The Dos And Don'ts Of Caulking Windows

The Dos and Don’ts of Caulking Windows

Caulking windows to give them a finished look (inside and out) and seal out leaks and drafts is a fairly common DIY task. But if done incorrectly, it can lend a sloppy, amateurish look. Caulk is not a design element; it should blend in with the window and be unnoticeable. “Running a bead,” as the process of caulking is known, requires applying a long, narrow strip along the entire length of the seam and it takes a degree of skill. Keep reading to learn the techniques so you can caulk like a pro.

Whether it’s sealing around the tub, keeping the winter chill at bay, or hiding unsightly cracks in crown moulding; caulking plays an important and often overlooked role in your home. Used to bridge gaps where different building materials meet, caulking performs the essential function of keeping water and outside air where they belong. Hitch Property Constructions has a wide range of caulking services

Proper caulking can prevent mould and rot from forming in your walls and save money on energy bills. In addition, caulking can make your house look better and paint jobs last longer. While today’s high-tech caulk is very durable, it won’t last forever. When it begins to fail, repair the joint as soon as possible to prevent damage to your home.

Types of Caulk

While there are many specialized caulks on the market, the most common ones used by homeowners are:

  • Acrylic Latex: Good for general applications such as sealing around windows, doors, and mouldings. May be used both inside and out as long as the temperature is 40º F or higher while curing. Can be painted and also comes in colours. Water and mildew resistant but needs to dry thoroughly before getting wet. Not as flexible as silicone or butyl rubber, but easier to apply and cleans up with soap and water.
  • Butyl Rubber: Forms a highly water-resistant sealant and is excellent for caulking concrete, brick, or metal surfaces. Can be painted when completely cured. Remains flexible and is a good choice for joints that expand and contract, like gutters and roof flashing. Messy to use and requires solvent for cleanup.
  • Silicone: Best for sealing glass, metal, ceramic tile, and other non-porous surfaces. Doesn’t adhere well to porous materials like wood and masonry. While most brands cannot be painted, it’s available in clear and several colours. Remains flexible after drying. Since nothing sticks to cured silicone—including more silicone—it is hard to repair and leaves a film behind that is difficult to remove. Can be applied at almost any temperature. Emits a sharp odour when curing and requires solvent for cleanup.
  • Kitchen and Bath: Specifically designed for areas subject to high moisture like around sinks and tubs. Comes in a variety of colours that resist mould and mildew growth. Allow drying thoroughly before getting wet. Cleans up with soap and water. Check out our Melbourne caulking services here.

5 Tips for Smoothing Caulk

Caulk is very useful for sealing bathtubs and other fixtures. It can help stop water and moisture from seeping into joints, but it can be a challenge to apply smoothly and achieve a good, even finish. Fortunately, there are a number of simple methods to ensure your silicone caulk looks perfect almost every time.

Masking Tape

The best way to achieve an even bead of silicone caulk is by using masking tape. The tape will keep the caulk from smearing, and it will also give you a straight line to follow as you apply it.

To do this, press a strip of masking tape to the wall above the bathtub and another line to the tub itself. You should allow just enough space between them for a bead of silicone caulk. Also, make sure the tape is straight. When you remove it after smoothing the caulk, you’ll be left with sharp, straight lines even a professional would envy.

Smooth with Your Finger

You can actually smooth caulking down easily with your finger, running it in a long line along with the bead. This can take some practice since you have to keep an even pressure and try to run along the entire length without stopping, if possible. It can take two or three tries to achieve real smoothness.

But there is a trick to it. Before you begin, wet both your finger and a rag with alcohol. Alcohol is both a cutting agent and a lubricant which means your finger will move easily over the silicone. The caulk will need to be cleaned off your finger periodically as you work, so it doesn’t interfere with the smoothing process.


It’s important to start smoothing the bead of silicone caulk before it begins to dry. Once the drying begins, it can be almost impossible to achieve the look you want. You need to approach the caulking confidently and not worry if the bead from the tube is even; when you smooth it out, your fingers will fill in the small gaps.

Use a Damp Rag

You might well find some small ridges left after you’ve run your finger down the silicone caulk. To remove these, use a damp linen rag and run it lightly along with the bead. This will create a very even, professional finish.

Work in Sections

Don’t try and smooth the caulk around a whole tub at once. You’ll achieve much better results if you work in sections. This way, you can proceed quickly and smooth the silicone caulk before it starts to dry and develop a skin. Allow the caulk in one section to dry before you move on to the next. This means taking more time, but the results will be worth it.

Dos and Don’ts of Caulking

DO choose the correct caulk.

You’ll find dozens of types of caulk at your local home improvement store, and each type is intended for a specific situation.

To stand up to the elements, exterior caulk should be impervious to harsh sun rays, water, and fluctuating temperatures. The tube of caulk should specify it’s intended for exterior surfaces; we like Sashco Big Stretch Caulk (available from Amazon).

