All About Caulk

When tiling kitchen backsplashes, tub, and shower surrounds or using glass tiles, caulk is needed to finish the job and flex when grout cannot. Understanding when the caulk is needed, and where it is best applied can help any homeowner achieve a longer lasting tile installation.

What is Tile Caulk?

Caulk has been used for centuries as a flexible joint filler. First used in ships, to join together wooden boards, today’s caulk fills a number of uses in the home. Caulk can be latex, or silicone based so that when dry, it flexes or bends with the natural movement of the house, absorbing movement that tile or grout cannot.

Tile caulk is available in the same colors and finishes as grout to form a cohesive tiling job and is typically used whenever a 90-degree angle is formed between tile, or between the tile and another hard surface such as a tub or counter.

Tile Caulk and Glass Tiles

Glass tiles are by nature more fragile and inflexible than other tile materials. Therefore, any natural settling of the house, movement of walls or floors or flexing of joints can cause the tiles to crack or pop loose from their mortar. Therefore, any time that glass tiles are used in an installation care must be taken to absorb any flex or movement that the glass is unable to accept. Part of this care is the use of sanded caulk.

When working with glass tiles, caulk must be inserted into every angle that the glass makes, as well as into transitions between the glass tiles and other materials. For example, when tiling kitchen backsplashes with glass tiles, caulk needs to be inserted between the kitchen counter and the tiles as well as in the corners of where two walls meet. While it is standard practice to use caulk in these areas at all times, porcelain, ceramic and natural stone tiles can be installed with grout in the corners without harm. Glass tiles require the use of caulk to help maintain their structural integrity.

Caulk and Showers and Tubs

The last thing any homeowner wants to see happen, is the grout or material joining their tile to their tub or shower floor comes loose, allowing water to seep behind the materials and damage the walls. When the natural filling of a tub with water increases the tub’s weight, there is a tendency for the tub to move slightly, or settle. If the material joining the tub to the tile can’t move with the tub, it may break or come loose, exposing the walls behind the tile to potential water damage.

Natural settling of a house over time can also cause floors to become out of level, causing a shower wall to separate slightly from a shower floor. Once again, the joint filler in these areas must form what is known as an expansion joint; it must flex with the walls and floor keeping the joint continuously filled and water tight.

Any time that two areas of tile join each other in a 90-degree angle, particularly at horizontal planes, caulk needs to be inserted in place of grout as a joint filler. Simply purchase caulk which matches the color and texture of the grout to ensure a cohesive look. For example, if white, sanded grout is used on the wall tile of a shower, white, sanded caulk should be used in the join between the shower walls and floor.

Tile caulk is an important part of nearly every wall tile, glass tile and shower tile application. Utilizing this material will help keep the tile job looking great for years to come, while protecting walls and floors from water damage. Use tile caulk the next time a tile installation is undertaken and know that the tile job is built to last.

How to Choose Caulk

The type of caulk you need depends on the project you are doing. Not all caulks are the same. Caulks are specialized for specific uses. Some caulks are paintable while others are not, some are flexible while others are stiff, and some are heat-resistant while others do not stand up to heat.

Reading labels and determining the correct caulk for the job is the first step in successfully using caulk. Caulking gaps, joints and seams are easy home improvement projects. Creating a caulk barrier protects homes from water leaks, heat loss and drafts. Using caulk correctly is important, but using the correct caulk is more important.

Acrylic Latex Caulk or a Silicone Caulk?

For the majority of household caulking jobs, you’ll use one of two types, either an acrylic latex caulk or a silicone caulk.

Acrylic latex caulk (or just “acrylic” caulk) is easier to work with and generally less messy than silicone caulk. Rule number one for a good-looking caulking job is if you don’t really need to use silicone caulk, don’t. It’s possible to apply silicone caulk and achieve a neat, finished appearance, but it’s a lot more challenging than with acrylic.

Acrylic caulk, also available in what is called siliconized acrylic caulk, is perfect for filling gaps before painting. It also works well around windows or other wall penetrations to stop air leaks inside or out.

Silicone caulk, on the other hand, is better where you absolutely want to prevent any possible water penetration.

You can use acrylic caulk to prevent water penetration, but acrylic caulk is prone to begin shrinking and cracking after a period of time. When the cracks begin to appear, you have to caulk again or risk having water entering where it shouldn’t.

Acrylic caulks may be rated as 25-year, 35-year or 50-year, but in reality, they won’t last nearly that long. Even the best acrylic caulk will begin to show signs of drying and cracking after a few years.

