Why fall is the time to re-caulk

Caulking is the flexible bead that seals the joints around windows, doors and trim on the outside of a house. It doesn't last forever. Sun, rain and the swing between summer heat and winter cold slowly make it hard and brittle, and it starts to crack or let go of one side of the joint.

Fall is the best time to fix that, before winter arrives.

Why fall, and not winter

Most exterior sealants need the surface to be clean, dry and above about 4 °C when they go on. Every product is a little different, so the label on the tube has the final word.

In much of Ontario, fall still gives you dry, mild afternoons. Once the cold settles in, those days get rare, and frost and snow make it hard to get a joint truly dry.

What a gap does over winter

Water that gets into a gap can freeze, and ice takes up more room than water. Freezing and thawing again and again can push a small crack wider and let water reach the wood and the wall behind the trim. Gaps also let cold air in around the frame.

What to look for

Walk around the outside of the house on a dry day and look closely at:

• Window and door frames, especially the bottom corners
• Joints where trim meets siding or brick
• Corners of the siding
• Places where pipes, vents, wires or hose taps pass through the wall

Signs it's time: cracks, gaps, a bead that has pulled away from one side, pieces missing, or caulk that has gone hard instead of slightly soft.

Doing it right

• Remove the old caulk rather than covering it. A new bead doesn't stick well to old, failing caulk.
• Clean and dry the joint so the new sealant can grip.
• Fill deep gaps with foam backer rod first, so the bead is the right shape and only sticks to the two sides of the joint.
• Use a sealant made for outdoor use and suited to the surfaces you're joining.
• Tool the bead smooth so it's pressed into the joint.
• Leave weep holes and drainage gaps open. Some windows and siding have small openings meant to let water out. Don't seal those.

Morning dew and frost can leave surfaces damp well into the day, so midday to mid-afternoon is usually the best time to work.

Missed the window?

Some sealants are rated for colder weather and can go on during dry, frost-free days in winter. Check the label for the lowest temperature it allows.

We re-caulk windows and doors across Simcoe County, York Region and the Grey Highlands area. If you'd like us to take a look, book a walkthrough below.