Interior windows: Caulk used on interior windows should not emit toxic fumes, and it should hold paint well. High quality, paintable latex, such as White Lightning’s Painter’s Preferred Acrylic Latex Caulk (available from Amazon), is a good choice for interior windows.

Humid rooms: Caulking windows in a room with high humidity, such as a bathroom, calls for interior caulk that’s both waterproof and mold-resistant. Kwik Seal Ultra (from The Home Depot) works well in steamy situations.

Masonry siding: When caulking seams between windows and masonry siding, including basement windows and windows on stucco or brick homes, you’ll need an exterior caulk that’s compatible with both the window and the masonry surface. General Electric Max Flex Acrylic Urethane Caulk (available from Amazon) is a solid option for these types of uses.

DON’T caulk over old caulk.

If the existing caulk has hardened and is pulling away, running a bead over it is sure to be an exercise in futility. The old caulk will continue to pull away, taking the new caulk off with it—and before that happens you’ll be faced with a thick, messy caulk line that detracts from the look of the window. Scrape off the old caulk with a steel putty knife, such as HYDE’s 1-1/2″ Flexible Stainless Putty Knife.

DO use a caulking gun with a thumb release.

Cheap caulking guns come with a ratchet-style handle that must be twisted loose to release the pressure on the caulk in the tube. With this type of gun, caulk will keep oozing out until you loosen the handle with your hand, resulting in excess caulk on the window. A better choice is a caulking gun with a thumb release you can press to instantly release the pressure on the caulk so it stops flowing when you’re done running a bead. We like Newborn’s Superior E-Z Thrust Smooth Rod Caulking Gun (available from Amazon) for its convenient thumb release.

DON’T cut too much off the end of the caulk tube tip.

The plastic tip on a caulk tube narrows to a point, and the more you cut off, the larger the bead of caulk will be. Some tubes come with measured cut lines on the tip, allowing you to select the one that most closely matches the width of the seam; others are unmarked. The best practice is to cut off just the end of the tip, and then squeeze out some caulk to see the size of the bead. You can always cut off more, but if you cut off too much at first, your bead will be too thick for the seam.

DO use both hands to run a bead.

It takes two hands to control a caulking gun. Use your dominant hand to hold the gun and pull the trigger, and support the barrel of the gun near the tip with your other hand. Also be sure to keep your wrists straight, moving your elbows and body when running a bead. For example, if caulking a vertical seam, start at the top and as you progress downward, bend your elbows—or knees—to caulk lower while maintaining your wrist position. Bending your wrists would alter the angle of the caulking gun, changing the appearance of the bead.

DON’T run a continuous bead from the top to the bottom or from one side to the other.

By the time you reach the end of the bead, you’ll have to change your grip on the caulk gun, which will affect the uniformity of the bead. Rather, caulk from one end to the middle of the seam and stop. Then, start at the other end and caulk to meet the first bead. This will allow you to maintain a steady hand position, which will result in a uniform bead.

DO ride the smooth edge when caulking a seam between a window and textured siding.

Siding is often textured, and if you slide the tip of the tube along the bumpy texture, the bead of caulk will also be bumpy. The solution is to allow the tip of the tube to slide, or “ride” as the pros say, only along the smooth window edge. Keep the tip from riding the textured siding as you’re running the bead. The caulk will still seal the seam, and you’ll have a better-looking bead. Check out Hitch Property Constructions for a huge range of Melbourne caulking services

DON’T smooth the bead of caulk all the way from one end to the other.

After running the bead, you’ll want to smooth it, either with a wet finger or caulk applicator, such HYDE’s Caulk-Rite Pro Application Tool (available from Amazon). The best way to smooth the bead is to start about six inches from the bottom and smooth that small section first. Then, move up another six inches and smooth that section next, pulling downward toward the section you just smoothed. Amateurs often try to smooth the entire bead at one time, which causes excess caulk to build up and overflow on the sides of the seam. Smoothing just a small section at a time will give you a professional look and prevent a mess of excess caulk on the sides of the seam. It takes caulk a couple of hours to start drying, so you should have ample time to smooth in this manner.

DO tape off your seams if you can’t run a smooth bead.

If your hands are shaky or you just can’t seem to move the caulking gun smoothly enough to run a uniform bead, you can still obtain good results by taping off the seam with painter’s tape. Simply attach strips of painter’s tape along both edges of the seam, approximately 1/8″ away from the seam itself. Then, run the bead of caulk and smooth it off as described above. As soon as you’ve smooth the bead, carefully pull off the painter’s tape, and you’ll have a perfect 1/4″ caulk line.

DON’T use caulk as a filler for poorly trimmed-out windows.

Caulk is intended for use on relatively narrow seams, typically 1/4″ wide or tighter. If applied to large gaps, caulk can sag out of the gap and create an unattractive mess. If you have gaps wider than 1/4″, the best practice is to fill them first with a foam backer rod, such as this C.R. Laurence Closed Cell Backer Rod (available from Amazon) and then run your bead of caulk.

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