Using and Applying Caulk

Caulk is relatively inexpensive and easy to apply. Caulk serves several purposes:

• It seals cracks which rob your home of conditioned air, making it more energy efficient.
• Different materials expand and contract at different rates and at different temperatures. Flexible caulk can seal the cracks that result from this movement.
• It provides a moisture barrier and seals water away from areas which could be damaged by rot or by the expansion of water as it freezes.
• It prevents insects from crawling through cracks into your home.
• It provides an attractive finish in corners and at the joints of unlike materials.

You may be surprised at the many types of caulks and sealers available. Each type is formulated for a particular purpose. You need to know what is best for different situations. Several different types are listed below with their purpose and typical characteristics. When shopping, always refer to the product packaging.

• Painter's caulk: Inexpensive latex caulk is often used by painters to plug holes and cracks prior to painting. It can also be used to provide a smooth joint in a corner where textured materials meet. This allows the painter to paint a very straight line in the corner when using contrasting paint colors.
• Acrylic latex: Paintable, acrylic fortified caulk for both interior and exterior applications. Cleans up with water.
• Siliconized latex: Very durable, latex caulk with silicone. Available in colors and cleans up with water.
• 100% silicone: Silicone caulk is great for non-porous substances. It is the best choice for sealing ceramic tile, glass and metal surfaces, but is less appropriate for porous surfaces like wood and masonry. Silicone caulk remains flexible and is impervious to water. It cannot be painted and must be cleaned up with solvent. It also has a sharp odor when curing. Requires adequate ventilation. Usually available in either clear or white.
• Tub and tile: Acrylic sealant gives a flexible, watertight seal. It is mildew resistant with water cleanup.
• 100% silicone kitchen and bath sealant: Has the same characteristics as plain 100% silicone sealant.
• Gutter and foundation sealant (Butyl Rubber): Can be used on metal, wood or concrete. Appropriate for use in areas which experience extreme temperature variations. Requires solvent clean-up. It is often used on metal flashing and around skylights.
• Roof repair caulk: Convenient butyl rubber/asphalt formulation for sealing flashing, roofing, skylights, etc. Cleans up with mineral spirits.
• Adhesive caulk: Used as an adhesive during the installation of sinks, countertops, etc. Dries harder than other caulks, but is less flexible.
• Concrete and mortar repair: Retains some elasticity to remain in cracks in mortar and concrete. Cleans up with water.

Some guns have a button which releases the plunger and relieves the pressure in the caulk tube, while others have a 90 degree bend at the end of the plunger rod which must be turned to release the pressure. Aside from the differences in release mechanisms, both guns operate on the same principal. Some caulk comes in a squeeze tube and does not require a gun at all.

Caulking can be messy, especially for the inexperienced. For example, if you do not release the trigger on the gun, caulk will weep from the tip. Also, if you use your finger to straighten a bead, you can end up with excess caulk on your finger. Of course, caulk is sticky stuff and wiping it off is not as easy as it may seem. After a while, a dirty film may show up on your fingers and smear on things you touch.

The easiest way to avoid creating problems is to learn to properly use the caulking gun. It is possible to create beads that do not require smoothing. If you can achieve that level of skill, you will not have to touch the bead with your hands. But, even if you never get quite that good, there are things you can do to make the job go better. Once you get the hang of it, a good gun and a properly cut tip will help make good beads a breeze.

Keep this advice in mind:

• You must remember to immediately release the gun trigger each time you complete a bead to reduce the amount of caulk which weeps from the tip.
• Always have rags or paper towels handy.
• Practice makes perfect. You can practice running beads in a corner using inexpensive painters' caulk. Just secure some paper or foil in a corner to create a practice surface, and apply the caulk to the corner as if your were doing it for real. Between beads, remove the paper or foil from the corner and throw it away. Then you will be ready to do it again and again until you are comfortable with the quality of your beads. It may seem wasteful, but it can save you time and problems in the long run. A single tube of caulk will likely be more than enough to help you gain confidence in your ability.
• If you use your finger to create beads you consider acceptable, apply the caulk sparingly. Always moisten your finger before touching the caulk. The moisture allows your skin to flow over the caulk and makes cleaning the caulk off much easier.
• Leave well enough alone. Trying to create the perfect bead is a good way to mess up an otherwise competent one.

There is a dispute among people who apply caulk about which method yields the best results. There are those who push forward with the angle of the gun, and those who pull against it. In fact, it is likely that some do both, depending on the circumstance. The most important thing is that you determine which method yields the best results for you. The whole point in either case is to allow the cut end of the applicator to shape the bead for you and force the caulk against the surfaces you intend to seal.

These drawings illustrate the two techniques for applying caulk. For best results, the applicator tip should be smoothly cut at a 45 degree angle. The exposed hole should be about 1/8" in diameter, or slightly smaller than the crack you wish to fill. By holding the gun at an angle similar to the cut tip with the edges of the tip straddling the joint to be caulked, the material will be forced into the joint at a fillet. If the angle and speed of application is kept consistent, as well as the pressure within the caulk tube, you should achieve very good results.

Note: Since the edges of the tip are riding along the surface of the materials being joined, the bead will conform to the texture of the materials. This makes it difficult to achieve completely smooth beads against rough surfaces; however, they do not need to be completely smooth to be aesthetically pleasing. It is important, though, that the edges of the bead be sealed against the edges of the surfaces you are sealing.

Tips and Notes ENERGY STAR home sealing guidelines state that careful homeowners can seal obvious cracks and gaps with spray foam or caulk and add insulation in the attic, basement, crawl space or open walls. However, insulation needs proper air-sealing to work well. A professional contractor can best help you identify the most important air leaks and safety measures to consider when weatherizing your home. Gaps, cracks and holes that are smaller than 1/2" can be filled with caulk. Holes that are 1/2" to 3" can easily be filled with spray foam. Holes bigger than 3" should be filled or covered with rigid foam insulation and then caulked around the edges. Cheap, low-quality caulks may dry out and lose flexibility in a few years. Better quality elastomeric caulks retain their tight seal under a wide range of conditions and can last 20 years or more. Elastomeric caulks are made of silicone, latex and/or acrylic material. Check the label to be sure the caulk is appropriate for your application.