Silicone caulk, sometimes called siliconized rubber caulk, retains a flexible, rubber-like feel for many, many years. It doesn’t dry or crack, and if properly applied in the first place, it maintains a waterproof seal for a very long time.

The advantage of acrylic caulk is that it is easy to apply, smooth out, and clean up for a very fine finished appearance.

Silicone caulk, however, is notorious for being difficult to neatly apply, smooth out, or clean up. Nonetheless, it is usually the caulk of choice around bathtubs and showers. It is usually also preferred around sinks and toilets, though there is an argument for using the less-messy acrylic caulk anywhere a water leak would be easily discovered before causing any hidden water damage.

Silicone caulk is also preferred for exterior applications where undetected water penetration could cause significant damage. Once applied, if applied properly, it should remain sound for at least a decade.

Be aware that silicone caulk is not paintable. The rubbery surface repels paint as well as water. Either choose a color that matches or coordinates with the surface where it’s being applied, or use a clear caulk that lets the existing surface color show through.

Acrylic Latex Caulk

  • Acrylic latex caulk is a good all-purpose interior caulk. It is mainly used to seal gaps, seams and splits around windows and doors.
  • It can also be used for patching small holes in drywall or plaster walls.
  • Acrylic latex is paintable which makes blends repairs easy.

Silicone Caulk

  • Silicone caulk remains flexible and elastic even after it dries.
  • Silicone caulk can be used virtually anywhere inside the home or out.
  • It is weather resistant and water resistant.
  • Silicone caulk is the trade standard for sealing bathtubs and showers.
  • It bonds very well to almost any surface.
  • Silicone caulk is more expensive than many types of caulk, but is much more versatile.

Specialty Caulks

Adhesive Caulk

With many adhesive caulks, adhesion refers to the caulk’s ability to stick to the surface on which it is applied. Some, however, advertise the power to bond materials together similar to a glue. The former is an excellent property for any caulk, while the latter is perhaps overrated. It’s better to use a serious glue where glue is needed and a good caulk where caulk is needed.

Sanded Caulk for Tile

For tile or granite countertops and backsplashes, a sanded caulk is recommended for the joint where the countertop meets the backsplash. Although joints in tile are usually sealed with a cement-type grout, that type of grout will crack anywhere there is possible movement or flexing, such as between the countertop and wall. The flexible caulk, on the other hand, will not crack.

Sanded caulk is also used on tile floors where the tile meets a wood threshold for the same reason. The potential flexing of the wood as it’s stepped on can crack any cement grout applied adjacent to it.

Sanded caulk can be obtained wherever the cement-type grout is sold and in matching colors. It’s applied with a caulk gun like any normal caulk and is relatively easy to clean up.

Gutter Caulk

When assembling rain gutters, a butyl rubber caulk is often recommended for sealing joints against leaking. This caulk is so messy to work with, it makes using silicone caulk seem like a picnic. Though silicone caulk could be used as an alternative, butyl rubber adheres well to metal and is even more flexible to help maintain a lasting seal as gutters flex under the weight of water.

Butyl rubber is very sticky so have a small, throwaway putty knife and several disposable rags available when you use it. This caulk is not paintable and can only be cleaned up with a solvent. Also, do not apply it on the outside of the rain gutter because it will be a mess. Apply it only on the inside. Because downspout components slip inside one another, there is no concern for leaking and no need for caulk on downspouts.

Butyl Caulking Material

  • Butyl caulking material is available as a tape or in a tube.
  • Works well for sealing larger cracks, gaps and seams. Butyl is generally used for sealing gaps on roofs, around chimneys, flashings and rain gutters.
  • Butyl caulking material can be used indoors or out, but it will never have a finished look.
  • It remains flexible throughout its life and tacky to the touch.

Fire Caulk

For a metal or masonry fireplace hearth, several specialty caulks are available for sealing cracks or gaps to keep heat and flames contained inside the firebox. Variations of fire caulk are also available for sealing openings through fire rated walls, such as between your garage and the living area in your home. Consult the manufacturer’s specifications to select the right caulk for your needs.

Other Caulks

Oil-Based Caulk

  • Oil based caulks will adhere and create a bond with most surfaces. Surfaces require cleaning and grease removal in order to achieve a successful bond.
  • Oil-based caulks are very inexpensive, but are not durable. They caulk, shrink and do not stand up to weather conditions.
  •  Overall, oil-based caulks are not recommended. There are far better products to choose from.

Vinyl Latex Caulk

  • Vinyl latex caulk is a great choice in moisture prone areas such as bathrooms, kitchens, showers, bathtubs and basements.
  • It will bond with most surfaces. Always clean surfaces prior to caulking to remove dirt and oils that can interrupt the bonding process.
  • Vinyl latex caulk can also be used outdoors in areas that temperatures remain moderate year round.

