Caulk plays an essential and often overlooked role in keeping your home airtight, watertight, and looking its best. It’s an effective and inexpensive weapon in deterring costly repairs and unwelcome pests. And best of all, most homeowners can tackle caulking jobs without hiring a pro. You only need to know some basics and spend a little time practicing your caulking skills. 

Where to use caulk?

Houses have hundreds of seams—locations where various building materials are adjoined, but small gaps occur. Some of those gaps, especially in bathrooms, kitchens, and along exterior walls, are routinely exposed to water. If left unsealed, water damage is highly possible. 

Other gaps allow exterior air to flow into your home, reducing energy efficiency and driving up heating and cooling bills. Cracks along exterior walls can also make it easier for insects and mice to enter your home. 

Caulk provides a convenient way to close those gaps. Some of the most common applications include sealing and waterproofing these areas:

• The perimeter of exterior window and door frames
• Shower and bathtub seams
• Wherever countertops meet walls
• Sink perimeters 
• Where toilet bases meet the floor 
• Anywhere that old caulk has cracked or rotted

Select your caulk.

Many types of caulks can be used in various applications and on different types of surfaces. When shopping, it’s best to read the product labels carefully and keep these points in mind: 

Packaging - Caulk comes in squeezable tubes and cartridges. The tubes contain less material suitable for quick, small jobs, while cartridges must be loaded into caulk guns, usually providing greater control. 

Color - Tinted caulks can make selecting a shade that coordinates with your tile or countertop easier. Others are clear. If you’re using caulk in a location where you’ll want to paint over it, like around an exterior window with wood trim, select a paintable caulk.

Temperature - Make sure the caulk can handle whatever temperature range it will be exposed to, especially for exterior applications. You may also need to apply it before the weather turns cold.

Common types - Two materials dominate most retailers’ caulk offerings—acrylic latex and silicone. Acrylic latex is an all-purpose product that is usually paintable and easy to clean up. 

Silicone's main advantage is its flexibility, which provides superior water resistance. However, you usually can not paint over silicone caulk. Sometimes, silicone is added to acrylic latex caulk, but you can also buy pure silicone.

Gather essential equipment.

In addition to whatever type of caulk you select, these tools can make most jobs go faster and easier:

• A caulking gun
• Utility knife 
• Metal scraping tool
• Caulk finishing tool
• Painter’s tape
• Long, thin nail or a metal coat hanger (to puncture the caulk tube)
• Rags
• Rubbing alcohol 
• Household cleaners and degreasers
• Vacuum cleaner

Caulk application tips.

The hardest part is applying the caulk evenly and maintaining a straight line. Practice helps! (Use some scrap pieces.) For the best results, follow these steps:

1. Remove any old caulk.

Use a sharp utility knife or a scraper to detach any existing caulk. If the old caulk is silicone, you’ll probably be able to grab one end and pull off an entire strip. Other types of caulk will require more scraping, especially if the caulk is old, dry, and hardened.

2. Clean the surface.

Vacuum up any remaining residue. Clean the surfaces thoroughly with an appropriate product if they have any dirty or tacky spots. Otherwise, wipe everything down with a rag dampened with rubbing alcohol. Rinse with water and let dry.

3. Tape caulk lines.

Professional installers may be able to skip this step, but it’s the best way for DIY homeowners to ensure a caulk job with clean, straight edges. Use painter’s tape to outline your caulk boundaries.

4. Apply the caulk.

Cut the tip off the caulk tube using a 45-degree angle. Don’t remove too much! Ideally, the width of your cut should equal the gap you intend to fill. Puncture the seal and load the tube into your caulking gun, positioning the opening “down.” Carefully pull the trigger and apply a bead by holding the tube at a 45-degree angle and pulling it towards you steadily. 

5. Smooth the seam.

Use a caulk finishing tool to smooth out the bead and ensure the edges adhere to each side. You can also use a wet finger or a rag dipped in water (if using latex caulk) or rubbing alcohol (for silicone caulk). 

6. Final clean up.  

Pulling at an angle away from the seam, gently remove the painter’s tape before the caulk sets. Quickly wipe up any excess caulk that may have dripped from the tape.

Now, you only need to give your caulk adequate drying time before allowing it to get wet. Depending on the type of caulk used, this may take hours or days. Depending on the type of caulk used, this may take hours or days.