Caulk 101: Why, Where, and How to Use it

Emma from ECOS 05/30/2024

What is caulk, how do you know when and where you need to use it, and what benefits are there to including it in your next home project? In this Caulk 101 Guide, we will explain everything you need to know about caulking and how to get the best results from it for your next home painting job.

What Is Caulk?

Caulk is a moldable material that's used to fill in and seal gaps between different building components such as windows, doors, interior moldings, and cabinetry. It usually comes in a squeeze tube or a cartridge that will need to be used with a caulk gun.

What Are the Different Types of Caulk

There are many different kinds of caulk, including silicone, acrylic, or butyl rubber, each with its own purpose.  Let’s break down when to use different types of caulks for your home projects (and which are best for painting). You’ll also want to check the information on the outside of the tube to make sure a certain type of caulk is paintable.

Acrylic Caulk

Acrylic caulk is sometimes referred to as “painter’s caulk” because it’s the most paintable caulk option and easy to use for both professionals and DIYers. You can use acrylic caulk on a variety of paintable home surfaces including drywall, wood, brick, and stone.

A benefit to latex caulk is that it’s water-based, meaning it’s easy to clean up with just a rag and some water. They are also often low in odor, pairing well with water-based, zero-VOC* paint for health and environmentally-aware DIY projects.

Silicone Caulk

Silicone-based caulk is good for weatherproofing around doors and windows, but you can't paint over it. You will want to use silicone caulk for non-painting projects that need to stand up to extreme temperatures or be waterproof. It also can be more difficult to apply than other caulks, but is the right option for certain home projects where non-paintable substrates meet, for example, at the joint between a bathtub and the surrounding tile.

Butyl Rubber Caulk

Butyl rubber caulk is a specialty caulk that is only for outdoor use. While you can paint over butyl rubber caulk, it needs to dry for at least two days before it's ready for paint. It's the caulk that you would want to use for outdoor home projects such as sealing gutters, vents on the roof, or drain spouts since it can withstand extreme temperatures and has a strong, water-tight seal.

Why Should You Use Caulk?

The best answer for why to use caulk is that houses shift, breathe, and move throughout the years. For example, you may notice that the molding around a doorway sticks out from the wall by an eighth of an inch. This small gap would be caulked if you were painting the trim so that it appears that it's attached to the wall perfectly. Using an acrylic caulk also means that you can paint over it once the gap is sealed.

Another important benefit of using caulk is to seal up sources of drafts. Small gaps around windows and doors can really let the cold in, especially in the wintertime and colder climates. Not only does this help keep your home at the right temperature, but it can also help reduct your energy bills from the heat or A/C escaping out the gaps.

When Should You Use Caulk?

Caulking should be done before painting so that you can hide the caulked area and reduce any imperfections or mismatched colors. If you need to repair the area that you will be caulking and painting, you’ll want to do that first and have it cleaned up before you start caulking to reduce imperfections or messes. Once that’s done and the caulk is dried, you’re ready to paint with the paint color of your choice!

Where Should You Use Caulk?

You’ll want to use caulk in an area of your house that has gaps causing a gap between different building materials. Think about it like keeping stuff (like drafts) out or fixing the aesthetic issues that can occur when materials don’t quite match up.

One of the most common places to use caulk is the trim around a window. If the boards aren't meeting at a perfect joint, then caulk can be used to mask that small error in carpentry. Using an acrylic caulk also means that you can paint over it when you’re done, matching the boards. 

Any baseboards, trim, or moldings that are going to be painted will also look better if you use caulk at their joints or where they meet the walls. The caulk will give a smoother, more uniform finish to all painted trim, and will give your paint job a much more professional appearance.

How Do You Use Caulk?

Ready to get started on your first DIY caulk project? Follow this step-by-step guide to using caulk for your next project.

  • Step #1: Most tubes of caulk will have a sealed, pointed tip at the end. Use a utility knife to cut the tip diagonally at the very end. You want the hole to be small to make sure that you are distributing the right amount of caulk while you’re working, so don’t cut too far down where the opening gets wider.
  • Step #2: Now you need to poke a hole in the tube of caulk, or it won’t come out. There's a small piece of wire on the caulk gun that swivels out from below the shaft. Take this piece of wire and insert it through the tip of the caulk until you feel it puncture the tube. Do this a few times. Wipe off the wire when you pull it out, or you'll get caulk all over your hand while you are using the gun.

  • Step #3: Put the tube of caulk into the shaft of the gun and pull the trigger until you feel it meets some resistance. Place the tip of the tube on the crack you want to fill and gently pull the trigger of the gun as you pull the tube across the crack. You want a small, thin, uniform line of caulk over the surface of the crack. You should be continuously moving the caulk gun, not staying in a single spot so you don’t get a large build-up of caulk in one area.

  • Step #4: Next, use your finger to lightly smooth the caulk into the crack. Go in one direction, pulling your finger across the surface of the baseboard. Wipe the excess caulk off your finger with a wet rag. This may seem messy at first, but it won’t take long until you know how much pressure to put on the trigger of the caulk gun to get the right amount of caulk out, which will decrease the excess coming off onto your fingers.

  • Step #5: Wash your hands with soap and water when you're finished. Depending on how much caulk was used and how big the gaps are that you are sealing, the caulk should be dry after a couple of hours. If you need to, you can apply more caulk to any areas that were not completely filled during the initial application. After that, you’re ready to get started on adding your chosen paint color!

Here's a short video that also shows you how to caulk.

Learn Other DIY Painting Skills with ECOS Paints

Caulking is a relatively easy painting skill that should make a vast improvement in the quality of your paint job. We highly recommend you don’t skip this step the next time you're painting a room to make sure you’re sealing every gap for a picture-perfect finish. 

Once you’re ready to get started, check out our water-based trim paints for the perfect topcoat to use after your next caulking project! You can also check out our other painting tips so that you can become a well-rounded, DIY painting pro.

CATEGORIES Tips & Tricks


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