Choose the type of caulk necessary for the job. Just because silicone caulk works under most conditions, does not mean you should use it. Oftentimes, cheaper more affordable caulks can be used in place of silicone.

Caulking Gun

Caulk comes ready for use, generally in a tube. There are various types of caulking compounds available for an assortment of applications. Caulks comes specialized for use on roofs, around windows, furnaces, duct work, outdoor, indoor, heat resistant, flexible; the list goes on and on. Using caulk loaded into a caulking gun is not overly difficult; it does require practice and a steady hand. Once the technique is mastered, you will be caulking like a pro. Using caulk helps to save on heating and cooling costs by creating a barrier that air cannot flow through from the outside or escape from the inside.

Choose a caulking gun from a local hardware store or home improvement center. Caulking guns are all basically the same. There is no need to choose the most expensive.

Loading a Caulking Gun

  1. Slide the caulking gun plunger back as far as it will go. Listen for a click with signifies theplunger locked in place.
  2. Insert the pointy end of the caulking tube through the circle on the end of the caulking gun.
  3. Slide the plunger slowly and carefully down toward the bottom of the tube until the plunger is touching the bottom of the caulking tube.
  4. Cut the pointy tip of the tube off with a utility knife. Slice the point near to the end to avoid caulking flowing from the gun too quickly. Cut the end at a 45-degree angle.


  1.  Hold the caulking gun at a 45-degree angle to the project.
  2.  Begin at the endpoint rather than somewhere in the middle.
  3.  Squeeze the trigger while moving the caulking gun. This will lay down a bead of caulk. It is best to extend your arms and pull the caulk towards you rather than squeezing a bead away from you. Keep your hands as steady as possible and move in a fluid motion, do not stop in the middle, continue to squeeze the trigger and deposit caulk along the length of the project.

Caulking Tips and Tricks

  • Wet your finger and drag it along the caulking bead to smooth and press it in. Wearing a thin rubber gloves will keep hands from getting messy.
  • Drag the back of a plastic spoon across the raised bead to create a flat uniform surface.
  • Drag a wet popsicle stick across the caulk to press it into place.
  • When caulking a bathtub, fill it up with water prior to caulking. Allow the caulk to dry and then drain the bathtub. This technique will keep the caulk from pulling away from the tub edges.
  • Wait for caulking compound to dry completely, shave off jagged edges with a sharp utility knife.
  • Practice laying beads of caulk on a scrap piece of lumber or newspaper until you get the hang of it.
  • Use the appropriate caulk for the project.

Removing Silicone Caulk

Silicone caulk is used to seal edges and cracks in bathrooms and kitchens where water can leak through. Silicone has efficient bonding properties and lasts longer than older types of water based caulk. The problem arises, however, when you try to remove silicone caulk. There are many tools out there that claim to help remove caulk, but one of the best ones is a simple sharp blade.

Tools/Supplies Needed For Caulk Removal

  • Bathroom cleaner
  • Rag
  • Brush
  • Sharp blade
  • Utility or hobby knife
  • Denatured alcohol
  • Shop vac

Don’t let the list above fool you. Removing silicone caulk is just a matter of the “Three C’s”: clean, cut, and clear.


Clean the caulk thoroughly. Use a standard bathroom cleaner, rags and brush. Ensure that any mold or mildew is removed. This sounds simple but it is really one of the most important parts of the job. Cleaning off the caulk will also help to better determine exactly where the caulk line begins and ends and will make your removing job easier.


Insert a new blade into a utility or hobby knife. A good hobby knife in this case might be a better choice, as the knife handle itself is much narrower and easier to maneuver than a utility blade.

Slip the knife in between the edge of the caulk and the wall. Carefully cut down the length of the caulk, trying to avoid any damage to the walls or backsplash. It may be easier to do this in short segments.

Go to the start of the segment you cut in Step 3. Insert the blade on the underside of the caulk, where it meets the countertop or tub edge. Cut down the length of the segment.

Pull the caulk up. Repeat Steps 3-4 as necessary. Continue this process until all the caulk has been removed.

Clear The Residue

Soak a rag in denatured alcohol. Rub this over where you just removed the caulk. Allow it to dry. Vacuum up any bits of remaining caulk with a shop vac.

Helpful Silicone Caulk Removal Tips:

Wear a pair of heavy gloves when cutting away the caulk. This will help protect your hands from slippage. You can line the areas of the backsplash with duct tape or some similar type of heavy tape to help protect them when you are cutting away the caulk.

