Can a Caulk Bead Be Too Thin?

Purpose of Caulk

• Caulk is used to seal joints and seams in wood and other materials to make those seams airtight and watertight. Caulking has long been used to seal wood seams in boats to keep them afloat. Today, caulk is commonly used to close gaps in the siding on homes or around windows or at the base of showers, tubs, sinks and toilets to prevent bugs, dirt and water from entering the home and to prevent water from seeping out of showers, tubs and toilets.

Types of Caulk

• Most caulks are made from silicone, polyurethane, polysulfide or acrylic. These materials form sealants that are movable. The chemicals that comprise these movable caulks are elastomeric in nature and allow the caulk to expand or contract from 25 to 50 percent within the space where the caulk is laid. Another nonmovable caulk is called construction caulk. This caulk is not elastomeric and is not designed to move but is solid. For this reason, it’s not advisable to fill windows, bricks or spaces around sinks and in everyday home use with this type of caulk. Some types of silicone and acrylic caulks can be painted and others cannot, so make sure you check the information on the caulk before buying it if you intend to paint over it.

Problems With Caulk

• If caulk is not applied properly, it may be laid on too thin. If not enough caulk is used to join two seams together, an inadequate amount of caulk will come to rest in the space between the two joints. When this occurs, the caulk expands and contracts in the space where it is applied, but never fully, resulting in an inadequately sealed joint that still allows dirt and water in or out of the space. Over time, caulk beads that are spread out too thin can crack and break causing damage to the space in which they were placed and the surrounding area.

How to Apply Caulk

• Use a caulk gun rather than your fingers to apply caulk to a window or other seam in your home. Insert caulk into the caulk gun and cut the tip off the caulk tube. Hold the caulk gun so that the tip of the caulk tube is at a 45-degree angle to the space you want to fill with caulk. Press the trigger and pull the gun toward you slowly. Press out enough caulk to form a convex bead that rises up rather than falls down into itself. Alternatively, you may hold the caulk gun at a 60-degree angle and push the caulk gun away from you as you fill the space with caulk. Either method will ensure an appropriate amount of caulk fills the space and protects the seam.