acrylic or a polyurethane. Pure silicone can't be painted over, so it shows.

How do you know if window trim is rotten?

Press a putty knife or a screwdriver into it at the bottom corners. Sound wood stops the blade. Rotten wood lets it sink in with little resistance.

Can you paint over old caulk?

If it's sound, yes, once it's clean. If it's cracked or pulling away, scrape it out and recaulk before painting, or the paint will crack with it.