Silicone caulk is messy. Period. Wear a pair of rubber gloves when you start using the denatured alcohol to clean the caulk away. Once silicone caulk gets on your hands, it doesn’t want to leave.

Caulking a Bathtub-Using Silicone Caulk Like A Pro

Most people look forward to caulking a bathtub with the same enthusiasm as going to the dentist. It’s not much fun but you have to do it anyway.

This simple task has gained a bad reputation because silicone caulk is notorious for being difficult to work with and a mess to clean up. Yet, it’s precisely that rubbery, sticky quality that makes it the number one choice for preventing water leaks around the edges of a tub.

So if you have to do it, here’s how to do it quickly, cleanly, and achieve professional-looking results.

Confidence is Key

Believe it or not, having the confidence that you can do a good job goes a long way toward actually doing a good job. And there’s a logical reason for that.

One of the problems with silicone caulk is that it becomes increasingly difficult to smooth and to clean up as it starts to dry and form a skin. If you haven’t finished the job by the time silicone begins drying, your chances of doing a neat job are going downhill pretty quickly. And if you’re unsure of yourself, you’re going to go slowly, thus assuring your own doom.

On the other hand, with the confidence of knowing the job will look good when you’re done, you proceed with much greater speed and certainty, increasing the odds significantly that your finished job will look great.

It’s that simple. Armed with knowledge of the techniques below, you can gain that confidence necessary to caulk like a pro.

Prepare the Surface

This is the hardest part of the job—removing the old caulk. But you can learn a lot if you pay attention to the caulk you’re removing.

If the previous caulk was applied neatly (but is now old and possibly mildewed), you have an example of how you want your job to look when you’re done. If removing the caulk is a downright chore because it was originally applied sloppily and not smoothed and cleaned up well, then you have an example of what you don’t want your job to look like.

To clean up the old caulk, use a utility knife, putty knife, scouring sponge, and a window scraper (the single edged razor blade in a holder). Start at one corner, loosen enough of the caulk to get a grip on it, and pull out what you can. Tediously scrape and wipe every last remnant of the old caulk from the area, clean it with soap and water and let it dry.

Cut the Tip of the Tube

Here is where many people go wrong, cutting the tip of the caulk tube too large. Applying too much caulk increases the amount of caulk you have to remove and clean up, making the job take longer, and risking it starting to dry before you’re done.

Ideally, you want the width of the caulk bead about equal to the width of the gap you’re trying to fill. Err on the side of cutting the tip too small. If it’s too small you can cut it again. If it’s too large, you’re out of luck.

Apply the Bead Quickly

Here’s another place people go wrong. They go very slowly and carefully, thinking that if they can apply that initial bead perfectly, they won’t have to touch the caulk and there will be no clean up required.

First of all, even the pro knows it will not go perfectly. Second, a rounded bead of caulk, even if perfect, is not as attractive as a smoothed, concave seam. The bottom line is that there is no way you’re going to avoid putting your fingers in it, so you might as well go fast.

Be Fast, But Be Neat

Going fast doesn’t mean you have to be sloppy. Apply the caulk directly into the crack at a steady speed, and don’t worry about having to fill the crack perfectly on the first pass. When you smooth the caulk with your finger, the excess on your finger will fill in some gaps automatically. You can add a little extra caulk to any remaining gaps, and smooth it again.

Using this technique of applying quickly, smoothing quickly, applying again, and smoothing again, you can professionally finish one section of the tub in far less time than you would otherwise.

Clean Up

Even using the professional techniques above, there will still be ridges left behind where the excess oozed out around your fingers while you were smoothing the caulk. You probably encountered this annoying, film-like excess when you removed the old-caulk. Being a very thin coating, it will start to dry fast, so another secret to a great looking job is being ready with a damp linen rag to wipe the film away quickly.

As you’re wiping, avoid pressing the rag into the crack. If you do drag some of your caulk away unintentionally, don’t worry. Apply a little more, and smooth it again.

Final Tips

Until you become experienced, don’t try to do the entire tub at once. Do one wall at a time so you have a better chance of finishing that section before the caulk starts forming a skin. Then move to the next section or wall.

Have a bucket of water and some disposable terry cloth rags at hand. Smoothing caulk is easier when your fingers are damp (not dripping), and you’ll need to clean the caulk from your fingers frequently. With the water and rags at your side, you can clean up quickly as you go. Use the terry rags only for wiping your hands, not for wiping the tub.

Keep in mind; speed is the biggest factor for success. You can apply, smooth, and wipe five times if you have to, as long as you finish before the caulk starts to skin.