Signs your caulking needs to be redone

Cracks, peeling, hard joints

This sign is easy to see. The joint cracks down the middle, or it pulls away from one side of the frame or the brick.

A crack in the centre often means the product can no longer keep up with the building's movement. Peeling at the edge shows that adhesion has failed, often because the surface was dirty or damp when the joint was applied.

Either way, air and water get through. A cracked joint can't be fixed with a layer on top: it has to be removed and a new one applied.

A joint in good condition stays flexible. If you press it lightly with a fingernail, it should spring back.

Over the years, some products harden. The joint becomes brittle, crumbles or breaks into pieces when touched. It can no longer stretch or compress as materials move with heat and cold. The next crack is not far off.

Products that handle little movement are more prone to this. According to Natural Resources Canada, acrylic latex handles only 7 to 10% movement, while a silicone can reach 50% depending on the product.

Draughts and cold near the frames

Some signs are felt more than seen. A cold hand near a window frame, an electrical outlet that lets air through, a curtain that moves with the window closed.

To check, the Government of Quebec suggests the candle test: hold a flame or a stick of incense near frames and outlets. If the smoke bends, air is getting through. Be careful with the flame near fabrics.

A draught doesn't always come from the caulking. It can come from worn weatherstripping on the part that opens. We look at both during the assessment.

Weatherstripping wears out too. According to Natural Resources Canada, foam can crack over time, while ribbed rubber lasts longer. Weatherstripping that is flattened, torn or painted over no longer does its job: the Government of Quebec reminds us never to paint weatherstripping.

Water, stains and mould

Water on a window sill after rain, a stain on the wall below a frame, paint that blisters: these are signs to take seriously.

The Government of Quebec explains that warm, moist air escaping through leaks can cause hidden condensation in the walls. Over time, this moisture can damage the insulation and lead to mould and rot in the framing.

A blackened joint, especially indoors in the bathroom or kitchen, also deserves your attention. Before applying a new joint, the surface must be clean and fully dry. This Old House points out that a joint applied to a damp surface can let mould form underneath.

One inspection a year

This Old House recommends inspecting your joints once a year. Walk around the house and look at:

• the perimeter of windows and doors, inside and outside
• wall penetrations: dryer, range hood, faucets, wires
• the junctions between siding, brick and foundation
• window sills, for signs of water

What we do when a joint needs redoing

A new joint starts with removing all of the old one. We cut and scrape out the old sealant, then clean the surface. The Government of Quebec stresses this cleaning: paint, dust and old caulking must come off.

If the gap is wider than 6 mm, we install a backer rod, as NRCan recommends. We then apply sealant in the chosen colour and tool the joint so it is continuous and well bonded to both sides.

If we find rotten wood behind the joint, we tell you. Sealant doesn't hold on soft wood. The wood must be repaired, or protected with aluminum cladding.

Lifespan: theory and reality

How long does caulking last? There is no single answer.

The Natural Resources Canada chart gives more than 20 years for silicone, more than 25 years for polyurethane, and 5 to 25 years for acrylic latex depending on the brand. These are lifespans of the material alone. They don't account for installation, sun exposure or freeze-thaw cycles.

This Old House, for its part, talks about redoing joints every 3 to 5 years with consumer products. The gap between these numbers shows one thing: the product and the installation make all the difference.

For joints up high, such as second floors, gables or building façades, don't take chances on a ladder. Leave the inspection and the work to an equipped professional. We caulk year-round with DOWSIL™ sealants, and joints done with DOWSIL™ 791 carry a lifetime warranty on materials and labour, under the conditions written in the contract.